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  • 1
    Electronic Resource
    Electronic Resource
    A novel method for immobilization of invertase from the thermophilic fungus, Thermomyces lanuginosus (2000)
    Springer
    World journal of microbiology and biotechnology 16 (2000), S. 151-154 
    Details
    ISSN: 1573-0972
    Keywords: Invertases ; immobilization ; phenyl-Sepharose ; thermophilic fungus ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An invertase from the thermophilic fungus, Thermomyces lanuginosus was immobilized on phenyl-Sepharose and its properties were studied. Between the soluble and immobilized forms of the invertase, there were not much difference in their optimum pH, K M and V max for sucrose. In contrast, the K M and V max for raffinose changed significantly. The optimum temperature for the immobilized invertase was lower by 10 ∘C. The immobilized invertase showed remarkable stability at 50 ∘C and was less sensitive to inhibition by metal ions. There was no leaching of the enzyme for at least a month when stored in the refrigerator. The method is novel and specific for the thermophilic invertase as a mesophilic invertase (from yeast) did not bind to phenyl-Sepharose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008901801373
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of various carbon and nitrogen sources on cellulose synthesis by Acetobacter xylinum (2000)
    Springer
    World journal of microbiology and biotechnology 16 (2000), S. 245-248 
    Details
    ISSN: 1573-0972
    Keywords: Acetobacter xylinum ; biotechnology ; carbon source ; cellulose membrane ; immobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of various carbon and nitrogen sources on cellulose membrane production by Acetobacter xylinum was evaluated. Among the carbon sources, sucrose, glucose and mannitol were found to be suitable for optimum levels of cellulose production. The strain was able to utilize a wide range of protein and nitrogen sources such as peptone, soybean meal, glycine, casein hydrolysate, and glutamic acid for cellulose synthesis. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of pellicle proteins (PP) revealed electrophoretic bands of molecular masses in the range of 116–20 kDa. Furthermore, the strain can be useful for the removal of various nitrogenous and carbon substrates present in waste waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008958014270
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous filtration and immobilization of cells from a flowing suspension using a bioreactor containing polyethylenimine coated cotton threads: Application in the continuous inversion of concentrated sucrose syrups (1999)
    Springer
    World journal of microbiology and biotechnology 15 (1999), S. 17-21 
    Details
    ISSN: 1573-0972
    Keywords: Adhesion ; cotton threads ; immobilization ; invert sugar ; microbial filter ; polyethylenimine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Polyethylenimine(PEI)-coated cotton threads were shown to have potential for reducing microbial load from a flowing suspension. Turbid cell suspensions perfused through the PEI column appeared as totally clear in the effluent. The adhesion efficiency of the matrix was found to depend on the concentration of PEI used to treat the threads. Threads coated with 2.5% PEI were found to show optimal retention of cells. A considerable amount of binding was seen over a broad range of ionic concentration (0–0.3 M) and pH (3.6–10.3). Under similar conditions control threads did not show any filtration capacity. Saccharomyces cerevisiae, Saccharomyces fragilis, Escherichia coli and an Acetobacter species could be effectively filtered using PEI-coated threads. This technique can find potential for the simultaneous filtration and immobilization of cells in a bioreactor to be used in continuous bioprocessing as exemplified for the inversion of sucrose syrups using baker's yeast. The bioreactor could continuously hydrolyse 60% (w/v) sucrose syrups with a productivity of 2.25 kg/day for over a month without loss in efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008877126664
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  • 4
    Electronic Resource
    Electronic Resource
    Performance and efficiency of a yeast biofilter for the treatment of a Nigerian fertilizer plant effluent (1999)
    Springer
    World journal of microbiology and biotechnology 15 (1999), S. 515-516 
    Details
    ISSN: 1573-0972
    Keywords: Biofilter ; biodegradation ; effluent ; fertilizer ; immobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A biofilter composed of yeasts and cassava peel was used to detoxify fertilizer plant effluent. The biological oxygen demand was reduced on treatment from a range of 1200–1400 mg/l to a range 135–404 mg/l. The ammonia-nitrogen (NH3–N) and nitrate-nitrogen (NO3–N) were reduced after treatment from 1000 to 10 mg/l and from 100 to 17.6 mg/l, respectively. The biofilter is simple and easy to handle with high efficiency of 98%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008931824416
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  • 5
    Electronic Resource
    Electronic Resource
    Biotransformation of codeine to morphine in freely suspended cells and immobilized cultures of Spirulina platensis (1999)
    Springer
    World journal of microbiology and biotechnology 15 (1999), S. 465-469 
    Details
    ISSN: 1573-0972
    Keywords: Biotransformation ; codeine ; immobilization ; morphine ; Spirulina platensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Both freely suspended cells and immobilized cultures of Spirulina platensis, a blue-green alga, biotransformed exogenously fed codeine, an opium alkaloid, to morphine. The external addition of codeine to the culture medium did not affect the growth of S. platensis. Immobilization of Spirulina in a calcium alginate gel matrix was optimized by using 2% (w/v) sodium alginate and reducing the concentration of nutrients of Zarrouk's medium, which caused destabilization of the calcium alginate gel. The accumulation of morphine increased gradually and reached maxima of 330 μg 100 ml−1 culture at 105 h in freely suspended and 351 μg 100 ml−1 at 96 h in immobilized Spirulina cultures. Accumulation of morphine was detected only in the medium, whereas cells did not show accumulation. The immobilized Spirulina cultures showed marginally higher conversion of codeine to morphine over freely suspended cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008975901642
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  • 6
    Electronic Resource
    Electronic Resource
    Short Communication: Immobilization of urease from pigeonpea (Cajanus cajan L.) on flannel cloth using polyethyleneimine (1998)
    Springer
    World journal of microbiology and biotechnology 14 (1998), S. 927-929 
    Details
    ISSN: 1573-0972
    Keywords: Urease ; pigeonpea ; Cajanus cajan ; immobilization ; urea analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Urease of pigeonpea has been immobilized on polyethyleneimine-activated cotton cloth followed by cross-linking with dimethyl suberimidate. Optimum immobilization (56%) was obtained at a protein loading of 1.2mg/5×5cm2 cloth piece. The immobilized enzyme stored in 0.1M Tris/acetate buffer, pH6.5, at 4°C had a t1/2 of 70 days. There was practically no leaching of the enzyme from the immobilization matrix in 15 days. The immobilized enzyme was used 7 times at an interval of 24h between each use with 75% residual activity at the end of the period. Blood urea analysis was carried out with immobilized urease for some clinical samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008897600256
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  • 7
    Electronic Resource
    Electronic Resource
    Removal of gaseous n-valeric acid in the air by Rhodococcus sp. B261 immobilized onto ceramic beads (1998)
    Springer
    World journal of microbiology and biotechnology 14 (1998), S. 343-348 
    Details
    ISSN: 1573-0972
    Keywords: Biofilter ; immobilization ; malodour ; volatile fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract n-Valeric acid, one of the main malodorous pollutants from livestock houses was eliminated with a biofilter prepared with Rhodococcus sp. B261 immobilized onto ceramic beads. The strain was isolated from composted pig faeces and grown in an artificial medium containing volatile fatty acids as a carbon source. The cells were immobilized onto ceramic beads in vacuo. The beads were aseptically incubated at 37 °C, pH 8.0, for 24h for activation of the cells. The beads with immobilized cells (3.36×109 c.f.u./g ceramic beads) and moisture content of 35% (w/w) were packed into a glass column equipped with a water jacket to keep the temperature constant. One hundred-seventy ppm of gaseous n-valeric acid were removed for 11 days at 30h -1 (space velocity) and 37 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008805009604
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of surfactants on the production of ergot-alkaloids by immobilized mycelia of Claviceps paspali (1998)
    Springer
    World journal of microbiology and biotechnology 14 (1998), S. 447-450 
    Details
    ISSN: 1573-0972
    Keywords: Claviceps ; ergot alkaloids ; immobilization ; surfactant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In a semicontinuous process immobilized Claviceps paspali mycelia produced alkaloids over a period of 60 days (six reincubations). By addition of the surfactant Pluronik, a polyethoxypolypropoxy polymer, a considerable increase in alkaloid biosynthesis occurred. The maximum product concentration achieved was 8.35gl-1, and the overall productivity was 5.80 mgl-1 h-1, which is half the productivity of the batch process. Maximum process productivity for a single reincubation (12.3 mg l-1 h-1) was almost equal to the batch process productivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008837916873
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  • 9
    Electronic Resource
    Electronic Resource
    Immobilization of manganese peroxidase from Lentinula edodes and its biocatalytic generation of MnIII-chelate as a chemical oxidant of chlorophenols (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 204-215 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; white-rot fungi ; Lentinula edodes ; manganese peroxidase ; Mn3+ ; azlactone ; chlorophenol ; EEDQ ; biocatalyst ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Manganese peroxidase (MnP) purified from commercial cultures of Lentinula edodes was covalently immobilized through its carboxyl groups using an azlactone-functional copolymer derivatized with ethylenediamine and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) as a coupling reagent. The tethered enzyme was employed in a two-stage immobilized MnP bioreactor for catalytic generation of chelated MnIII and subsequent oxidation of chlorophenols. Manganese peroxidase immobilized in the enzyme reactor (reactor 1) produced MnIII-chelate, which was pumped into another chemical reaction vessel (reactor 2) containing the organopollutant. Reactor 1-generated MnIII-chelates oxidized 2,4-dichlorophenol and 2,4,6-trichlorophenol in reactor 2, demonstrating a two-stage enzyme and chemical system. H2O2 and oxalate chelator concentrations were varied to optimize the immobilized MnP's oxidation of MnII to MnIII. Oxidation of 1.0 mM MnII to MnIII was initially measured at 78% efficiency under optimized conditions. After 24 h of continuous operation under optimized reaction conditions, the reactor still oxidized 1.0 mM MnII to MnIII with ∼69% efficiency, corresponding to 88% of the initial MnP activity. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 204-215, 1998.
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  • 10
    Electronic Resource
    Electronic Resource
    Adsorption and enzyme (β-galactosidase and α-chymotrypsin): Immobilization properties of gel fiber prepared by the gel formation of cellulose acetate and titanium iso-propoxide (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 651-656 
    Details
    ISSN: 0006-3592
    Keywords: cellulose ; gel ; fiber ; immobilization ; adsorption ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We prepared a new composite gel fiber by the gel formation of cellulose acetate and titanium iso-propoxide. The fiber is harder than alginate gel; it is also stable in common solvents, phosphate solution, and electrolyte solutions over a wide range of pH from 3 to 10. The fiber shows amphoretic adsorption properties depending on pH, namely, it acts anionic with decreasing pH and cationic with increasing pH. However, the fiber had no adsorption property for a pyrogen endotoxin. The β-galactosidase and α-chymotrypsin not retained in alginate gel were immobilized on the fibers by this method. The pH, temperature, and repeated run stabilities of the immobilized enzyme were compared to those of the native one. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:651-656, 1998.
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  • 11
    Electronic Resource
    Electronic Resource
    Growth Stimulation of Tumor-Specific Cytotoxic T Lymphocytes on Concanavalin A-Immobilized Carrier Beads (1998)
    Springer
    Cytotechnology 26 (1998), S. 13-21 
    Details
    ISSN: 1573-0778
    Keywords: concanavalin A ; cytotoxic T lymphocytes ; immobilization ; interleukin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Human tumor-specific CD4+ cytotoxic T lymphocytes (CTL) were generated against duodenum papilloma cell line TGBC18TKB from HLA type-matched peripheral blood mononuclear cells. Concanavalin A (Con A) immobilized on carrier beads stimulated growth of the CTL in a long-term culture without repeated antigen stimulation, while soluble Con A induced death of the CTL. The CTL exhibited the target-specific cytotoxicity in a more potent manner than those before the long-term culture in the presence of the immobilized Con A. Enhanced expression of the adhesion molecule, CD11b, was observed on the CTL. These results suggest that immobilized Con A will be useful for continuous growth stimulation and large scale expansion of CTL without tumor antigen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007924430570
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  • 12
    Electronic Resource
    Electronic Resource
    Maintenance of steroid 11-hydroxylation activity in immobilized Cunninghamella elegans protoplasts (1997)
    Springer
    World journal of microbiology and biotechnology 13 (1997), S. 469-473 
    Details
    ISSN: 1573-0972
    Keywords: 2-Deoxy-d-glucose ; hydroxylation ; immobilization ; polyoxin ; protoplasts ; steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018540620234
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  • 13
    Electronic Resource
    Electronic Resource
    Bioreduction of a carbon–nitrogen double bond using immobilized baker's yeast’a first report (1997)
    Springer
    World journal of microbiology and biotechnology 14 (1997), S. 247-250 
    Details
    ISSN: 1573-0972
    Keywords: Baker's yeast ; 18-crown-6 ; imines ; immobilization ; oximes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Immobilized baker's yeast entrapped in calcium alginate beads efficiently reduces N-benzylidinemethylamine to N-methylbenzylamine in hexane at 37°C and tetrahydrofuran (THF) at 30°C in the presence of 18-crown-6, while in the presence of water as cosolvent and glucose as an additive N-benzylidinemethylamine undergoes decomposition. Benzaldoxime in a hexane–water (1:9) solvent system containing glucose as an additive is reduced to N-benzylhydroxylamine. On using an ethanol–water (1:1) solvent system, benzaldoxime is converted to benzyl alcohol and in hexane, benzene, THF, hexane–water (1:1) or acetonitrile–water (1:1) solvent systems, or using dried baker's yeast in different solvent systems, transformation of benzaldoxime does not occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008894416058
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  • 14
    Electronic Resource
    Electronic Resource
    Production, purification and immobilization of glucose isomerase from Streptomyces olivochromogenes PTCC 1547 (1997)
    Springer
    World journal of microbiology and biotechnology 13 (1997), S. 597-598 
    Details
    ISSN: 1573-0972
    Keywords: Glucose isomerase ; immobilization ; production ; purification ; Streptomyces olivochromogenes PTCC 1457
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Production of glucose isomerase from Streptomyces olivochromogenes PTCC 1457 was followed by its purification and immobilization. Different immobilization methods including the use of a hydrophobic support were investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018590031137
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  • 15
    Electronic Resource
    Electronic Resource
    Biodegradation of olive oil mill wastewaterby Coriolus versicolor and Funalia trogii:effects of agitation, initial COD concentration, inoculum size and immobilization (1997)
    Springer
    World journal of microbiology and biotechnology 14 (1997), S. 37-42 
    Details
    ISSN: 1573-0972
    Keywords: Biodegradation ; immobilization ; laccase ; olive oil mill wastewater ; white rot fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The biodegradation of olive oil mill wastewater (OOMW) by Coriolus versicolor and Funalia trogii was investigated. Initial COD concentration, agitation and inoculum size were all found to be significant for biodegradation. Adding glucose, sulphate or nitrogen had no effect on biodegradation. During growth in optimum conditions, C.versicolor removed approximately 63% COD, 90% phenol and 65% colour within 6 days and F. trogii removed approximately 70% COD, 93% phenol and 81% colour of the OOMW used. The fungi also excreted large amounts of extracellular laccase into the medium. High biodegradation yields were also obtained by fungi immobilized in calcium alginate gels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008816231563
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  • 16
    Electronic Resource
    Electronic Resource
    The use of monochloroacetic acid for improved ethanol production by immobilized Saccharomyces cerevisiae (1997)
    Springer
    World journal of microbiology and biotechnology 14 (1997), S. 107-111 
    Details
    ISSN: 1573-0972
    Keywords: Glutaraldehyde ; immobilization ; monochloroacetic acid ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008888820176
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  • 17
    Electronic Resource
    Electronic Resource
    Taxol (paclitaxel) production using free and immobilized cells of Taxus cuspidata (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 214-219 
    Details
    ISSN: 0006-3592
    Keywords: Taxol ; plant cell culture ; continuous production ; immobilization ; Taxus cuspidata ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production characteristics for Taxol (paclitaxel) using free and immobilized cells of Taxus cuspidata were investigated in a perfusion culture bioreactor. Although the cell growth was inhibited by higher dilution rates, the specific production rate of Taxol was increased by perfusion compared with that using batch operation. Perfusion cultures using a nylon-mesh cell separator for free suspension cells showed similar production profiles to those obtained using immobilized cells. Continuous Taxol production was successfully obtained at an approximate specific production rate of 0.3 mg/g DCW (dry cell weight) per day for up to 40 days. © 1997 John Wiley & Sons, Inc.
