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  • Biochemistry and Biotechnology  (670)
  • 1990-1994  (670)
  • 1994  (670)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 267-274 
    ISSN: 0006-3592
    Keywords: microbial souring ; sulfate reduction ; porous media ; kinetics ; stoichiometry ; transport phenomena ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An anaerobic upflow porous media biofilm reactor was designed to study the kinetics and stoichiometry of hydrogen sulfide production by the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans (ATCC 5575) as the first step for the modeling and control of formation souring (H2S) in oil field porous media. The reactor was a packed bed (50 × 5.5 cm) tubular reactor. Sea sand (140 to 375 μm) was used as the porous media. The initial indication of souring was the appearance of well-separated black spots (precipitates of iron sulfide) in the sand bed. The blackened zones expanded radially and upward through the column. New spots also appeared and expanded into the cone shapes. Lactate (substrate) was depleted and hydrogen sulfide appeared in the effluent.Analysis of the pseudo-steady state column shows that there were concentration gradients for lactate and hydrogen sulfide along the column. The results indicate that most of the lactate was consumed at the front part of the column. Measurements of SRB biomass on the solid phase (sand) and in the liquid phase indicate that the maximum concentration of SRB biomass resided at the front part of the column while the maximum in the liquid phase occurred further downstream. The stoichiometry regarding lactate consumption and hydrogen sulfide production observed in the porous media reactor was different from that in a chemostat. After analyzing the radial dispersion coefficient for the SRB in porous media and kinetics of microbial growth, it was deduced that transport phenomena dominate the souring process in our porous media reactor system. © 1994 John Wiley & Sons, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 309-313 
    ISSN: 0006-3592
    Keywords: Penicillin G ; phenylacetic acid ; separation process ; Amberlite LA-2 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The separation of penicillin G (Pen G) from phenylacetic acid (PAA) by use of a supported liquid membrane (SLM) system with Amberlite LA-2 dissolved in 1-decanol, supported on a microporous polypropylene membrane, was studied. The results show that the individual permeability of each component in mixture was lower than that in a single compartment system and, it suggests a strong transport competition between Pen G and PAA. The SLM system in this study proved to be a promising process for the selective separation of Pen G from PAA. The maximum separation factor was found to be 1.8 under a liquid membrane resistance controlled mechanism. © 1994 John Wiley & Sons, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 331-336 
    ISSN: 0006-3592
    Keywords: enzyme inactivation ; organic solvents ; urease ; interfacial area ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A liquid-liquid bubble column apparatus allows exposure of enzyme solutions to water-immiscible organic solvents with a known total interfacial area and welldefined time scales and flow. It allows clear distinction of the different classes of inactivation mechanism. With urease as a model enzyme, octan-2-one and butylbenzene act only through the effects of solvent molecules dissolved in the aqueous phase, giving first-order inactivation at 0.34 and 0.21 h-1, respectively. Hexane and tridecane act only through exposure to the interface. The amount of urease inactivated is proportional to the total area of interface exposed, rather than to elapsed time, and may be characterized by a rate of about 0.5 μkat m-2. This is consistent with the formation and (partial) inactivation of a complete adsorbed monolayer of protein. With butan-1-ol, both mechanisms contribute significantly to the observed inactivation. The presence of O2 increases the rate of interfacial inactivation, but not that by dissolved solvent. © 1994 John Wiley & Sons, Inc.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 349-356 
    ISSN: 0006-3592
    Keywords: immobilized metal ion affinity chmotagraphy ; baculovirus expression system ; infectious bursal disease virus ; protein purification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Over the past 10 years, the baculovirus-insect cell system has become a powerful and versatile tool for the expression of a variety of heterologous proteins. In order to simplify separation of a cloned protein from the baculovirus-insect expression system, we have cloned a gene encoding for the protein of interest, a structural protein (VP2) of a strain (E/DEL) of infectious bursal disease virus (IBDV), with a metal ion binding site (His)5 at its C-terminus. This chimeric protein (VP2H) has been expressed and one-step affinity purified with immobilized metal ions (Ni+2). With antigen capture-enzyme-linked immunosorbent assay (AC-ELISA), we determined that the conformation of this chimeric protein was no different from the recombinant wild-type VP2 protein. However, the two proteins (VP2 and VP2H) can be distinguished and resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and detected immunologically following Western blotting. © 1994 John Wiley & Sons, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 357-364 
    ISSN: 0006-3592
    Keywords: Thiobacillus ferrooxidans ; pyrite/arsenopyrite leaching ; Monod kinetics ; arsenic inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of dilution rate and feed solids concentration on the bacterial leaching of a pyrite/arsenopyrite ore concentrate was studied. A mathematical model was developed for the process based on the steady-state data collected over the range of dilution rates (20 to 110 h) and feed solids concentrations (6 to 18% w/v) studied. A modified Monod model with inhibition by arsenic was used to model bacterial ferrous ion oxidation rates. The model assumes that (i) pyrite and arsenopyrite leaching occurs solely by the action of ferric iron produced from the bacterial oxidation of ferrous iron and (ii) bacterial growth rates are proportional to ferrous ion oxidation rate. The equilibrium among the various ionic species present in the leach solution that are likely to have a significant effect on the bioleach process were included in the model. © 1994 John Wiley & Sons, Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 365-370 
    ISSN: 0006-3592
