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  • Biochemistry and Biotechnology  (759)
  • 1995-1999
  • 1990-1994  (670)
  • 1970-1974  (89)
  • 1999
  • 1994  (670)
  • 1972  (89)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1990-1994  (670)
  • 1970-1974  (89)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Bacteria which attack petroleum hydrocarbons in a saline medium (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 319-330 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bacterial strains were isolated from California coastal areas which showed the ability to oxidize normal paraffins, iso-paraffins, and aromatic hydrocarbons in a synthetic seawater medium. The ability to utilize a particular hydrocarbon was established not only on the basis of visible bacterial growth but also through a chromatographic technique which was standardized and which could define the amount of each hydrocarbon consumed by the bacteria in a mixture. Some of the strains exhibited vigorous hydrocarbon oxidation when exposed to synthetic mixtures of hydrocarbons as well as crude oil. Under conditions of aeration and agitation, mixed cultures could destroy approximately 50% of a South Louisiana crude oil in a period of 48 hr.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140305
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  • 2
    Electronic Resource
    Electronic Resource
    Measurements on the interfacial areas of hydrocarbon in yeast fermentations and relationships to specific growth rates (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 345-360 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The transport of insoluble substrates such as hydrocarbons to microorganisms is often postulated to be dictated by the availability of the hydrocarbon surface area. Many publications, qualitative and quantitative, have appeared to substantiate this hypothesis. Experiments have been performed in our laboratory to assess the absolute values of the interfacial area of hexadecane as the carbon source for the growth of Candida intermedia. A sedimentometer, mounted directly in the fermentor, was used to measure the interfacial hydrocarbon area during active growth of this organism. The specific hydrocarbon interfacial area was found to be directly related to the impeller speed, hydrocarbon concentration and surfactant concentration in a 1-liter working volume, turbine-agitated fermentor. The specific growth rate was in turn found to be directly related to the specific hydrocarbon interfacial area. Lastly, cessation of logarithmic growth and onset of linear growth was found at all instances to be governed by the specific hydrocarbon surface area.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140307
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of growth rate and influent substrate concentration on effluent quality from chemostats containing bacteria in pure and mixed culture (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 391-410 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies were performed using pure cultures of A. acrogenes and E. coli and a heterogeneous microbial population growing in carbon-limited chemostats with glucose as the sole carbon and energy source. A two-level factorial experimental design was employed to test the hypothesis that the concentration of growth-limiting substrate in a chemostat is controlled by the growth rate alone and is independent of the concentration of substrate entering the reactor. The pure culture experiments showed that the conclusions depend upon the measurement employed for growth-limiting substrate. When the concentration of glucose was measured directly, the hypothesis was found to be true within the limits of the study (500-1500 mg/liter). However, if the chemical oxygen demand (COD) test was used as the measure of growth-limiting substrate the hypothesis was found to be false. When heterogeneous cultures were employed the hypothesis was false regardless of the technique used to measure the concentration of growth-limiting substrate. Nevertheless, it was possible to generate regression equations which described the interactions among influent COD, growth rate, and effluent COD with a high level of correlation.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140310
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal inactivation of immobilized enzymes in ideal continuous reactors (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 473-491 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The limitation of thermal inactivation on catalytic activity in continuous enzymatic reactions is considered. Where an enzyme is retained in a reaction environment which is open to mass transfer of reaction components, the effect of enzyme inactivation on reactant conversion depends on the order of the chemical reaction and the pattern of fluid flow through the reaction volume. Equations expressing conversion as a function of time for first-order inactivation are presented for Michaelis-Menten kinetics and the limiting fluid flow conditions of plug flow and complete back-mixing. Substrate protection or destruction of an enzyme is also considered and it is shown theoretically that the catalytic life of an enzyme may be optimized by the proper choice of fluid flow pattern.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140315
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  • 5
    Electronic Resource
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    Masthead (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140201
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  • 6
    Electronic Resource
    Electronic Resource
    Inactivation of immobilized catalase by hydrogen peroxide in continuous reactors (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 201-205 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown theoretically that in continuous reactions the rate of catalase inactivation by hydrogen peroxide depends on the type of reactor and the order of the chemical reaction.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140205
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  • 7
    Electronic Resource
    Electronic Resource