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  • 18
    Electronic Resource
    Electronic Resource
    Trehalase immobilization on aminopropyl glass for analytical use (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 33-39 
    Details
    ISSN: 0006-3592
    Keywords: trehalase ; trehalose ; immobilization ; aminopropyl glass ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Trehalase is the enzyme which hydrolyzes the disaccharide trehalose into two α-D-glucose molecules. In this article, we present the immobilization of trehalase on aminopropyl glass particles. The enzyme was extracted from Escherichia coli Mph2, a strain harboring the pTRE11 plasmid, which contains the trehalase gene. The partially purified enzyme had a specific activity of 356 U/mg and could be used for quantifying trehalose in the presence of sucrose, maltose, lactose, starch, and glycogen. Partially purified trehalase was immobilized by covalent coupling with retention of its catalytic activity. The support chosen for the majority of the experiments reported was aminopropyl glass, although spherisorb-5NH2 and chitin were also tested. The immobilized enzyme was assayed continuously for 40 h, at pH 6.0 and 30°C, and no release of enzyme molecules was detected during this procedure. The best condition found for storing the enzyme-support complex was at 4°C in the presence of 25 mM sodium maleate, containing 7 mM β-mercaptoethanol, 1 mM ethylenediaminetetraacetic acid (EDTA), and 50% glycerol. The enzyme under these conditions was stable, retaining approximately 100% of its initial activity for at least 28 days. The immobilized enzyme can be employed to detect trehalose molecules in micromolar concentration. The optimum pH value found was 4.5 and the Km app. 4.9 × 10-3 M trehalose at pH 4.6 and 30°C, with Vmax of 5.88 μmol glucose · min.-1, as calculated by a Lineweaver-Burk plot. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 33-39, 1997.
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  • 19
    Electronic Resource
    Electronic Resource
    Dramatically stabilized phosphotriesterase - polymers for nerve agent degradation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 105-114 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; phosphotriesterase ; immobilization ; polyurethane foam ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phosphotriesterase (EC 3.1.8.1) was immobilized within a polyurethane foam matrix during polymer synthesis using a prepolymer synthesis strategy. In addition to retaining greater than 50% of the enzyme specific activity, numerous benefits were incurred upon immobilization. Orders of magnitude increases in storage and thermal stability (net stabilization energy = 12.5 kJ/mol) were observed without the need for enzyme premodification. The immobilized enzyme system was protease resistant and seemed to display no adverse effects from immobilization, such as an alteration of enzyme function. The organic solvent, dimethyl sulfoxide, also exhibited a stabilizing effect on phosphotriesterase enzyme systems over a range of intermediate concentrations. We attribute these effects in part to direct interaction between the aprotic solvent and metal containing residues present at the enzyme's active site. Our data demonstrate that just 2.5 kg of immobilized enzyme may be sufficient to degrade 30,000 tons of nerve agent in just 1 year. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 105-114, 1997.
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  • 20
    Electronic Resource
    Electronic Resource
    Protein production using recombinant yeast in an immobilized-cell-film airlift bioreactor (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 241-251 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; plasmid stability ; recombinant yeast ; glucoamylase, bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A recombinant Saccharomyces cerevisiae C468/pGAC9 (ATCC 20690), which expresses Aspergillus awamori glucoamylase gene under the control of the yeast enolase I (ENO1) promoter and secretes glucoamylase into the extracellular medium, was used as a model system to investigate the effect of cell immobilization on bioreactor culture performance. Free suspension cultures in stirred-tank and airlift bioreactors confirmed inherent genetic instability of the recombinant yeast. An immobilized-cell-film airlift bioreactor was developed by employing cotton cloth sheets to immobilize the yeast cells by attachment. Enhanced enzyme productivity and production stability in the immobilized-cell system were observed. Experimental data indicated that the immobilized cells maintained a higher proportion of plasmid-bearing cells for longer periods under continuous operation. The higher plasmid maintenance with immobilized cells is possibly due to reduced specific growth rate and increased plasmid copy number. Double-selection pressure was used to select and maintain the recombinant yeast. The selected strain showed better production performance than the original strain. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 241-251, 1997.
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  • 21
    Electronic Resource
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    Thermophilic sulphate and sulphite reduction in lab-scale gas-lift reactors using H2 and CO2 as energy and carbon source (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 807-814 
    Details
    ISSN: 0006-3592
    Keywords: sulphate reduction ; sulphite reduction ; biofilm ; immobilization ; gas-lift reactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Feasibility of thermophilic (55°C) sulphate and sulphite reduction with H2 and CO2 gas-mixtures was studied in gas-lift reactors, which contained pumice particles as carrier material. Particular attention was paid to biomass retention and the competition between hydrogenotrophic sulphate-reducers and other hydrogenotrophic thermophiles. A model medium with defined mineral nutrients was used.The results of the experiments clearly demonstrate that sulphate conversion rates up to 7.5 g SO42-/L per day can be achieved. With sulphite, a reduction rate of 3.7 g S/L per day was obtained, which equals a sulphate conversion rate of 11.1 g SO42-/L per day. Under the applied conditions, a strong competition for hydrogen between hydrogenotrophic sulphate-reducers, tentatively designated as Desulfotomaculum sp., and hydrogenotrophic methanogens was observed. The outcome of the competition could not be predicted. Growth of the mixed culture was totally inhibited at an H2S concentration of 250 mg/L. Poor attachment of sulphate-reducing bacteria was observed in all experiments. The biomass concentration did not exceed 1.2 g/L, despite the presence of 50 g/L of pumice. The reason for this phenomenon remains to be understood. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 807-814, 1997.
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  • 22
    Electronic Resource
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    Performance of a sulfide-oxidizing expanded-bed reactor supplied with dissolved oxygen (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 32-40 
    Details
    ISSN: 0006-3592
    Keywords: expanded-bed reactor ; sulfur ; Thiobacilli ; immobilization ; biofilm ; sludge ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The performance of a new sulfide-oxidizing, expanded-bed bioreactor is described. To stimulate the formation of well-settleable sulfur sludge, which comprises active sulfide-oxidizing bacterial biomass and elemental sulfur, the aeration of the liquid phase and the oxidation of sulfide to elemental sulfur are spatially separated. The liquid phase is aerated in a vessel and subsequently recirculated to the sulfide-oxidizing bioreactor. In this manner, turbulencies due to aeration of the liquid phase in the bioreactor are avoided. It appeared that, under autotrophic conditions, almost all biomass present in the reactor will be immobilized within the sulfur sludge which consists mainly of elemental sulfur (92%) and biomass (2.5%). The particles formed have a diameter of up to 3 mm and can easily be grinded down. Within time, the sulfur sludge obtained excellent settling properties; e.g., after 50 days of operation, 90% of the sludge settles down at a velocity above 25 m h-1 while 10% of the sludge had a sedimentation velocity higher than 108 m h-1. Because the biomass is retained in the reactor, higher sulfide loading rates may be applied than to a conventional “free-cell” suspension. The maximum sulfide-loading rate reached was 14 g HS- L-1 d-1, whereas for a free-cell suspension a maximum loading rate of 6 g HS- L-1 d-1 was found. At higher loading rates, the upward velocities of the aerated suspension became too high so that sulfur sludge accumulated in the settling zone on top of the reactor. When the influent was supplemented with volatile fatty acids, heterotrophic sulfur and sulfate reducing bacteria, and possibly also (facultatively) heterotrophic Thiobacilli, accumulated within the sludge. This led to a serious deterioration of the system; i.e., the sulfur formed was increasingly reduced to sulfide, and also the formation rate of sulfur sludge declined. © 1997 John Wiley & Sons, Inc.
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    Properties of free and immobilized lipase from Pseudomonas cepacia (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 56 (1997), S. 181-189 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; immobilization ; polypropylene support ; Pseudomonas cepacia ; kinetic parameters ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The purified lipase from Pseudomonas cepacia (PS, Amano) was immobilized on a commercially available microporous polypropylene support. The enzyme was rapidly and completely adsorbed on the support. Special attention was devoted to the demonstration of the lack of diffusional limitations, either internal or external, when a soluble substrate (p-nitrophenylacetate, pNPA) was used. The activity yield was high (100%) with pNPA and very low (0.4%) with p-nitrophenylpalmitate (pNPP). These values clearly showed that the immobilized enzyme was fully active as soon as activity was assayed on a soluble substrate rather than an insoluble one. With the latter one, the low activity was due mainly to a slow rate of substrate diffusion inside the porous support. The same diffusional phenomenon could explain the complete change of fatty acid specificity of the immobilized lipase. After immobilization, the lipase was mainly specific for short chain fatty acid esters, whereas the free enzyme was mainly specific for long chain esters. The activity-versus-temperature profiles were not greatly affected by immobilization with maximal reaction rates in the range 45° to 50°C for both enzyme preparations. However, immobilization increased enzyme stability mainly by decreasing the sensitivity to temperature of the inactivation reaction. Half-lives at 80°C were 11 and 4 min for the immobilized and free enzymes, respectively. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 181-189, 1997.
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    Dialysis cultures with immobilized hybridoma cells for effective production of monoclonal antibodies (1997)
    Springer
    Cytotechnology 23 (1997), S. 39-45 
    Details
    ISSN: 1573-0778
    Keywords: fixed bed reactor ; immobilization ; dialysis technique ; hybridoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An industrial scale reactor concept for continuous cultivation of immobilized animal cells (e.g. hybridoma cells) in a radial-flow fixed bed is presented, where low molecular weight metabolites are removed via dialysis membrane and high molecular products (e.g. monoclonal antibodies) are enriched. In a new “nutrient-split” feeding strategy concentrated medium is fed directly to the fixed bed unit, whereas a buffer solution is used as dialysis fluid. This feeding strategy was investigated in a laboratory scale reactor with hybridoma cells for production of monoclonal antibodies. A steady state monoclonal antibody concentration of 478 mg l-1 was reached, appr. 15 times more compared to the concentration reached in chemostat cultures with suspended cells. Glucose and glutamine were used up to 98%. The experiments were described successfully with a kinetic model for immobilized growing cells. Conclusions were drawn for scale-up and design of the large scale system. Abbreviations: cGlc – glucose concentration, mmol l-1; cGln – glutamine concentration, mmol l-1; cAmm – ammonia concentration, mmol l-1; cLac – lactate concentration, mmol l-1; cMAb – MAb concentration, mg l-1; D – dilution rate, d-1; Di – dilution rate in the inner chamber of the membrane dialysis reactor, d-1; D0 – dilution rate in the outer chamber of the membrane dialysis reactor, d-1; q*FB,Glc – volume specific glucose uptake rate related to the fixed bed volume, mmol lFB -1 h-1; q*FB,Gln – volume specific glutamine uptake rate related to the fixed bed volume, mmol lFB -1 h-1.
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    Changes in monoclonal antibody productivity of recombinant BHK cells immobilized in collagen gel particles (1997)
    Springer
    Cytotechnology 23 (1997), S. 5-12 
    Details
    ISSN: 1573-0778
    Keywords: monoclonal antibody ; immobilization ; collagen gel ; BHK ; productivity ; recombinant ; high density culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Animal cell perfusion high density culture is often adopted for the production of biologicals in industry. In high density culture sometimes the productivity of biologicals has been found to be enhanced. Especially in immobilized animal cell culture, significant increase in the productivity has been reported. We have found that the specific monoclonal antibody (MAb) productivity of an immobilized hybridoma cell is enhanced more than double. Several examples of enhancing productivities have been also shown by collagen immobilized cells. Immobilized cells involve some different points from non-immobilized cells in high density culture: In immobilized culture, some cells are contacted together, resulting in locally much higher cell concentration more than 108 cells/ml. Information originating from a cell can be easily transduced to the others in immobilized culture because the distance between cells is much nearer. Here we have performed collagen gel immobilized culture of recombinant BHK cells which produce a human IgG monoclonal antibody in a protein-free medium for more than three months. In this high density culture a stabilized monoclonal antibody production was found with around 8 times higher specific monoclonal antibody productivity compared with that in a batch serum containing culture. No higher MAb productivity was observed using a conditioned medium which was obtained from the high density culture, indicating that no components secreted from the immobilized cells work for enhancing monoclonal antibody production. The MAb productivity by the non-immobilized cells obtained by dissolving collagen using a collagenase gradually decreased and returned to the original level in the batch culture using a fresh medium. This suggests that the direct contact of the cells or a very close distance between the cells has something to do with the enhancement of the MAb productivity, and the higher productivity is kept for a while in each cell after they are drawn apart.