    Keywords: biocatalysis in organic media ; partion coefficients of substrate and product ; log P ; water activity ; mushroom tyrosinase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of solvent on the activity of mushroom tyrosinase toward three substrates was studied at a constant water activity of either 0.74 or 0.86. No simple correlation was observed between enzyme activity and log P, but partition coefficients of substrate (Ps) and product (Pp) gave systematic relations with enzyme activity. When initial reaction rates were considered, there was a bellshaped relationship between enzyme activity and Ps with an optimal Ps for each substrate. This can be explained by assuming that the solvent affected the enzyme activity primarily by affecting the substrate concentration in the aqueous layer around the catalyst where the enzymic reaction occurs. When long-term reaction rates were considered, a high Pp/Ps ratio was consistent with preservation of enzyme activity. © 1994 John Wiley & Sons, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 399-410 
    ISSN: 0006-3592
    Keywords: lac-based promoters ; Escherichia coli ; genetic control ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model that describes induction of protein synthesis from lac-based promoters has been developed and incorporated into the single-cell model of Escherichia coli with transcriptional and translational modifications. Unlike previous models of lac-based promoters, this model allows a priori prediction of the intracellular parameters controlling transcription from lac-based promoters with only the extracellular levels of substrate and inducer as inputs. Because of the structural detail of the model, it is possible to simulate different genetic constructions for comparison, such as Laclq strains versus wild-type cells, or including lacl on a multicopy plasmid. Expression from lac to tac promoters is predicted to yield 5% and 30% of the total cellular protein, respectively, with a pBR322-type plasmid. The model predicts the experimental observation that the Laclq strain is not as fully induced as the wild-type strains, even at higher inducer concentrations. Additionally, the model predicts the right order of magnitude of protein production from lac and tac promoters when mechanisms for attenuation of transcription at lower translational efficiency are considered. Finally, the model predicts that for high copy number systems ribosomes become limiting in the synthesis of plasmid-encoded proteins. © 1994 John Wiley & Sons, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 434-438 
    ISSN: 0006-3592
    Keywords: hybridoma ; continuous culture ; ammonia ; growth inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The nature and temporal development of ammonia inhbition were investigated in batch, fed-batch, and continuous cultures. Significant inhibition was observed when cells were inoculated in serum-containing or chemically defined medium containing more than 2 mM of ammonia. In contrast, no inhibition was observed at greater than 10 mM when the ammonia concentration was gradually increased over the span of a batch culture by feeding ammonium chloride. Strong growth inhibition was observed after each of five step changes (2.8 → 3.7 → 4.0 → 4.9 → 7.7 → 13.5 mM) in continuous culture. Following a period of adaptation at each higher value, the viable cell density stabilized at a new lower value. The lowering in viable cell density was caused by an increase in specific death rate and a decreased cell yield on glucose, glutamine, and oxygen. Increased ammonia concentration had little or no effect on the steady-state specific growth kinetics or specific antibody productivity. © 1994 John Wiley & Sons, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 439-445 
    ISSN: 0006-3592
    Keywords: extraction from whole broth ; aqueous two-phase partition ; separation ; cephalosporin C ; desacetyl cephalosporin C ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cephalosporin C was extracted from diluted or whole broth by PEG/salt aqueous two-phase systems. Parameters such as PEG molecular weight, salt type, pH, and salt concentration were investigated for finding a suitable extraction system. In PEG 600/ammonium sulfate or phosphate systems, Kc (partition coefficienct of cephalosporin C) was observed to be larger than 1, with Kd (partition coefficient of desacetyl cephalosporin C) being smaller than 1. The particular values of these coefficients would imply that the difficult separation of cephalosporin C and desacetyl cephalosporin C could possibly be achieved via the aqueous two-phase extraction. The addition of surfactants, water-miscible solvents, and neutral salts for enhancement of the separation efficiency was also investigated. The addition of surfactants to the system did not affect the separation efficiency substantially. Kc would increase whereas Kd decreased as a result of the addition of acetone, MeOH, EtOH, IPA, and n-BuOH. Meanwhile both Kc and Kd would decrease whenever neutral salts, NaCl, KCl, Kl, or KSCN, were added. The partitioning behavior of cephalosporin C and desacetyl cephalosporin C in filtered, whole, and different batches of broth was notably quite similar to that of diluted broth. The recovery yield of cephalosporin C in whole broth extraction was observed to be a function of centrifugal force used in phase separation. © 1994 John Wiley & Sons, Inc.
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  • 10
    ISSN: 0006-3592
    Keywords: liver cell culture ; bone marrow culture ; stromal cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stromal cell-associated liver cell and bone marrow (BM) culture on three-dimensiional nylon screen or polyglycolic acid (PGA) felt templates conveys certain functional advantages to the parenchyma of these tissues. Hepatic parenchymal cells (PC) manifest long-term (∼2 month) expression of liver-specific activities including cytochrome P450 enzyme activity and the synthesis of albumin, fibrinogen, transferrin, and other proteins. PC also undergo proliferation in association with stromal cells that were pre-established on these templates. PC mitoses are directly proportional to available space within the template for their expansion indication that geometric or sterotypic parameters influence the growth of these cells in vitro. BM cultured on a similar template exhibits long-term multilineage hematopoietic expression and limited expansion of progenitor cell numbers. Progenitor cell concentration within the cultures can be substantially enhanced if these cells are liberated from co-culture and reseeded onto a template containing fresh stromal cells. BM and liver cel cultures established on felt composed of bioresorbable PGA filaments was grafted into various sites in rats. Liver co-cultures generated sinusoids and other liver-like structures in situ; active hematopoietic blasts were observed at sites of BM co-culture grafts. Biodegradable polymer constructs may prove useful for certain clinical applications as vehicles for the delivery of tissues that were engineered in culture.
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