    Degradation and mineralization of petroleum by two bacteria isolated from coastal waters (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 297-308 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Within the framework of a study on the oil biodegradation potential of the sea the ability of a Flavobacterium sp. and Brevibacterium sp. to metabolize a paraffinic crude oil and a chemically defined hydrocarbon mixture was investigated. Major components of the crude oil were identified by combination gas chromatography and mass spectrometry. The rate and extent of total hydrocarbon biodegradation was measured. In addition, CO2 evolution from the crude oil was continuously monitored in a shaker-mounted gas train arrangement. Degradation started after a 2 to 4 day lag period, and reached its maximum within two weeks. At this time up to 60% of the crude oil and 75% of the model hydrocarbon mixture, each added at the level of 1 ml per 100 ml artificial sea water, were degraded. Mineralization(conversion to CO2) was slightly lower due to formation of products and bacterial cell material. n-Paraffins were preferentially degraded as compared to branched chain hydrocarbons. Biodegradation of n-paraffins in the range of C12 to C20 was simultaneous; no diauxie effects were observed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140303
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  • 8
    Electronic Resource
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    Flocculant production from kerosene (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 379-390 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cultivation of Corynebacterium hydrocarboclastus, which is capable of synthesizing an extracellular polymer and utilized hydrocarbons, has been reported. Growth studies in shake flasks and fermenters were made to obtain maximum polymer production. Polymer formation was found to be growth associated. The highest level of polymer accumulation was attained after 50-60 hr cultivation in the fermenter and it amounted to approximately 5.5-6 g/liter of fermentation broth. The medium contained initially 2% (v/v) kerosene as a carbon source. The maximum yield obtained corresponds to 37-40% (w/w) of kerosene supplied. At the same time the cell concentration was 10-13 g/liter which represents the yield of 67-87% (w/w). The rate of polymer production in the exponential phase was 0.25 g/liter hr and cell production rate was 0.27 g/liter hr. Sodium nitrate, 0.5%, and yeast extract, 0.3%, (w/w) were the best nigrogen sources for polymer formation. The highest level of polymer produced in broth was 6 g/liter.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140309
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  • 9
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    Large scale synthesis of dinucleoside monophosphates catalyzed by ribonuclease from Aspergillus clavatus (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 861-870 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A gram scale enzymatic synthesis of eight, dinucleoside monophosphates (ApC, ApU, CpC, CpU, GpC, GpU, UpC, and UpU) is described. The synthesis involves a reaction between the appropriate ribonucleoside-2′,3′-cyclie phosphates and cytidine or uridine in the presence of ribonuelease from Aspergillus clavatus at 30°C. The enzyme is removed from the reaction mixture by chromatography on Bio-Gel P-4, and the dinucleoside monophosphate is further purified by chromatography on a DEAE-Sephadex A-25, column.A procedure for the large scale preparation of the ribonuclease from Aspergillus clavatus is also described.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140602
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  • 10
    Electronic Resource
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    Conversion of deteriorated metal cutting fluids into protein (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 361-377 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Six soil isolates were grown on a petroleum sulfonate medium and analyzed chromatographically to determine their amino acid composition. The organisms were also examined to determine their growth rate in the petroleum medium, their per cent conversion of hydrocarbon to dry cell mass, their protein content, and their possible use as a food or food supplement. It was found that the isolates varied extensively as to their amino acid composition. Several of the isolates proved to convert the hydrocarbons to cell mass with relative ease. The proteins of four of the isolates appear to be suitable as a good food source, and the protein of one of the remaining isolates appears to be a very good food supplement.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140308
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  • 11
    Electronic Resource
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    Rubella virus replication at controlled dissolved oxygen tension (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 493-497 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140316
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  • 12
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    Glucose isomerase covalently bound to porous glass beadsPresented at 5th Great Lakes Regional American Chemical Society Meeting, Peoria, Illinois, June 10-11, 1971 (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 509-513 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140319
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  • 13
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    Growth models of cultures with two liquid phases. VII. Substrate dissolved in dispersed phase; effect of dispersed phase volume and temperature (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 571-586 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of dispersed phase volume and temperature on the batch growth of Candida lipolytica on gas oil are investigated. Growth parameters are presented for two sets of experiments. The shape of growth curves was basically similar to the system composed of n-hexadecane dissolved in dewaxed gas oil, in spite of the complex nature of the substance. All of the batch growth curves exhibited a linear growth region. The rate of linear growth and its length varied with change in dispersed phase volume. The effect of temperature on growth rate was investigated for temperatures ranging from 23°C to 34°C. The results show a smaller activation energy during linear growth than during the early stages of batch growth. These results are analyzed from the viewpoint of growth models presented previously. The results indicate that growth at drop surfaces is important and that segregation effects may be important.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140404