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    Short communication: Ethanol production from cellulose at 45°C using a batch-fed system containing alginate-immobilized Kluyveromyces marxianus IMB3 (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 103-104 
    Details
    ISSN: 1573-0972
    Keywords: Alginate ; cellulase ; cellulose ; ethanol ; immobilization ; Kluyveromyces marxianus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The thermotolerant yeast, Kluyveromyces marxianus IMB3, was grown in batch culture at 45°C on cellulose-containing media, supplemented with exogenous cellulase activity. At various stages during fermentation, both substrate and enzyme were added in batch mode and fermentation was continued for 220 h. Ethanol production increased to 20 g/l at 200 h, representing 45% of the maximum theoretical yield. In subsequent experiments, the organism was immobilized in calcium alginate beads and these were used in a similar, batch-fed system at 45°C. Again, fermentation was continued for 220 h and ethanol production increased to its maximum, of 28 g/l, within 100 h and this represented in excess of 60% of the maximum theoretical yield.
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    Cell-recycle batch fermentation using immobilized cells of flocculent Saccharomyces cerevisiae wine strains (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 25-27 
    Details
    ISSN: 1573-0972
    Keywords: Batch fermentation ; immobilization ; Saccharomyces cerevisiae ; secondary products ; wine yeast ; wine making
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Five, highly flocculeng strains of Saccharomyces cerevisiae, isolated from wine, were immobilized in calcium alginate beads to optimize primary must fermentation. Three cell-recycle batch fermentations (CRBF) of grape musts were performed with the biocatalyst and the results compared with those obtained with free cells. During the CRBF process, the entrapped strains showed some variability in the formation of secondary products of fermentation, particularly acetic acid and acetaldehyde. Recycling beads of immobilized flocculent cells is a good approach in the development and application of the CRBF system in the wine industry.
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    Comparison of citric acid production byAspergillus niger immobilized in gels and cryogels of polyacrylamide (1996)
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 351-353 
    Details
    ISSN: 1476-5535
    Keywords: citric acid ; Aspergillus niger ; immobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Aspergillus niger was immobilized in cryogels and in conventional gels of polyacrylamide. The growth of cells entrapped in two kinds of gels and the production of citric acid by the immobilized cells were investigated and compared. Cells immobilized in cryogels were more suitable for citric acid production.
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    Glucose oxidase and catalase activities ofPenicillium variabile P16 immobilized in polyurethane sponge (1996)
    Springer
    Journal of industrial microbiology and biotechnology 17 (1996), S. 15-19 
    Details
    ISSN: 1476-5535
    Keywords: glucose oxidase ; catalase ; Penicillium variabile ; immobilization ; polyurethane sponge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Conidia ofPenicillium variabile P16 were immobilized in polyurethane sponge and used in repeated-batch processes in a fluidized-bed reactor. Optimal conditions for production of glucose oxidase and catalase were: inoculum size, 10%; glucose concentration, 80 g L−1; Ca-carbonate concentration, 15 g L−1; temperature, 28°C and aeration rate, 4 VV−1 min−1. In an extended repeated-batch process, glucose oxidase activity was highest after the fourth batch and catalase activity was highest after the fifth batch. Scanning electron microscopy showed that the fungus grew only in the interior of carrier particles.
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    Ethanol production by immobilized whole cells ofZymomonas mobilis in a continuous flow expanded bed bioreactor and a continuous flow stirred tank bioreactor (1996)
    Springer
    Journal of industrial microbiology and biotechnology 17 (1996), S. 11-14 
    Details
    ISSN: 1476-5535
    Keywords: continuous flow reactor ; ethanol ; expanded bed reactor ; immobilization ; Zymomonas mobilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Continuous ethanol fermentation by immobilized whole cells ofZymomonas mobilis was investigated in an expanded bed bioreactor and in a continuous stirred tank reactor at glucose concentrations of 100, 150 and 200 g L−1. The effect of different dilution rates on ethanol production by immobilized whole cells ofZymomonas mobilis was studied in both reactors. The maximum ethanol productivity attained was 21 g L−1 h−1 at a dilution rate of 0.36 h−1 with 150 g glucose L−1 in the continuous expanded bed bioreactor. The conversion of glucose to ethanol was independent of the glucose concentration in both reactors.
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    Environmental applications of immobilized microbial cells: A review (1996)
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 79-101 
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    ISSN: 1476-5535
    Keywords: alginate ; bacteria ; biodegradation ; bioremediation ; κ-carrageenan ; encapsulation ; immobilization ; microorganisms ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Immobilized microbial cells have been used extensively in various industrial and scientific endeavours. However, immobilized cells have not been used widely for environmental applications. This review examines many of the scientific and technical aspects involved in using immobilized microbial cells in environmental applications, with a particular focus on cells encapsulated in biopolymer gels. Some advantages and limitations of using immobilized cells in bioreactor studies are also discussed.
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    A new continuous biofilm bioreactor for immobilized oil-degrading filamentous fungi (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 20-25 
    Details
    ISSN: 0006-3592
    Keywords: filamentous fungi ; immobilization ; biofilm bioreactor ; oil emulsion ; degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new type of horizontal biofilm bioreactor for continuous bioconversion of emulsified oily substrate by immobilized growing biofilm of filamentous fungi was designed, constructed, and feasibility tested. The new reactor design provides “self”-immobilization of homogenized mycelium leading to even biofilm development. This was accomplished by using stainless steel screens of optimal mesh, mounted in parallel and stretching outward from a main rotating axis of a biological rotating contractor. Each screen was equipped with a pair of stainless steel blades mounted on supports allowing for continuous biofilm “shaving” beyond a predetermined thickness, thus retaining freshly growing active biofilm surface. The feasibility of the new bioreactor was demonstrated by decalactone production from emulsified castor oil by immobilized filamentous fungi (Tyromyces sambuceus). The combination of oriented metal screens and moving blades was found to be highly effective for a model system in maintaining stable substrate emulsion in the reactor in either batchwise or continuous processing, as well as maintaining biofilm thickness with continuous removal of excess growing hyphae. © 1996 John Wiley & Sons, Inc.
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    Immobilization of trypsin onto “molded” macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) rods and use of the conjugates as bioreactors and for affinity chromatography (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 355-363 
    Details
    ISSN: 0006-3592
    Keywords: trypsin ; immobilization ; molded support ; poly(glycidyl methacrylate-co-ethylene dimethacrylate) ; porous materials ; affinity chromatography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Trypsin immobilization onto continuous “molded” rods of porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) and some applications of the conjugate have been studied. The rods polymerized within a tubular mold (chromatographic column), were treated in situ with ethylenediamine, activated with glutaraldehyde and finally modified with trypsin. The performance of the trypsin-modified rods was evaluated and compared to that of poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, modified with the same enzyme. Overall the enzyme-modified rods performed substantially better than the corresponding beads. In particular, the performance of the molded supports as enzymatic reactors or as chromatographic media benefits greatly from the enhanced mass transfer that is characteristic of the molded rod at high flow rates. © 1996 John Wiley & Sons, Inc.
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    Kinetic evaluation of biotransformation of benzaldehyde to L-phenylacetylcarbinol by immobilized pyruvate decarboxylase from Candida utilis (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 429-436 
    Details
    ISSN: 0006-3592
    Keywords: biotransformation ; L-phenylacetylcarbinol ; immobilization ; pyruvate decarboxylase ; Candida utilis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biotransformation of benzaldehyde to L-phenylacetylcarbinol (L-PAC) as a key intermediate for L-ephedrine has been evaluated using immobilized pyruvate decarboxylase (PDC) from Candida utilis. PDC immobilized in spherical polyacrylamide beads was found to have a longer half-life compared with free enzyme. In a batch process, the immobilized PDC generally produced lower L-PAC than free enzyme at the same concentrations of substrates due to increased by-products acetaldehyde and acetoin and reduced benzaldehyde uptake. With immobilized PDC, L-PAC formation occurred at higher benzaldehyde concentrations (up to 300 mM) with the highest L-PAC concentration being 181 mM (27.1 g/L). For a continuous process, when 50 mM benzaldehyde and 100 mM sodium pyruvate were fed into a packed-bed reactor at 4°C and pH 6.5, a productivity of 3.7 mM/h (0.56 g/L · h) L-PAC was obtained at an average concentration of 30 mM (4.5 g/L). The half-life of immobilized PDC reactor was 32 days. © 1996 John Wiley & Sons, Inc.
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    Microencapsulation of yeast cells and their use as a biocatalyst in organic solvents (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 535-543 
    Details
    ISSN: 0006-3592
    Keywords: whole cell biotransformation ; biocatalyst ; baker's yeast ; immobilization ; microencapsulation ; organic solvents ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stable, semipermeable polyamide microcapsules were prepared by interfacial polymerization from a mixture of 1,6-hexanediamine and poly(allylamine) crosslinked with di-acid chlorides and were used to encapsulate baker's yeast. The size and distribution of cells within the capsules were investigated by a combination of laser confocal, electron scanning, and transmission electron microscopy. The encapsulated cells were studied as a biocatalyst for the model reduction of 1-phenyl-1,2-propanedione to 2-hydroxy-1-phenyl-1-propanone in a number of organic solvents. The polymerization conditions were extensively investigated and were found to greatly influence the product yield. Microencapsulated yeast cells, prepared under optimized conditions, carried out the reduction more efficiently than free cells as well as those immobilized in alginate and κ-carrageenan beads. The developed methodology should be broadly applicable to other biotransformations of interest. © 1996 John Wiley & Sons, Inc.
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    Efficient immobilization of lipases by entrapment in hydrophobic sol-gel materials (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 527-534 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; immobilization ; sol-gel materials ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The commercial application of lipases as biocatalysts for organic synthesis requires simple but efficient methods to immobilize the enzyme, yielding highly stable and active biocatalysts which are easy to recover. In this study, we present a novel method to achieve lipase immobilization by entrapment in chemically inert hydrophobic silica gels which are prepared by hydrolysis of alkyl-substituted silanes in the presence of the enzyme. A typical immobilization procedure uses: an aqueous solution of lipase; sodium fluoride as a catalyst; and additives like polyvinyl alcohol or proteins and alkoxysilane derivatives like RSi-(OMe)3 with R = alkyl, aryl, or alkoxy as gel precursors. The effect of various immobilization parameters like stoichiometric ratio of water, silane, type and amount of additive, type and amount of catalyst, and type of silane has been carefully studied. The new method is applicable for a wide variety of lipases, yielding immobilized lipases with esterification activities enhanced by a factor of up to 88, compared to the commercial enzyme powders under identical conditions. Studies on the stability of sol-gel immobilized lipases under reaction conditions or storage (dry, in aqueous or organic medium) revealed an excellent retention of enzymatic activity. The possible reasons for the increased enzyme activities are discussed. © 1996 John Wiley & Sons, Inc.
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    Removal of chlorophenols from wastewater by immobilized horseradish peroxidase (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 126-130 
    Details
    ISSN: 0006-3592
    Keywords: chlorophenol ; peroxidase ; immobilization ; magnetite ; immobilized enzyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilization of horseradish peroxidase on magnetite and removal of chlorophenols using immobilized enzyme were investigated. Immobilization by physical adsorption on magnetite was much more effective than that by the crosslinking method, and the enzyme was found to be immobilized at 100% of retained activity. In addition, it was discovered that horseradish peroxidase was selectively adsorbed on magnetite, and the immobilization resulted in a 20-fold purification rate for crude enzyme. When immobilized peroxidase was used to treat a solution containing various chlorophenols, p-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol, each chlorophenol was almost 100% removed, and also the removal of total organic carbon (TOC) and adsorbable organic halogen (AOX) reached more than 90%, respectively. However, in the case of soluble peroxidase, complete removal of each chlorophenol could not be attained, and in particular, the removal of 2,4,5-trichlorophenol was the lowest, with a removal rate of only 36%. © 1996 John Wiley & Sons, Inc.
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    Immobilization of Candida rugosa lipase to nylon fibers using its carbohydrate groups as the chemical link (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 327-341 
    Details
    ISSN: 0006-3592
    Keywords: Candida rugosa ; immobilization ; olive oil hydrolysis ; phenylglycidate ; glutaraldehyde ; adipic dihydrazide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aim of this study was to evaluate the immobilization of lipase from Candida rugosa on a nylon support by methods used to attach biomolecules to solid supports through their carbohydrate moieties. The carbohydrate groups were converted to dialdehydes by treatment with sodium periodate. The length of exposure and the periodate amount were optimized to the point where almost total activity retention was obtained. Tests of the immobilized enzyme showed the expressed activity to be significantly higher than the activity obtained with the unimmobilized enzyme. The use of reverse micelles as a way of delivering water to the enzyme was tested and found to give significantly higher activities. The immobilized enzyme activity was also tested with other substrates, one of which was a chiral ester. The immobilized enzyme was found to have high stereoselective efficiency and activity toward racemic methyl methoxyphenyl glycidate, a chiral intermediate used in the manufacture of the drug diltiazem. © 1996 John Wiley & Sons, Inc.
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    Xylitol production by immobilized recombinant Saccharomyces cerevisiae in a continuous packed-bed bioreactor (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 317-326 
    Details
    ISSN: 0006-3592
    Keywords: xylitol ; recombinant yeast ; immobilization ; continuous packed-bed reactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous xylitol production with two different immobilized recombinant Saccharomyces cerevisiae strains (H475 and S641), expressing low and high xylose reductase (XR) activities, was investigated in a lab-scale packed-bed bioreactor. The effect of hydraulic residence time (HRT; 1.3-11.3 h), substrate/cosubstrate ratio (0.5 and 1), recycling ratio (0, 5, and 10), and aeration (anaerobic and oxygen limited conditions) were studied. The cells were immobilized by gel entrapment using Ca-alginate as support and the beads were treated with Al3+ to improve their mechanical strength. Xylose was converted to xylitol using glucose as cosubstrate for regeneration of NAD(P)H required in xylitol formation and for generation of maintenance energy. The stability of the recombinant strains after 15 days of continuous operation was evaluated by XR activity and plasmid retention analyses. Under anaerobic conditions the volumetric xylitol productivity increased with decreasing HRT with both strains. With a recycling ratio of 10, volumetric productivities as high as 3.44 and 5.80 g/L · h were obtained with the low XR strain at HRT 1.3 h and with the high XR strain at HRT 2.6 h, respectively. However, the highest overall xylitol yields on xylose and on cosubstrate were reached at higher HRTs. Lowering the xylose/cosubstrate ratio from 1 to 0.5 increased the overall yield of xylitol on xylose, but the productivity and the xylitol yield on cosubstrate decreased. Under oxygen limited conditions the effect of the recycling ratio on production parameters was masked by other factors, such as an accumulation of free cells in the bioreactor and severe genetic instability of the high XR strain. Under anaerobic conditions the instability was less severe, causing a decrease in XR activity from 0.15 to 0.10 and from 3.18 to 1.49 U/mg with the low and high XR strains, respectively. At the end of the fermentation, the fraction of plasmid bearing cells in the beads was close to 100% for the low XR strain; however, it was significantly lower for the high XR strain, particularly for cells from the interior of the beads. © 1996 John Wiley & Sons, Inc.
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    Activation and regeneration of whole cell biocatalysts: Initial and periodic induction behavior in starved Escherichia coli after immobilization in thin synthetic films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 360-370 
    Details
    ISSN: 0006-3592
    Keywords: induction ; Escherichia coli ; biofilms ; immobilization ; protein synthesis in starved bacteria ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Activation and regeneration of whole cell biocatalytic activity via initial and subsequent induction of the lacZ gene was investigated in starved Escherichia coli using a novel synthetic biofilm. Stationary-phase bacteria were entrapped in 10-80 μm thick multi-layer films, where a copolymer of acrylic and vinyl acetate was the immobilization matrix. The E. coli were placed in a defined starvation medium containing essentially no nitrogen or carbon source and induced initially using lactose or isopropylthiogalactoside (IPTG). Subsequent inductions were performed with IPTG. Comparison studies with suspended bacteria showed that when IPTG was the initial inducing agent, induction kinetics are linear for both immobilized and suspended cells. After induction with lactose, however, a lag time is noted for suspended cells, but not for E. coli in the biofilm. Biocatalytic activity was successfully regenerated by re-inducing starved suspended cells 1-3 days after an initial induction with lactose. This regeneration was demonstrated in the synthesis of additional active β-galactosidase. However, immobilized cells could be re-induced for at least 17 days after the initial induction, and viability in the synthetic biofilms remained greater than 90%, demonstrating that periodic induction is a valuable method for extending the life of whole cell biocatalysts. © 1996 John Wiley & Sons, Inc.
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    Biological sulfate reduction using synthesis gas as energy and carbon source (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 136-144 
    Details
    ISSN: 0006-3592
    Keywords: sulfate-reducing bacteria ; biofilm ; immobilization ; gas-lift reactor ; carbon monoxide ; synthesis gas ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biological sulfate reduction was studied in laboratory-scale gas-lift reactors. Synthesis gas (gas mixtures of H2/CO/CO2) was used as energy and carbon source. The required biomass retention was obtained by aggregation and immobilization on pumice particles. Special attention was paid to the effect of CO addition on the sulfate conversion rate, aggregation, and aggregate composition.Addition of 5% CO negatively affected the overall sulfate conversion rate; i.e., it dropped from 12-14 to 6-8 g SO2-4/L day. However, a further increase of CO to 10 and 20% did not further deteriorate the process. With external biomass recycling the sulfate conversion rate could be improved to 10 g SO2-4/L day. Therefore biomass retention clearly could be regarded as the rate-limiting step. Furthermore, CO affected the aggregate shape and diameter. Scanning electron microscopy (SEM) photographs showed that rough aggregates pregrown on H2/CO2 changed into smooth aggregates upon addition of CO. Addition of CO also changed the aggregate Sauter mean diameter (d32) from 1.7 mm at 5% CO to 2.1 mm at 20% CO. After addition of CO, a layered biomass structure developed. Acetobacterium sp. were mainly located at the outside of the aggregates, whereas Desulfovibrio sp. were located inside the aggregates. © 1996 John Wiley & Sons, Inc.
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    Covalent binding of a nerve agent hydrolyzing enzyme within polyurethane foams (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 450-457 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; immobilization ; phosphotriesterase ; polyurethane foam ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A phosphotriesterase preparation, extracted from Escherichia coli DH5α cells, was immobilized within a polyurethane foam matrix during polymer synthesis. The enzyme-foam interaction was shown to be covalent and analysis of the hydrolysis of paraoxon in aqueous solution demonstrated that more than 50% of the initial enzyme specific activity was retained after immobilization in the foam. Factors affecting the rate of paraoxon degradation include foam hydrophobicity, the degree of mixing applied to initiate polymerization, and foam pretreatment prior to use in substrate hydrolysis. The storage stability of the foam is significant, with phosphotriesterase-foam activity profiles exhibiting a three month half-life. Foams are currently being developed for biocatalytic air filtering, in which gaseous substrates will be simultaneously adsorbed and degraded by the immobilized enzyme system. © 1996 John Wiley & Sons, Inc.
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    The use of confocal scanning laser microscopy and other tools to characterize Escherichia coli in a high-cell-density synthetic biofilm (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 340-356 
    Details
    ISSN: 0006-3592
    Keywords: laser microscopy, confocal scanning ; Escherichia coli ; biofilms ; immobilization ; confocal scanning laser microscopy ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Properties of a novel, synthetic biofilm were examined by using confocal scanning laser microscopy (CSLM) in combination with fluorescent probes and by investigating total protein content and specific β-galactosidase activity during various steps of the biofilm preparation. Viable, but nongrowing Escherichia coli were entrapped in 10- to 80-μm-thick multilayer films, where a copolymer of acrylic and vinyl acetate was the immobilization matrix. Cell viability and distribution within the films were evaluated by developing a protocol to stain the bacteria with fluorescein isothiocyanate and propidium iodide, thereby labeling all cells green and dead cells red, respectively. Confocal microscopy facilitated viewing samples in the XY and XZ planes, and image analysis enabled counting of the cells. These experiments showed that the initial viability of the entrapped bacteria was 85% to 90%, cell distribution was uniform in the XY plane and cell number increased with increasing depth into the film. Specific β-galactosidase assays developed here allowed comparison of the induction of lacZin suspended and immobilized cells. These experiments demonstrated that rehydration was an important step in biofilm preparation, and E. coli cast into synthetic biofilms with cell layers of at least 20 to 35 μm in thickness had gene induction characteristics similar to suspended cells. © 1996 John Wiley & Sons, Inc.
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    Increased H2 production by immobilized microorganisms (1995)
    Springer
    World journal of microbiology and biotechnology 11 (1995), S. 156-159 
    Details
    ISSN: 1573-0972
    Keywords: Bacillus ; biogas-H ; hydrogen ; immobilization ; mixed culture ; recycling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Viable cells of H2-producers (Bacillus licheniformis and a mixed microbial culture) were immobilized on brick dust and in calcium alginate beads. In batch culture, cells of the mixed culture in the free state yielded 8.2 l H2/mol glucose utilized, whereasB. licheniformis evolved 13.1 l H2. Immobilized cells, however, gave 4-fold more H2 than the free bacteria. Highest yields were from the cells immobilized on brick dust. High H2-production rates continued over two rounds of re-use of the immobilized cells.
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    URL: http://dx.doi.org/10.1007/BF00704638
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    Removal of phenols and aromatic amines from wastewater by a combination treatment with tyrosinase and a coagulant (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 304-309 
    Details
    ISSN: 0006-3592
    Keywords: phenol ; substituted phenol ; tyrosinase ; immobilization ; chitosan ; coagulant ; immobilized enzyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal of phenols and aromatic amines from industrial wastewater by tyrosinase was investigated. A color change from colorless to darkbrown was observed, but no precipitate was formed. Colored products were found to be easily removed by a combination treatment with tyrosinase and a cationic polymer coagulant containing amino group, such as hexamethylenediamine-epichlorohidrin polycondensate, polyethleneimine, or chitosan. The first two coagulants, synthetic polymers, were more effective than chitosan, a polymer produced in crustacean shells. Phenols and aromatic amines are not precipitated by any kind of coagulants, but their enzymatic reaction products are easily precipitated by a cationic polymer coagulant. These results indicate that the combination of tyrosinase and a cationic polymer coagulant is effective in removing carcinogenic phenols and aromatic amines from an aqueous solution. Immobilization of tyrosinase on magnetite gave a good retention of activity (80%) and storage stability i.e., only 5% loss after 15 days of storage at ambient temperature. In the treatment of immobilized tyrosinase, colored enzymatic reaction products were removed by less coagulant compared with soluble tyrosinase. © 1995 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bit.260450404
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    Photochemistry of a photosynthetic reaction center immobilized in lipidic cubic phases (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 93-98 
    Details
    ISSN: 0006-3592
    Keywords: photosynthetic reaction center ; liquid crystals ; cubic phases ; immobilization ; Chloroflexus aurantiacus ; photochemistry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Photosynthetic reaction centers, isolated and purified from the facultative phototrophic bacterium Chloroflexus aurantiacus, were immobilized in optically transparent lipidic cubic phases composed of 42% (w/w) 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine and 58% (w/w) water. The immobilized photosynthetic protein retains its native properties, as indicated by visible and circular dichroic spectra. The ground state visible spectrum of the immobilized reaction centers is very similar to the corresponding spectrum in aqueous solution, indicating that the protein pigments are not extracted into the lipidic regions of the cubic phase. The secondary structure of the protein is maintained in the immobilized state, as determined by far-UV circular dichroism spectroscopy in the 200- to 250-nm range. Moreover, immobilized reaction centers retain their photochemical activity: a reversible photo-oxidation of the primary electron donor (P) is seen upon continuous illumination. Furthermore, the entrappment of reaction centers does not affect the kinetics of charge recombination between the photo-oxidized primary donor (P+) and the photoreduced primary quinone acceptor, generated by a short flash of light. Reaction centers devoided of the secondary quinone acceptor can be easily reconstituted in cubic phases by means of their coimmobilization with 1,4-naphtoquinone. Indeed, the kinetics for charge recombination in reconstituted reaction centers is dramatically slower than the corresponding kinetics in the unreconstituted protein. Interestingly, immobilized reaction centers are significantly stabilized as compared with reaction centers in aqueous solution: the integrity of the protein in the cubic phase is maintained for at least 5 months, whereas in water solution 50% of the activity is lost within 2 months. © 1995 John Wiley & Sons, Inc.
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    Selective adsorption of proteins to their ligands covalently immobilized onto microfibers (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 557-566 
    Details
    ISSN: 0006-3592
    Keywords: polyester fiber ; immobilization ; protein A ; antigen ; antibody ; immunoadsorbent ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Following ozone oxidation of polyester microfibers of 3.5 μm average diameter and 0.83 m2/g specific area, the fiber surface was subjected to graft polymerization of acrylic acid and subsequently immobilized with serologically active proteins including Staphylococcus aureus protein A, a specific antigen, and a specific antibody. The immobilization reaction was mediated by a watersoluble carbodiimide, which allowed formation of a co-valent linkage between the ligand proteins and the grafted poly(acrylic acid)chains. The yields of the immobilized ligand proteins were of the order of 1 mg/g fiber. Their binding affinity and capacity to respective specific proteins were studied in vitro from a buffered solution and serum. It was found that the specific proteins were selectively adsorbed with dissociation constants as low as 1× 10-6 M, suggesting the adsorption to take place through highly specific protein-protein interaction. An addition of serum albumin did not significantly affect the specific binding, regardless of the ligand proteins. The binding capacity ranged from 1 × 10-13 to 1× 10-11 mol/cm2 primarily depending on the surface density of the immobilized ligands and the number of their binding sites per molecule. © 1995 John Wiley & Sons Inc.
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    URL: http://dx.doi.org/10.1002/bit.260470508
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    Serum-free cell culture on insulin-immobilized porous collagen beads (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 144-148 
    Details
    ISSN: 0006-3592
    Keywords: serum-free cell culture ; cell adhesion ; cell growth ; fibroblast cell ; biosignal ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Insulin or albumin was immobilized on collagen beads using water-soluble carbodiimide. Adhesion of STO mouse fibroblast cells onto the beads decreased with increasing the amount of immobilized proteins. Growth of the cells was remarkably accelerated on the insulinimmobilized collagen beads, which can be used for serum-free cell culture. The growth acceleration became larger with increasing the amount of immobilized insulin, while it became smaller with increasing the amount of immobilized albumin. In addition, the immobilized insulin more strongly accelerated the cell growth than free insulin plus collagen beads. © 1995 John Wiley & Sons, Inc.
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    Synthesis of protein-containing polymers in organic solvents (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 10-17 
    Details
    ISSN: 0006-3592
    Keywords: proteins ; enzymes ; immobilization ; biopolymers ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Subtilisin has been modified with polyethylene glycol (PEG) monomethacrylate (MW 8000) by reductive alkylation, and incorporated into polymethyl methacrylate durring free-radical initiated polymerization. The activity and stability of the PEG-modified enzymes have been determined in aqueous buffer and organic solvents. The Km and Vmax values for unmodified, singly and doubly modified subtilisin were compared in these environments, and the half-lives of both modified enzymes were remarkably high (up to 2 months). The protein-containing polymer was analyzed for activity and polymer properties, and our results indicate that active subtilisin can be incorporated into polymethyl methacrylate during polymerization in organic solvents while retaining its activity and stability. © 1995 John Wiley & Sons, Inc.
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    The viability of Scenedesmus bicellularis cells immobilized on alginate screens following nutrient starvation in air at 100% relative humidity (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 459-464 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; screens ; microalgae ; Scenedesmus bicellularis ; starvation in air ; relative humidity ; wastewater treatment ; nutrient uptake ; viability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The viability of algal cells immobilized on screens and starved in a water-saturated air stream was studied at the laboratory scale. This new process for wastewater biotreatment has been developed using immobilized cells, which were starved in air, to obtain a high rate of nutrient removal. A unicellular green microalgae, Scenedesmus bicellularis, was isolated from secondary decantation tanks at an urban wastewater treatment plant and grown in a synthetic medium for 12 days. The cells were then concentrated by centrifugation and immobilized on alginate screens. The screens were then inserted in a photochamber saturated at 100% relative humidity and subjected to a photoperiod of 16 h in the light and 8 h in the dark, with an illumination of 150 μE m-2 s-1 provided by fluorescent lamps. After 48 h of nutrient starvation, the immobilized cells were used for the removal of ammonium and orthophosphate from a synthetic secondary wastewater effluent in a plexiglass reactor. During the sequential operation of starvation followed by incubation in the presence of nutrients, fast growth of viable cells in the gel matrix was obtained and there was no appreciable decay of chlorophyll a or cell activity. When these immobilized and starved cells were incubated in wastewater, ammonium (NH4+) and orthophosphate (PO43-) ions were quickly taken up from medium. After three successive 2-h exposures to wastewater, immobilized algal cells were freed by dissolving the Ca-alginate with phosphate as 0.2 M Na3PO4 and resuspended in fresh culture medium. Results indicate that free cells transferred to rich medium remained viable, but the growth rate revealed that the viable cells decreased their culturability. © 1995 John Wiley & Sons, Inc.
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    Enhancement of monoclonal antibody production by immobilized hybridoma cell culture with hyperosmolar medium (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 699-705 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; hyperosmotic stress ; immobilization ; antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To determine the effect of hyperosmotic stress on the monoclonal antibody (MAb) production by calcium-alginate-immobilized S3H5/γ2bA2 hybridoma cells, the osmolalities of medium in the MAb production stage were varied through the addition of NaCI. The specific MAb productivity (qMAb) of immobilized cells exposed to abrupt hyperosmotic stress (398 mOsm/kg) was increased by 55% when compared with that of immobilized cells in the control culture (286 mOsm/kg). Furthermore, this enhancement of qMAb was not transient. Abrupt increase in osmolality, however, inhibited cell growth, resulting in no increase in volumetric MAb productivity (rMAb). On the other hand, gradual increase in osmolality allowed further cell growth while maintaining the enhanced qMAb immobilized cells. The qMAb immobilized cells at 395 mOsm/kg was 0.661 ± 0.019 μg/106 cells/h, which is almost identical to that of immobilized cells exposed to abrupt osmotic stress. Accordingly, the rMAb was increased by ca. 40% when compared with that in the control immobilized cell culture. This enhancement in iMAb of immobilized S3H5/γ2bA2 hybridoma cells by applying gradual osmotic stress suggests the potential of using hyperosmolar medium in other perfusion culture systems for improved MAb production. © 1995 John Wiley & Sons, Inc.
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    Studies on the lipozyme-catalyzed synthesis of butyl laurate (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 1-12 
    Details
    ISSN: 0006-3592
    Keywords: Lipozyme ; esterification ; immobilization ; butanol ; lauric acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of temperature, speed of agitation, enzyme concentration, etc., on butyl laurate synthessis using Mucor miehei lipase (Lipozyme™) have been studied. Although the soluble enzyme was quite thermcstable in aqeous solution, it deactivated rapidly at and above 40°C in the presence of butanol. This enzyme immobilized on an anion-exchange resin (Lipozyme™) showed enhanced stability (as compared to the soluble form) to denaturation by butanol under the same conditions. The denaturation of M. miehei lipase was found to be a function of the butanol concentration in the aqueous phase, and rapid denaturation takes place at the concentration corresponding to its saturation at that temperature. © 1995 John Wiley & Sons, Inc.
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    Immobilization of Anabaena azollae from Azolla filiculoides in polyvinyl foam for ammonia production in a photobioreactor system (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 55-58 
    Details
    ISSN: 1573-0972
    Keywords: Ammonia excretion ; Anabaena azollae (AS-DS) ; Benlate ; immobilization ; MSX ; photobioreactor ; polyvinyl foam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Anabaena azollae (AS-DS), isolated from Azolla filiculoides and grown in nitrogen-free medium, was immobilized in 5-mm-cube polyvinyl foam pieces and incorporated into a photobioreactor system for the production of NH3. NH3 was produced continuously and in significant amounts. Benlate (methyl-1-butyl-carbamoyl)-2-benzimidazole carbamate at 5 ppm and l-methionine-d,l-sulphoximine at 50 μm stimulated NH3 production continuously for a period of 1 week.
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    Novel protein a affinity matrix prepared from two-dimensional protein crystals (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 321-330 
    Details
    ISSN: 0006-3592
    Keywords: crystalline surface layers ; Protein A ; immobilization ; affinity matrix ; Clostridium thermohydrosulfuricum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this article, we describe a novel type of affinity matrix which was prepared by covalently binding Protein A to crystalline cell surface layers (S-layers) from the gram-positive Clostridium thermohydrosulfuricum L111-69. S-layers were used in the form of cell wall fragments, which were obtained by breaking whole cells by ultrasonification and removing the cell content and the plasma membrane. In these thimble shaped structures, revealing a size of 1 to 2 μm, the peptidoglycan-containing layer was covered on both faces with a hexagonally ordered S-layer lattice composed of identical glycoprotein subunits. After crosslinking the S-layer protein with glutaraldehyde, carboxyl groups from acidic amino acids were activated with carbodiimide and used for immobilization of Protein A. Quantitative determination confirmed that up to two Protein A molecules were bound per S-layer subunit leading to a dense monomolecular coverage of the immobilization matrix with the ligand.Affinity microparticles were capable of adsorbing lgG from solutions of purified preparations, from artificial lgG-albumin mixtures, and from serum. The amount of lgG bound to affinity microparticles corresponded to the theoretical saturation capacity. Under appropriate conditions, up to 95% of the adsorbed lgG could be eluted again. Affinity microparticles were found to have an extremely low Protein A leakage and a high stability toward mechanical forces. Because pores in the S-layer lattice revealed a size of 4 to 5 nm, immobilization of Protein A and adsorption of lgG was restricted to the outermost surface area. This excludes mass transfer problems usually encountered with affinity matrices prepared from amorphous polymers where more than 90% of the ligands are immobilized in the interior. © 1994 John Wiley & Sons, Inc.
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    Blueprint for a lipase support: Use of hydrophobic controlled-pore glasses as model systems (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 934-938 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; nonaqueous enzymology ; esterification ; Rhizomucor miehei lipase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the commercial exploitation of lipase biocatalysis to be successful, it is essential that effective supports are selected for lipase immobilization. In this study hydrophobic controlled-pore glasses have been used as model systems for the immobilization of Rhizomucor miehei lipase. The effect of pore diameter and surface chemistry on enzyme efficiency in a typical esterification reaction under essentially nonaqueous conditions has been examined. It has been found that pore diameters of at least 35 nm are needed for the lipase to be able to utilize the internal volume of the support particles in the immobilization process. Despite the small size of the substrates in the esterification reaction, even larger pores (〉100 nm) are required for the lipase efficiency to become independent of pore diameter; below 100 nm lipase activity and efficiency are markedly reduced. It has also been shown that the chemical nature of the hydrophobic surface plays an important part in catalyst design. Although lipase will adsorb readily to a wide range of hydrophobic groups, the highest catalyst activities are obtained when the glass surface is derivatized to give long alkyl chains; the presence of unsaturated derivatives gonerally leads to a reduction in activity. © 1994 John Wiley & Sons, Inc.
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    Production of lignin peroxidase by Phanerochaete chrysosporium immobilized on porous poly(styrene-divinylbenzene) carrier and its application to the degrading of 2-chlorophenol (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 79-86 
    Details
    ISSN: 0006-3592
    Keywords: lignin peroxidase ; Phanerochaete chrysosporium ; white-rot-fungus ; polymers ; immobilization ; 2-chilorophenol ; biodegradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Porous poly(styrene-divinylbenzene) carriers, for the immobilization of white rot fungus Phanerochaete chrysosporium have been prepared by the concentrated emulsion polymerization method. The concentrated emulsion consists of a mixture of styrene and divinylbenzene containing a suitable surfactant and an initiator as the continuous phase, and water as the dispersed phase. The polymerization of the monomers of the continuous phase generated the polymer carrier with a porcus structure. The white rot fungus Phanerochaete chrysosporium has been immobilized on porous poly(styrene-divinylbenzene) carriers and used for the batch production and the repeated batch production of lignin peroxidase in shake cultures based on a carbon-limited medium containing veratryl alcohol. The best results were achieved when a spore inoculum was used for immobilization instead of 1-day-old mycelial pellets, for both the batch production and the repeated batch production. The porous poly(styrene-divinylbenzene) immobilized Phanerochaete chrysosporium and freely suspended mycelial pellets were used as biocatalysts for the degradation of 2-chilorophenol in a 2-L bioreactor. The porous poly(styrene-divinylbenzene) particle (diameter ≅ 0.2 cm) immobilized spores exhibited a much higher activity in the degradation of 2-chlorophenol than the freely suspended mycelial pellets. © 1994 John Wiley & Sons, Inc.
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    Long-Term continuous culture of hepatocytes in a packed-bed reactor utilizing porous resin (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 635-644 
    Details
    ISSN: 0006-3592
    Keywords: hepatocytes ; artificial liver ; long-term culture ; packed-bed reactor ; porous resin ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As part of our attempt to develop a hybrid artificial liver support system using cultured hepatocytes, we investigated the long-term metabolic function of hepatocytes incubated in a packed-bed type reactor using reticulated polyvinyl formal (PVF) resin as a supporting material. Long-term (up to 1 week) perfusion culture experiments using the packed-bed reactor (20 mm i.d.) loaded with 500 PVF resin cubes (mean pore size 250 μm, 2 × 2 × 2 mm), together with conventional monolayer culture experiments as controls, were performed in serum-free or serum-containing medium. Ammonium metabolism and urea synthesis activities were evaluated quantitatively based on reaction kinetic analyses. Initial rates of ammonium metabolism and urea-N synthesis, as well as GPT enzyme activities, were adopted as indexes of the metabolic performance of the reactor and activities of the cultured hepatocytes.When serum-free medium was used in the perfusion cultures, ammonium metabolic and urea-N synthetic rates showed significant decay with elapse of the culture period, being less than 10% of those measured on day 1. This loss of activity was more prominent in the perfusion culture than in the monolayer cultures using this medium. In contrast, when serum-containing medium was used, approximately 50% of these activities obtained on day 1 were maintained even at the end of the cultures both in the perfusion and monolayer culture experiments.We concluded that the packed-bed reactor using PVF resin enabled high-density culture of hepatocytes, and showed a satisfactory ability to maintain the metabolic function of immobilized hepatocytes for relatively long periods of up to 1 week. This type of reactor is thus considered to represent a breakthrough in overcoming the difficulties involved in the development of a hybridtype artificial liver support system. © 1994 John Wiley & Sons, Inc.
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    Change in growth kinetics of hybridoma cells entrapped in collagen gel affected by alkaline supply (1994)
    Springer
    Cytotechnology 14 (1994), S. 129-146 
    Details
    ISSN: 1573-0778
    Keywords: growth kinetics ; growth yield ; collagen ; fluidized bed reactor ; immobilization ; alkali supply
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The growth yields for glucose and glutamine of murine hybridoma cells entrapped in collagen gel particles were examined during the growth phase. The immobilized hybridoma cells were cultivated in a fluidized bed fermenter where the medium was circulating to supply oxygen separately. Procedures to supply an alkaline solution for adjusting the pH level strongly affected the growth yields. A direct supply of the alkaline solution to the cultivation system reduced both the growth yields for glucose and glutamine, probably due to a local increase in pH level. On the other hand, when fresh medium in which the pH was adjusted to around 8.5 was added to the cultivation system, the growth yields were unchanged even at the same pH level as when direct alkaline supply was used. These results suggest that an indirect alkaline supply could be recommended to ajust the pH level when using medium-circulating-fermenters.
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    Enhanced specific antibody productivity of calcium alginate-entrapped hybridoma is cell line-specific (1994)
    Springer
    Cytotechnology 16 (1994), S. 1-15 
    Details
    ISSN: 1573-0778
    Keywords: Flow cytometry ; hybridoma ; immobilization ; specific antibody productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In order to determine whether the enhanced specific antibody productivity (q MAb ) of calcium alginate-entrapped hybridoma is cell line-specific, calcium alginate-entrapped hybridomas (4A2 and DB9G8) were cultivated under the condition where we had previously observed significantly enhancedq MAb of calcium alginate-entrapped S3H5/γ2bA2 hybridoma. Unlike S3H5/γ2bA2 hybridoma, neither 4A2 nor DB9G8 hybridomas showed persistently enhancedq MAb when they were entrapped in calcium alginate beads. The enhancedq MAb of entrapped 4A2 and DB9G8 hybridomas, which was 2–3 times higher than theq MAb of free-suspended cells in a control experiment, was observed only during the early stage of the culture. During the early stage of the culture, the viable cell concentration decreased probably due to cell damage during the entrapment process. As cell growth resumed, theq MAb decreased to the similar level ofq MAb of free-suspended cells within 5–7 days. Thus, we conclude that the enhancedq MAb of calcium alginate-entrapped hybridomas is cell line-specific.
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    Potential applications of viable, immobilized fungal cell systems (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 495-502 
    Details
    ISSN: 1573-0972
    Keywords: Fungi ; immobilization ; potential applications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Immobilized cell technology attracts considerable attention because of the many advantages it offers over conventional suspended-cell fermentations. Important advances continue to be made in the potential use of immobilized cells as biocatalysts. This review is mainly devoted to the analysis of recent literature on the applications of immobilized fungal cell systems, ranging from the production or transformation of useful compounds (e.g. organic acids, enzymes, antibiotics, steroids, etc.) to wastewater treatment. The problems and future industrial applications are also discussed.
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    Immobilization of Zymomonas mobilis 2716, for the protection of cellular activity (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 366-371 
    Details
    ISSN: 1573-0972
    Keywords: Alginate ; freeze-substitution ; immobilization ; Zymomonas mobilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Alginate-immobilized Zymomonas mobilis cells produced 17.8% (v/v) ethanol in less than 24 h, with an ethanol yield of 97%, compared with 88% for free cells, using a fed-batch cultivation technique. The substrate, glucose, was added intermittently in powder form to foster nucleation of the CO2 formed. Repeated-batch cultivation led to complete utilization of approximately 200 g glucose/l in 7.5 h with a 98% conversion efficiency to ethanol. Free cells used the glucose less efficiently (conversion efficiency of 78%), and even after 100 h the glucose was not fully consumed. Freeze-substitution electron microscopy studies showed that immobilized cells generally displayed lesser blebbing and membrane disruption than free cells. These studies further suggest that membrane blebbing may be due to an effect of high initial glucose levels, and not due to the accumulation of end-products ethanol and CO2.
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    Degradation of nitriles and amides by the immobilized cells of Pseudomonas putida (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 483-486 
    Details
    ISSN: 1573-0972
    Keywords: Acetonitrile ; amides ; biodegradation ; immobilization ; nitriles ; Pseudomonas putida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Pseudomonas putida, capable of utilizing acetonitrile as a sole source of C and N, was immobilized in calcium alginate and the rates of degradation of nitriles, including acetonitrile, and their respective amides were studied. All the organic nitriles and amides tested were converted into NH3 and CO2.
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    Immobilization of milk-clotting proteases (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 139-144 
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    ISSN: 1573-0972
    Keywords: Cheese ; immobilization ; milk-clotting enzymes ; proteases ; rennet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Traditionally, cheese manufacturing is a batch process and current practice is to use a milk-clotting enzyme in a soluble form. Immobilization of proteases for milk coagulation has received renewed interest and potential applications have recently been reported. Use of immobilized proteases would permit renneting of milk as a continuous process. In addition, it should be possible to recover and re-use the enzyme for coagulation of further batches of milk. This review elaborates on the recent developments in the area of immobilized proteases and their application in cheese-making.
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    Properties of Aspergillus japonicus β-fructofuranosidase immobilized on porous silica (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 216-220 
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    ISSN: 1573-0972
    Keywords: Aspergillus ; β-fructofuranosidase ; fructo-oligosaccharide ; immobilization ; porous silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract β-Fructofuranosidase from Aspergillus japonicus MU-2, which produces fructo-oligosaccharides (1-kestose: O-β-D-fructofuranosyl-(2 → 1)-β-D-fructofuranosyl α-D-glucopyranoside); and nystose: O-β-D-fructofuranosyl-(2 → 1)-β-D-fructofuranosyl-(2 → 1)-β-D-fructofuranosyl α-D-glucopyranoside) from sucrose, was immobilized, covalently with glutaraldehyde onto alkylamine porous silica, at high efficiency (64%). Optimum pore diameter of porous silica for immobilization of the enzyme was 91.7 nm. After immobilization, the enzyme's stabilities to temperature, metal ions and proteolysis were improved, while its optimum pH and temperature were unchanged. The highest efficiency of continuous production of fructo-oligosaccharides (more than 60%), using a column packed with the immobilized enzyme, was obtained at 40% to 50% (w/v) sucrose. The half-life of the column during long-term continuous operation at 55°C was 29 days.
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    Influence of culture density, pH, organic acids and divalent cations on the removal of nutrients and metals by immobilized Anabaena doliolum and Chlorella vulgaris (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 196-201 
    Details
    ISSN: 1573-0972
    Keywords: Anabaena doliolum ; calcium ; Chlorella vulgaris ; heavy metals ; immobilization ; magnesium ; organic acids ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The potential of alginate-immobilized Anabaena doliolum and Chlorella vulgaris was assessed for removal of nutrients (NO inf3 sup- and NH inf4 sup+ ) and metals (Cr2O inf7 sup2- and Ni2+) at different biomass concentrations (0.05, 0.1, 0.25, 0.49 and 1.22 g dry wt l-1) and pH values (4 to 10). Though uptake of all these substances was higher in concentrated algal beads (0.25, 0.49 and 1.22 g dry wt l-1), their rate of uptake was significantly (P〈0.001) lower than that of low (0.05 g dry wt l-1) cell density beads. For A. doliolum, there was no significant difference in uptake rates for beads having densities of 0.05 and 0.1 g dry wt l-1. Chlorella vulgaris, however, showed maximum efficiency at 0.1 g dry wt l-1. Uptake of both the nutrients and the metals was maximal at pH 7 followed by pH 8, 6, 9, 10, 5 and 4. Of the different substances (organic acids and divalent cations) used, humic acid was most efficient in decreasing metal uptake. Mg2+ was, however, more efficient than Ca2+ in decreasing Ni2+ uptake. Immobilized algae with a cell density of 0.1 g dry wt l-1 were the most efficient for nutrient and metal removal at pH 6 to 8.
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    Stability of antibody productivity is improved when hybridoma cells are entrapped in calcium alginate beads (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1131-1135 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; instability ; immobilization ; monoclonal antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Loss of monoclonal antibody (MAb) productivity in long-term, free-suspended cell culture is often attributed to the appearance of a nonproducing population of hybridoma cell (NP) in the culture which has a growth advantage over the producing population (P). However, when an NP appears in long-term culture of entrapped cells, it may not be able to take over the whole culture in a short period of time due to the limited growth of the entrapped cells. In order to examine the hypothesis that entrapped cells can have improved stability of MAb productivity due to limited cell growth, free-suspended cell culture and calcium alginate-entrapped cell culture with inocula consisting of a P and an NP were compared with regard to stability of MAb productivity in a repeated fed-batch culture. In free-suspended cell culture, the NP appeared to take over the whole culture within three batches, and thereby MAb production completely disappeared. In entrapped cell culture, an NP appeared to outgrow the P rapidly only during an exponential growth phase, resulting in a significant decrease in specific MAb productivity, qMAb, from 11.58 μg/106 cell/day to 2.76 μg/106 cell/day. However, when the cell growth was limited in entrapped cell culture, the NP no longer outgrew the P rapidly, as indicated by the stable value of qMAb. In addition, when the cells recovered from the alginate beads by citrate buffer treatment were subcultured in free-suspended cell culture, MAb production rapidly deteriorated and completely disappeared within two batches. Thus, the P present at a small fraction of viable cell concentration in the beginning of the free-suspended cell culture, which were previously entrapped in alginate beads, seemed to be outgrown rapidly by the NP. Taken together, the results obtained from these experiments support the hypothesis that the limited cell growth in entrapped cell culture, which keeps an NP from taking over the whole culture, is responsible, in part, for the improved stability of MAb productivity. © 1993 John Wiley & Sons, Inc.
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    Immobilization of lipase for effective interesterification of fats and oils in organic solvent (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 204-210 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; interesterification ; cocoa butter equivalent ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to investigate quantitatively the interesterification reaction, triolein and stearic acid were used as substrates and eight commercially available lipases were tested for their suitability for the reaction. Three fungal lipase preparations were found to be suitable. The hydrolytic activity of the commercial lipases was tested with olive oil, and it 2was noted that there was no correlation between their hydrolytic and interesterification activities. Among the lipases tested, Mucor miehei lipase was chosen for further study because of it high protein content and its relatively high hydrolytic and interesterification activities, both of which are required for effective interesterification. The effect of water activity of the interesterification reaction was investigated. interesterification activity was shown to be maximum at the water activity of 0.25. As the water activity of the lipase increased, hydrolysis of triglyceride was accelerated. At zero water activity, high conversion was achieved, although interesterification activity was relatively lower than that at the water activity of 0.25. A new and simple immobilization method was developed in order to render hydrophobicity to the lipase and hence to improve the interesterification activity of the lipase. The lipase was immobilized covalently with glutaraldehyde or with six alkyl chains as spacers onto Florisil (magnesium silicate, a inorganic matrix). Interesterification activity of the immobilized lipase with the hydrophobic spacers were increased against that of re lipase. The increase of activity was up to 8-fold that of the original activity of free lipase when the spacer was 7-aminoheptanoic acids. Relatively high stability of the immobilized lipase was shown in a continuous packed bed column reactor with a half-life of 97 days. © 1993 John Wiley & Sons, Inc.
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    The adsorptive immobilization of phospholipids D mediated by calcium ions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 833-836 
    Details
    ISSN: 0006-3592
    Keywords: phospholipase D ; adsorptive immobilization ; calcium ; stabilization ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilization of phospholipase D from cabbage was studied with the aim of stabilizing the enzyme for its use in synthesis of phospholipids. It was shown that phospholipase D can be immobilized by adsorption to polymeric carriers containing long chain anchor groups such as octadecyl, octyl, or other alkyl residues. Starting from the crude enzyme, phospholipase D activity is preferentially bound (up to 100%) in competition with contaminating proteins. A prerequisite of high binding rates is the presence of calcium ions, which play a mediating role in the adsorption process. The maximum activity of the carrier-enzyme complexes depends upon the calcium concentration in the immobilization process and the carrier material (≥10mM CaCl2 with octadecyl-Si40, ≥40 mM CaCl2 with octyl-sepharose and butyl-fractogel). Immobilization of phospholipase D to octyl-sepharose was shown to result in a distinctly increased storage stability and an enlarged pH-optimum range for the catalytic activity. Operational stability of different phospholipase D-carrier complexes was compared. © 1993 Wiley & Sons, Inc.
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    A bioassay of thyrotrophin by photografted mammalian cells onto polymeric supportsPart 28 of the series “Photosynthetic Membranes.” (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 255-259 
    Details
    ISSN: 0006-3592
    Keywords: thyroid cells ; immobilization ; photografting ; photocatalyst ; thryrotrophin bioassay ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Viable and functionally responsive human thyroid follicular cells, suspended in a commercial polyester acrylate diluted with tripropyleneglycol diacrylate, photoinitiated, and photocatalyzed with a proprietary photocatalytic system based on a synergic mixture of vanadium (V) t-butoxide and i-propoxide, have been immobilized as monolayers onto polystyrene plates. Bioassay of thyrotrophin in immobilized cell cultures yielded, by log-log plot of the dose-response curve, a slope (0.92 ± 0.02) in close agreement with that (0.91) reported for cells immobilized by physical adsorption. The decisive role of photocatalyst in the photografting procedure has also been shown experimentally. A mechanism is suggested by which cells are anchored, rapidly and with stable chemical bonds, onto one of the two acrylate functions of the monomer-prepolymer mixture, the other one being simultaneously responsible for photochemical grafting onto the support. © 1993 John Wiley & Sons, Inc.
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    Analytical effectiveness calculations concerning the degradation of an inhibitive substrate by a steady-state biofilm (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 267-278 
    Details
    ISSN: 0006-3592
    Keywords: biocatalyst ; immobilization ; analytical effectiveness factor ; substrate inhibition ; phenol degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A reaction engineering model for the degradation of an inhibitory substrate by a steady-state biofilm is presented. The model describes both the metabolic rate controlling behavior of this substrate in the biofilm and the effect of diffusion limitation caused by an arbitrary substrate on the active biofilm thickness. An analytical expression for the biocatalyst effectiveness factor is presented on the basis of Pirt kinetics for cell maintenance, first order substrate inhibition kinetics, and zero order substrate consumption kinetics. The proposed expression for the biocatalyst effectiveness factor is much more convenient to incorporate into a macroreactor model than the numerical alternatives. Simple criteria are presented to check the applicability of the model in case of true Monod kinetics. The analytical solution is expected to be particularly applicable to processes where a low soluble organic substrate controls the biomass growth, a situation which is often met in wastewater purification processes of industrial importance. The degradation of phenol by Pseudomonas sp. is treated as an example. © 1993 John Wiley & Sons, Inc.
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    Improved activity retention of enzymes deposited on solid supports (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 171-178 
    Details
    ISSN: 0006-3592
    Keywords: enzyme stabilization ; additive ; immobilization ; support material ; organic media ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymes deposited on solid support usually show good stability when operated in organic solvents. Decreased stability of the enzyme preparations was noticed when low enzyme loadings were used (e.g., with Celite as support; less than 1 mg enzyme/g). It was possible to avoid the activity loss by the addition of an additive which protects the enzyme during the immobilization. Proteins (such as albumin, gelatin, and casein) and poly(ethylene glycol) were effective additives whereas amino acids, monomeric carbohydrates, and polysaccharides had no effect. The amount of additive needed for stabilization was shown to depend on the structure of the support, more additive being required for a support with high porosity. The stabilizing effect was investigated in a series of glyceryl-controlled-pore glass (CPG) with varying specific surface areas (9.5-180 m2/g). The minimum addition of albumin, giving full stabilization, on the different supports correlated to a monolayer coverage of the surface, approximately 2-3 mg protein/m2. The effect of the additive was less pronounced when increasing amounts of enzyme were immobilized (5-40 mg enzyme/g Celite). The effect of the additives was studied using mandelonitrile lyase, but α-chymotrypsin and lipase P were also shown to be stabilized. © 1993 John Wiley & Sons, Inc.
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    Immobilization of enzyme onto cellulose-titanium oxide composite fiber (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 394-397 
    Details
    ISSN: 0006-3592
    Keywords: cellulose ; immobilization ; fiber ; titanium oxide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fibers of a cellulose-TiO2 composite were prepared by the reaction of cellulose with titanium iso-propoxide. Enzymes were immobilized on the fibers easily and simply under mild conditions. The fibers were stable in common solvents, high ionic solutions, and over a wide range of pH values 3-10. © 1993 John Wiley & Sons, Inc.
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    Removal of phenols from wastewater by soluble and immobilized tyrosinase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 854-858 
    Details
    ISSN: 0006-3592
    Keywords: phenol ; tyrosinase ; immobilization ; chitosan ; immobilized enzyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzymatic method for removal of phenols from industrial wastewater was investigated. Phenols in an aqueous solution were removed after treatment with mushroom tyrosinase. The reduction order of substituted phenols is catechol 〉 p-cresol 〉 p-chlorophenol 〉 phenol 〉 p-methoxyphenol. In the treatment of tyrosinase alone, no precipitate was formed but a color change from colorless to dark-brown was observed. The colored products were removed by chitin and chitosan which are available abundantly as shellfish waste. In addition, the reduction rate of phenols was observed to be accelerated in the presence of chitosan. Tyrosinase, immobilized by using amino groups in the enzyme on cation exchange resins, can be used repeatedly. By treatment with immobilized tyrosinase, 100% of phenol was removed after 2 h, and the activity was reduced very little even after 10 repeat treatments. © 1993 John Wiley & Sons, Inc.
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    Comparison of glucose fermentation by suspended and gel-entrapped yeast cells: An in vivo nuclear magnetic resonance study (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 647-653 
    Details
    ISSN: 0006-3592
    Keywords: yeast ; continuous-flow 31P NMR ; intracellular pH ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phosphorus-31 nuclear magnetic resonance (31P NMR) was used to compare the anaerobic metabolism of glucose by suspended and gel-entrapped Saccharomyces bayanus cells. The fermentation of glucose was carried out in a reaction system with continuous circulation through the NMR sample tube. The intracellular pH and the levels of some phosphorylated compounds were the levels of some phosphorylated compounds were noninvasively monitored by 31P NMR while glucose, fermentation products, and biomass were determined by analytic techniques comparisons showed that no significant differences are observed in the relative concentrations in the spectra, but distinct profiles for the variation of both intracellular and extracellular pH are found. The internal pH of immobilized cells is maintained at a constant value throughout the fermentation as opposed to freely suspended cells for which a steady decrease in the internal pH occurs. A faster and stronger acidification is also observed in the external medium of the assays with suspended cells. Furthermore, higher yields for ethanol and biomass production and lower yields of fermentation by-products are obtained with immobilized cells. It is concluded that the higher intracellular pH achieved in the presence of the gel matrix had a regulatory effect on the metabolism which favored the ethanol production pathway. © 1993 John Wiley & Sons, Inc.
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    Nystatin and killer toxin sensitivity of free and immobilizedSaccharomyces cerevisiae (1992)
    Springer
    World journal of microbiology and biotechnology 8 (1992), S. 192-195 
    Details
    ISSN: 1573-0972
    Keywords: Covalent linkage ; immobilization ; killer toxin ; nystatin ; Phospholipids ; Signal transduction ; sterols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The inhibitory effect of nystatin and killer toxin on the growth of free and covalently-immobilizedSaccharomyces cerevisiae cells was studied. The resistance of immobilized cells to both agents was accompanied by increased amounts of phospholipids and sterols. The possible relationship between these changes in the membrane composition and the transduction of a signal across the cytoplasmic membrane is discussed.
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    Surface immobilization of anchorage-dependent mammalian cells (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 697-706 
    Details
    ISSN: 0006-3592
    Keywords: anchorage-dependent mammalian cells ; immobilization ; fibers ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Anchorage-dependent HeLa cells were successfully cultured on two fibrous materials (A07 and R100) with porosities of 75-125 and 40 μm, void fractions of 92% and 81%, and fiber diameters of 7.6 and 10.2 μm, respectively, in 100-mL spinner flasks and 2-L stirred tank bioreactors. The matrix was formed into a fixed vertical spiral configuration. All cultures displayed rapid (≤2-3 h) attachment of inoculated cells (≥95%) to the matrix, uniform coverage of the immobilizing area with viable cells, and no significant amount of cell debris in the medium. Spinner flask cultures indicated that the denser material R100 showed better results in terms of final cell density. The growth of HeLa cells on material R100 in both culture systems was similar to that observed in tissue culture dishes (specific growth rate ∼0.03-0.04 h-1, maximum cell density of 8 × 106-9 × 106 cells · mL-1, and yields of 0.4 × 108 cells · mM-1 on glucose and 2 × 108-3 × 108 cells · mM-1 on glutamine). Scale-up of this culture technique in a 2-L bioreactor under perfusion with pH and dissolved oxygen (DO) control yielded cell densities of up to 1.6 × 106 cells · mL-1. Two other anchorage-dependent mammalian cells (ADC) known to be cultured with difficulty in roller bottles or with micro carriers were easily grown on material R100 in spinner flasks. The performance of this culture technique was compared to other ADC culture systems.
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    Inner mitochondrial membranes bound to concanavalin A-sepharose display succinate dehydrogenase, ATPase, and cytochrome oxidase activity (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 1080-1085 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; mitochondrial membranes ; cytochrome oxidase ; ATPase, concanavalin A-Sepharose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fraction (15-20% of the total protein) of a preparation of bovine submitochondrial particles (SMPs) binds to concanavalin A-sepharose. The bound membranes displayed succinate dehydrogenase, cytochrome oxidase, and ATPase activity, which, as in SMPs, were inhibited by malonate, cyanide, and oligomycin, respectively. These results indicate that the bound membranes are inner mitochondrial membranes and that they contain a glycoprotein which was recognized by concanavalin A. It was possible to repeatedly perform the three enzyme assays, one after the other, in the same gel with the bound membranes. Long-term stability tests (22 days) showed that cytochrome oxidase was much more stable in the membranes bound to the gel than in SMPs, while the ATPase activity decayed at a similar rate in the two conditions. Thus, inner mitochondrial membranes bound to ConA-Sepharose appear to be a potentially interesting model for the study of immobilized multienzymatic complexes.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260391103
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    Protein immobilization to alumina supports: I. Characterization of alumina-organophosphate ligand interactions and use in the attachment of papain (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1319-1327 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; chemical adsorption ; alumina ; phosphate ; papain ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The chemical adsorption of organic phosphate compounds to alumina has been used to create surface linkers for protein immobilization. A number of particulate alumina supports were screened for their physical properties and ability to bind organic phosphate compounds. Two aluminas, termed C1 and CPC, were selected based on their suitability for subsequent testing as protein immobilization supports. Papain was successfully immobilized to these supports when derivatized with phosphate compounds containing free terminal carboxyl groups. Protein binding was enhanced when support carboxyl groups were activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The level of papain immobilization was dependent upon the length of the linker used and the mass of protein exposed to the support. © 1992 John Wiley & Sons, Inc.
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    Optimization of accessible catalase activity in polyacrylamide gel-immobilized Saccharomyces cerevisiae (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 638-642 
    Details
    ISSN: 0006-3592
    Keywords: catalase ; Saccharomyces cerevisiae ; polyacrylamide gel ; immobilization ; permeabilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The permeabilization of Saccharomyces cerevisiae (baker's yeast), either before or after immobilization in polyacrylamide gel (PAG), has been examined as a means to increase the catalase activity of PAG-immobilized yeast cells. Prior permeabilization of the cells resulted in large losses of catalase activity during immobilization, but permeabilization after immobilization produced increases in the catalase activity of yeast/PAG particles. A dependence of the accessible catalase activity on the concentration of polyacrylamide in permeabilized yeast/PAG particles, and on the method of permeabilization of the immobilized cells, was observed. Optimal levels of stable catalase activity (1000-2000 IU/g PAG particles; ca. 5%-10% of total available activity) were obtained by immobilizing yeast cells (0.5 g wet cells/mL gel) in 10% (w/v) PAG, followed by permeabilization of the entrapped cells with either cetyltrimethylammonium bromide, Triton X-100 and one freeze-thaw, or five freeze-thaw cycles. © 1992 John Wiley & Sons, Inc.
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    Application of polystyrene-bound invertase to continuous sucrose hydrolysis on pilot scale (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 997-1003 
    Details
    ISSN: 0006-3592
    Keywords: invertase ; sucrose hydrolysis ; polystyrene resin ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Invertase from baker's yeast (Saccharomyces cerevisiae) covalently bound to a macroporous polystyrene anion-exchange resin via glutaraldehyde was applied to continuous sucrose hydrolysis in packed bed-reactors. The process was scaled up from 3-mL laboratory reactors via 0.3-L reactors to pilot-scale 50-L reactors without significant loss of efficiency. The described process allows the production of a wide spectrum of invert sugar syrups with high purity in continuous procedure. The 50-L reactor was used under process conditions 1 year without significant loss of productivity at a temperature of 40°C. A productivity of 760 g/h was obtained with 1 L invertase-polystyrene complex using a 2.5M sucrose solution as substrate. © 1992 John Wiley & Sons, Inc.
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    Activity and stability of an entrapped-cell system for the Δ1-dehydrogenation of steroids in organic media (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1123-1127 
    Details
    ISSN: 0006-3592
    Keywords: steriod Δ1-dehydrogenation ; immobilization ; Arthrobacter simplex ; polyurethane ; organic media ; thermostability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Whole Arthrobacter simplex cells entrapped in κ-carra-geenan or in two types of polyurethane foam, or adsorbed on silanized Celite, were tested for the Δ1-dehydrogenation of hydrocortisone and its derivatives in organic media. Catalytic activity and stability levels were evaluated for the immobilized cells in buffer with 2.5% (vol/vol) methanol, and in three buffer-saturated solvents (n-octan-1-ol, n-decan-1-ol, and chloroform). The addition of glutamate to the immobilization support stabilized the activity of the immobilized cells in the tested organic media. The system with polyurethane (HYPOL6100)-entrapped cells (with coimmobilized glutamate) in n-decan-1-ol provided the highest long-term activity levels. Several factors involved in the polyurethane-entrapment procedure were also studied. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260400918
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    Kinetic studies on urea hydrolysis by immobilized urease in a batch squeezer and flow reactor (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1203-1209 
    Details
    ISSN: 0006-3592
    Keywords: urease ; immobilization ; polyurethane foam ; biofilm reactor model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The immobilization of urease on the reticulated polyurethane foam, and the kinetic phenomenon of urea hydrolysis by the resulting immobilized urease in both batch squeezer and circulated flow reactors were studied. Urease was immobilized with bovine serum albumin and glutaraldehyde on polyurethane foam support of 7 to 15 μm thickness. The residual apparent activity of urease after immobilization was about 50%. The good hydrodynamic property and flexibility of polyurethane foam were retained in solution after immobilization. A modified biofilm reactor model was used to describe the kinetic phenomenon of urea hydrolysis in both batch squeezer and circulated flow reactors. The characteristic parameters of the reactor model for both bioreactors were obtained by combining the Rosenbrock optimization method, the Rungs-Kutta method, and the Newton-Raphson method. The best-fit results were in good agreement with the experimental data. This study suggests another application of polyurethane foam in enzyme immobilization and immobilized enzyme reactors, which offers potential for practical applications in various bioreactors. © 1992 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bit.260401010
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    Protein immobilization to alumina supports: II. Papain immobilization to alumina via organophosphate linkers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1328-1336 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; papain ; alumina ; kinetics ; fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Particulate aluminum oxides (alumina) were examined as supports for the immobilization of the proteolytic enzyme papain. Two alumina supports termed C1 and CPC were derivatized using organic phosphate linkers to create free carboxyl groups using a two-step process. Papain binding to these derivatized aluminas was performed using the water soluble carbodiimide 1-ethyl-3-(dimethylaminopropyl) carbodiimide. Reactions were optimal at 10 mM carbodiimide. The immobilized protein showed similar kinetic constants when compared to the solution protein. The pH dependence and thermal stability were essentially identical. The immobilized papain showed a blue shift in the intrinsic fluorescence emission maxima. Papain modified with the active site-specific fluorescent probe acrylodan showed overlapping emission maxima. These results are interpreted as retention of the hydrophobic environment of the active site with a perturbation in the structure of the rest of the protein caused by its association with the negatively charged surface. © 1992 John Wiley & Sons, Inc.
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    Continuous hydrolysis of olive oil by immobilized lipase in organic solvent (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 748-752 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; immobilization ; DEAE-sephadex ; organic solvent ; continuous hydrolysis reaction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipase (EC 3.1.1.3) from Candida rugosa was immobilized with DEAE-Sephadex A50, Sephadex G50, Sephadex LH-20, Amberlite IRA94, and Amberlite XAD-7. The enzye immobilized with DEAE-Sephadex A50 was found to be most effective for continuous hydrolysis of olive oil in isooctane. For the continuous reaction, 0.2 g of dry immobilized enzyme was swollen with predetermined amount of water, and packed in a glass column reactor. When the organic solvent (Isooctane) containing olive oil substrate was cocurrently fed with aqueous buffer, the two phases were evenly distributed throughout the packed bed without surfactant supplement or prior mixing of the two phases. A small amount of the surfactant (AOT) was used only in packing procedure, and no additional surfactant was necessary thereafter. Effects of initial water content of the swollen gel, buffer types, and strength were examined in the continuous reaction. Our results suggest that the operational half-life was affected by desorption of the bound enzyme. Under the conditions of 20% olive oil in isooctane and 25 mM triethanolamine buffer (pH 7.0), operational half life was 220 h at 30°C. The reactor was also operable with n-hexane, but the operational stability of the immobilized enzyme in n-hexane was only half of that in isooctane. Our results indicate that various enzyme carrier having hydrophilic or amphiphilic properties could be used for two-phase continuous reaction in packed-bed column, reactor without any surfactant supply or prior dispersion of the two immiscible phases. © 1992 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bit.260400615
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    Stimulative effect of non-parenchymal liver cells on ability of tyrosine aminotransferase induction in hepatocytes (1992)
    Springer
    Cytotechnology 10 (1992), S. 25-31 
    Details
    ISSN: 1573-0778
    Keywords: bioartificial liver ; calcium alginate ; hepatocytes ; immobilization ; non-parenchymal liver cell ; tyrosine aminotransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Hepatocytes and non-parenchymal liver cells were isolated from adult rat liver and co-cultured for 48 hours as a monolayer on polystyrene culture dishes. The ability of tyrosine aminotransferase (TAT) induction in hepatocytes was examined in the presence of dexamethasone and dibutyryl cAMP. Non-parenchymal cells greatly enhance the ability of TAT induction of hepatocytes. A soluble factor with molecular weight of more than 10,000 is responsible for this enhancement, because conditioned medium prepared from non-parenchymal cells is also stimulatory. Non-parenchymal cells restored the ability in hepatocytes damaged with the addition of D-galactosamine. Conditioned medium prepared from non-parenchymal cells treated with D-galactosamine had higher activity of enhancement than the medium from normal cells. The soluble factor might be released in response to some signal of injury. Hepatocytes and non-parenchymal cells were immobilized within Ca-alginate, and although immobilized hepatocytes rapidly lost the ability to induce TAT, hepatocytes co-immobilized with non-parenchymal cells maintained the ability during 4 days of culture. These results indicated that non-parenchymal liver cells, as well as hepatocytes, could be used to construct a bioartificial liver support system.
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    Production of monoclonal antibody using free-suspended and immobilized hybridoma cells: Effect of serum (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 821-830 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; immobilization ; serum ; flow cytometry ; antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of serum on cell growth and monoclonal antibody (MAb) productivity was studied in a repeated fedbatch mode using both free-suspended and immobilized S3H5/γ2bA2 hybridoma cells. In the suspension culture, serum influenced the cell growth rate but not the specific MAb productivity. The average specific growth rate of the suspension culture in medium containing 10% serum was approximately 0.99 ± 0.12 day-1 (±standard deviation), while that in medium containing 1% serum was approximately 0.73 ± 0.12 day-1. The specific MAb productivity was almost constant at 3.69 ± 0.57 μg/106 cells/day irrespective of serum concentration reached a maximum at ca. 1.8 × 106 cells/mL of medium in 10% serum medium, and the cell concentration was gradually reduced to 1%. The specific MAb productivity of the immobilized cells was more than three times higher than that of the free-suspended cells. The amount of serum in the medium did not influence the specific MAb production rate of the immobilized cells. The maintenance of high cell concentration and the enhanced specific MAb productivity of the immobilized cell culture resulted in a higher volumetric MAb productivity. In addition, MAb yield in the immobilized cell culture with medium containing 1% serum was 2.2 mg/mL of serum, which was approximately three times higher than that in the suspension culture.
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    Growth and immobilization of tripterygium wilfordii cultured cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1285-1291 
    Details
    ISSN: 0006-3592
    Keywords: Tripterygium Wilfordii ; plant cell culture ; suspension ; medium ; immobilization ; bioreactor culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The plant Tripterygium wilfordii produces di- and triterpenes of interest for male contraception and treatment of arthritis and skin disorders. Cell line TRP4a obtained form this plant in 1981 was reported to produce these valuable compounds at yields (∼0.04% of the biomass dry weight) higher than found in the plant (0.001%). In order to improve this production, studies were carried out to determine the feasibility of eliminating the troublesome component of coconut milk originally used to culture this cell line. A defined formulation suitable for growth ad maintenance has been developed. This medium consisted of Gamborg's PRL4 or B5 medium supplemented with 2 mg L-1 2,4-dichlorophenoxyacetic acid and 20 g L-1 sucrose. Furthermore, monitoring of carbohydrate uptake revealed that T. wilfordii cells, contrary to many plant cell species, did not hydrolyze sucrose extra-cellularly before uptake. Replacement of this disaccharide by glucose or fructose increased specific growth rate from 0.15 to 0.25 day-1. As tripdiolide is reported to be present in broth extract in significant amounts, plant cell immobilization technology offers a promising alternative to suspension cultures, especially in view to on line harvesting of the product. Surface immobilized T. wilfordii cell cultures were successfully carried out in 2-L bioreactors. Their biomass production and carbohydrate uptake were comparable to those observed for shake flask grown suspension cultures. Higher nitrate and ammonium uptake were found in immobilized cultures.
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    Analysis of mass transfer for immobilized cells in an extractive lactic acid fermentation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 544-550 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; extractive fermentation ; Lactobacillus delbrueckii ; k-carrageenan ; mass transfer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of immobilization in extractive lactic acid fermentation by Lactobacillus delbrueckii is preferred. In this article, the mathematical simulations to examine the influences of substrate and product transport were performed to assess the overall performance. The simulations showed that transport of the substrate in k-carrageenan beads was not a rate limiting factor. However, the model observed significant buildup of inhibitory product in large beads. The model was validated through comparisons with the experimental results. Finally, the model was used to predict the performance of the extractive fermentation under different operating strategies.
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    Methanol biosynthesis by covalently immobilized cells of Methylosinus trichosporium: Batch and continuous studies (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 551-556 
    Details
    ISSN: 0006-3592
    Keywords: Methylosinus trichosporium ; methanol biosynthesis ; immobilization ; batch and continuous studies ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The DEAE-cellulose linked cells of Methylosinus trichosporium displaying high specific methane mono-oxygenase activity (66 μmol methane oxidized/h mg cells) were used for methanol biosynthesis from biogas derived methane in a batch and a continuous cell reactor. The optimum cell-to-carrier ratio was determined to be 0.5 g cells/g dry weight cellulose. Batch experiments indicated that 100 mM phosphate ion concentration was necessary to inhibit further oxidation of methanol; excess oxygen supply favored methanol accumulation with an increase in methane conversion efficiency to 27%. A pulse of 40 mM sodium formate at the end of 6 h resulted in restoration of methanol accumulation by regenerating NADH2 required for the sustained activity of methane mono-oxygenase. Maximum methanol level of 50 μmol/mg cells was obtained in the batch reactor. In a standard 50-mL ultrafiltration continuous reactor, the covalently linked cells produced methanol at a continuous rate of 100 μmol/h for the first 10 h, after which the methanol accumulation rate fell low due to the depletion of NADH2. The methanol accumulation could be stimulated by supplying sodium formate (40 mM) in either 20 or 100 mM phosphate buffer. Maximum methanol accumulation rate of 267 μmol/h was obtained when 20 mM formate was supplied in the feed stream containing 100 mM phosphate ions, and this level of biosynthesis was maintained for over 72 h. The stoichiometric balance made at various points of formate addition indicated that the molar amount of methanol generated at steady state is dependent on the equimolar addition of sodium formate to the feed. The half-life t1/2 and thermal denaturation rate constant Kd were computed to be 108 h and 6.42 × 10-3 h-1, respectively.
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    High density cultivation of BSK cells on sintered alumina ceramic foam support (1991)
    Springer
    Cytotechnology 5 (1991), S. 233-241 
    Details
    ISSN: 1573-0778
    Keywords: high cell density ; ceramic ; BHK ; perfusion system ; immobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A perfusion system which utilizes a porous ceramic core has been tested for the cultivation of transformed BHK cells which produce human transferrin. A design is presented in which cells are immobilized within the porous ceramic particle and are fed by continuous perfusion of batch liquid medium. It was found that more than 5×109 BHK cells could be supported within the 40 mL ceramic matrix, a ten-fold increase in cell density per unit surface area over the standard roller bottle cultures or a five-fold increase in volumetric cell density over suspension cultures. The cell specific productivity of human transferrin was similar to that observed in suspension culture. The system offers the advantages of significant reduction in serum requirements and the potential for scale-up.
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    Characterization of the biochemical behavior of glucose oxidase entrapped in a polypyrrole film (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 854-858 
    Details
    ISSN: 0006-3592
    Keywords: Polypyrrole ; glucose oxidase ; immobilization ; autoinactivation ; thermodesactivation ; stability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article reports the characterization of the biochemical behavior of glucose oxidase entrapped in polypyrrole. The immobilization of glucose oxidase in a polypyrrole film was performed by entrapment during the electropolymerization of pyrrole at a platinum electrode poised at 0.65 V vs. SCE in aqueous solution in a one-compartment electrochemical cell. Thin films of polypyrrole (0.11 μm) were obtained and the entrapped enzyme obeyed Michaelis kinetics, indicating no diffusional constraints of the substrate. Our results indicate that the entrapped glucose oxidase is more resistant to denaturation conditions such as alkaline pH and temperature (50 and 60°C) than the soluble form of the enzyme. The autoinactivation constant for the entrapped enzyme was also determined in presence of 0.25M of glucose and was 6.19 × 10-4 min-1, i.e., corresponding to a half-life value of 20 h. The results reported here show clearly that polypyrrole matrix has a strong stabilizing effect on the stucture and on the activity of glucose oxidase.
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    Increased protein productivity from immobilized recombinant yeast (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 1029-1036 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; protein production ; continuous culture Saccharomyces cerevisiae ; plasmid stability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Saccharomyces cerevisiae strain Mc16/p520 has an unstable plasmid, p520, which directs production of a wheat α-amylase. The effects of immobilizing this microorganism on the plasmid stability and the specific productivity of the secreted α-amylase were investigated. Small gelatin beads were used as the support in both fluidized and packed bed configurations, and the yeast cells were attached by covalent cross-linking with glutaraldehyde. These data were then compared to those for nonimmobilized, suspension cells.Plasmid stability was increased for the immobilized cells during continuous culture at dilution rates both above and below washout. Continuous suspension cultures were not stable and rapidly lost the plasmid. Immobilization caused an increase in specific and volumetric productivity during continuous culture, with a packed bed design resulting in the highest specific productivity.
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    URL: http://dx.doi.org/10.1002/bit.260371107
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    Oxygen uptake by entrapped hybridoma cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 1050-1053 
    Details
    ISSN: 0006-3592
    Keywords: hybridomas ; immobilization ; oxygen ; respiration ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxygen consumption by hybridoma cells immobilized in 1- and 3.9-mm-diameter calcium alginate beads was measured. The entrapped cells consumed oxygen at about 10 μmol/min per 109 cells, regardless of the bead size and cell loading. In contrast, the same cells in suspension culture respire at specific rates of 3-8 μmol/min per 109 cells (depending on the cell density). The growth rate of the immobilized cells was significantly reduced, while specific antibody production was comparable to that of free cells.
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    URL: http://dx.doi.org/10.1002/bit.260371110
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    Lipase kinetics: Hydrolysis of triacetin by lipase from Candida cylindracea in a hollow-fiber membrane reactor (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 727-732 
    Details
    ISSN: 0006-3592
    Keywords: lipase kinetics ; Candida cylindracea ; hydrolysis of triacetin ; hollow-fiber membrane reactor ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aptitude of a hollow-fiber membrane reactor to determine lipase kinetics was investigated using the hydrolysis of triacetin catalyzed by lipase from Canadida cylindracea as a model system. The binding of the lipase to the membrane appears not to be very specific (surface adsorption), and probably its conformation is hardly altered by immobilization, resulting in an activity comparable to that of the enzyme in its native form. The reaction kinetics defined on the membrane surface area were found to obey Michaelis-Menten kinetics. The specific activity of the lipase in the membrane reactor was found to be significantly higher than in an emulsion reactor. The activity and stability of the enzyme immobilized on a hydrophilic membrane surface seem not to be influenced significantly by the choice of the membrane material. The hollow-fiber membrane reactor is a suitable tool to assess lipase kinetics in a fast and convenient way.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380706
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  • 95
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    Diffusion of lactose in k-carrageenan/locust bean gum gel beads with or without entrapped growing lactic acid bacteria (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1041-1049 
    Details
    ISSN: 0006-3592
    Keywords: diffusion ; lactose ; get matrix ; immobilization ; growing cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effective diffusion coefficients (De) of lactose in κ-carrageenan (2.75% wt/wt)/locust bean gum (0.25% wt/wt) (LBG) gel beads (1.5-2.0-mm diameter)with or without entrapped lactic acid bacteria (LAB) were determined at 40°C. The effects of lactose concentration, bacteria strain (Streptococcus salivarius subsp. thermophilus and Lactobacillus casei subsp. casei) and cell content at various steps of the fermentation process (after immobilization, pre-incubation of the beads and successive fermentations) were measured on De as a first step for process modelling. Results were obtained from transiend concentration changes n well-stirred lactose solutions in which the beads were suspended. A mathematical model of unsteady-state diffusion in a sphere was used, and De was obtained from the best fit of the experimental data. Diffusivity of lactose in cell-tree beads was significantly lower than in pure water mainly because of the obstruction effect of the polymer chains and the hydration region. Furthermore, effective diffusivity and equilibrium partition factor were independent of lactose concentration in the range from 12.5 to 50 g/L. No significant difference was found for De (effective diffusivity) and Kp (partition) coefficients between beads entrapping S. thermophilus (approximately 5 × 109 CFU/mL) and cell-free beads. On the other hand higher cell counts obtained with L. casei (close to 1.8 × 1011 CFU/mL) increased mass transfer resistance resulting in lower effective diffusivities and Kp. Finally, the effects of the type of bacteria and their distribution in the beads on the diffusivity were also discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380913
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  • 96
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    High solids fermentation of hydrolysates of wheat starch B in a continuous dynamic immobilized biocatalyst bioreactor (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 81-84 
    Details
    ISSN: 1476-5535
    Keywords: Ethanol fermentation ; Wheat starch ; Saccharomyces cerevisiae ; immobilization ; Continuous dynamic immobilized biocatalyst bioreactor ; Biocatalyst bioreactor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A simple and efficient method of conversion of wheat starch B to ethanol was investigated. Employing a two-stage enzymatic saccharification process, 95% of the wheat starch was converted to fermentable sugars in 40 h. From 140 g/l total sugars in the feed solution, 63.6 g/l ethanol was produced continuously with a residence time of 3.3 h in a continuous dynamic immobilized biocatalyst bioreactor by immobilized cells ofSaccharomyces cerevisiae. The advantages and the application of this bioreactor to continuous alcoholic fermentation of industrial substrates are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569698
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  • 97
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    Production of erythropoietin by BHK cells growing on the microcarriers trapped in alginate gel beads (1989)
    Springer
    Cytotechnology 2 (1989), S. 141-145 
    Details
    ISSN: 1573-0778
    Keywords: alginate ; erythropoietin ; high-density ; immobilization ; microcarrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Baby hamster kidney (BHK) cells engineered to produce recombinant human erythropoietin (EPO) were cultured at high density on microcarriers entrapped by calcium alginate gel particles. In this system, the BHK cells proliferated not only on the microcarriers but also in vacant spaces in the alginate gel particles. These spaces contributed greatly to high-density cultivation of the cells and a high productivity of EPO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386147
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  • 98
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    An immobilized hybridoma culture perfusion system for production of monoclonal antibodies (1988)
    Springer
    Cytotechnology 1 (1988), S. 331-337 
    Details
    ISSN: 1573-0778
    Keywords: hybridoma ; immobilization ; monoclonal antibodies ; perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A fixed bed perfusion system for hybridoma cell immobilization is presented. The system consists of a culturing vessel (300 ml total volume) in which polyurethane (PU) sponges in the form of small cubes of about 5 mm sides are packed. Cells are immobilized by physical entrapment in the foam matrix. By entrapment of the cells in the pores of the matrix high cell concentration can be maintained in a mechanically protected environment. Medium is continuously circulated by an airlift pump mounted in the cell-free chamber (700 ml total volume). Medium flow rate, feeding rate, dissolved oxygen, pH, nutrient uptake and waste product formation can be easily monitored and controlled. Steady state conditions are established with medium dilution rates of 1.0–1.5 reactor volume per day. The steady state is characterized by a constant cell density, constant culture volume and constant glucose and lactate levels. Cell-free supernatant is collected continuously in a cold room adjacent to the 37°C culture room. Monoclonal antibodies (MAb) are produced at a concentration of 150–200 μg/ml for several weeks. An important feature of the system is the capacity to maintain a population of cells after the growth phase in a non-proliferating state for extended time periods expressing high titers of MAb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365078
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  • 99
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    Losses and transformation of nitrogen during composting of poultry manure with different amendments: An incubation experiment
    Amsterdam : Elsevier
    Bioresource Technology 47 (1994), S. 265-273 
    Details
    ISSN: 0960-8524
    Keywords: Ammonia volatilization ; ammonification ; composting ; elemental sulphur ; immobilization ; poultry manure ; zeolite
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0960-8524(94)90190-2
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  • 100
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    Physiology of alginate-immobilized Chlorella
    Amsterdam : Elsevier
    Enzyme and Microbial Technology 7 (1985), S. 212-216 
    Details
    ISSN: 0141-0229
    Keywords: Algae ; Chlorella ; alginate entrapment ; immobilization ; physiology
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0141-0229(85)80004-1
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