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  • 14
    Electronic Resource
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    Multiple junctions in the pipework of pilot plant fermenters (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 679-681 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140413
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  • 15
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    Dynamics and control of continuous microbial propagators to subject substrate inhibitionPresented in part at the 160th Annual Meeting of the American Chemical Society, September, 1970, Chicago and in part at the 63rd Annual Meeting of the American Institute of Chemical Engineers, November, 1970, Chicago. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 939-974 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inhibitory substrate levels are common in industrial fermentations and in biological waste-water treatment of many industrial wastes. Continuous microbial cultures are unstable to certain disturbances, such as shock loading by inhibitory substrates. Two feedback proportional control strategies are analyzed and compared for a simple model culture assumed represent able by the culture concentrations of biomass and a single rate-limiting and growth-limiting nutrient (substrate). One control strategy, the well known turbidostat, consists of adjusting culture holding time (e.g., by flow rate adjustment) in response to deviations in turbidity or some other measure of culture biomass concentration. The other control strategy is to adjust holding time in response to deviations in limiting nutrient concentrations in the culture. This second control strategy, termed the nutristat, can be superior to the turbidostat in many applications. The sign and magnitude of the dimensionless group {(X/YD)[dμ/dS]s}, is shown to be an important determinant, in the behavior of the open loop and the two closed loop processes. This characteristic group is positive when the specific growth rate is increased by increases in the nutrient concentration, zero when the growth rate is unaffected by the nutrient concentration, and negative in the presence of nutrient or substrate inhibition.The effects of process modifications and of modeling assumptions on the control of the process are discussed and more sophisticated control schemes are also proposed.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140606
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  • 16
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    Quantitative studies of the development of S. cerevisiae mitochondria (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 1007-1026 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The quantitative changes in mitochondria and cytochromes during transition of Saccharomyces cerevisiae from one steady state to another, while growing in continuous culture under controlled environmental conditions, were followed.No Mitochondria, or mitochondria like structures, were detectable in electron micrographs of permanganate-fixed anaerobic cells. Microaerobiosis (3μM dissolved oxygen) was sufficient to visualize mitochondrial profiles and induce cytochromes and their sections had a reduced number of mitochondrial profiles compared with cells grown in limiting glucose.In the presence of ergosterol and Tween 80 mitochondriogenesis, whether induced by aerobiosis or glucose limitation, involved enhanced definition of crystal and outer mitochondrial membranes and increased number of profiles. Where membrane formation was limited, by the absence of aerobiosis involved eytochrome induction and profile visualization, but limited profile Proliferation; the adapted cells consequently contained fewer, but more eytochrome-enriched, mitochondria than cells adapted in the presence of ergosterol and Tween 80.Increase in dissolved oxygen from 3μM to 52μM further enhanced membrane definition and increased the size, but not the number, of mitochondrial profiles.Evidence, obtained by measurement of eytochrome concentration per unit mitochondrial volume and per unit crystal area, support the concept that mitochondriogensis and cytochrome synthesis are not synchronized process and that cytochromes are added to or depleted from the mitochondrial cristae in response to culture conditions.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140609
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  • 17
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    Symbiotic growth of Acetobacter suboxydans and Saccharomyces carlsbergensis in a chemostat (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 75-92 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The bacterium Acetobacter suboyxdans and the yeast Saccharomyces carlsbergensis have been grown together on a synthetic medium in a chemostat. Mannitol, the only carbon source fed to the fermenter, is oxidized by the bacteria to fructose. The yeast, which cannot attack mannitol, breaks down the fructose nearly completely. Eight steady states and five transitory periods after changes in flow rate have been analyzed to study the kinetics of the mixed culture. Separate cell concentrations were determined by a modified Coulter counter apparatus. Both sugars were monitored. Both bacteria and yeast may be modeled using Monod's equation, the latter with some deviations. The yeast is unable to grow beyond the washout point of the bacteria, even though its maximum growth rate is much higher. The yield of both organisms decreases with increasing dilution rate, as does their average cell size. After step changes in dilution rate, repeated oscillations of both sugar and cell concentrations usually occur before steady-state conditions are reattained. They are generally in phase, with no definite sign of a lag. Oscillations of yeast and fructose concentrations are more pronounced. Periods average about 6 hr and are not correlated with fermentation conditions or equipment variables. Repeated oscillations are not found after step-downs in pure cultures of A. suboxydans, leading to the conclusion that the instability in mixed cultures may be caused by a feedback mechanism from the yeast to the bacteria.
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    URL: http://dx.doi.org/10.1002/bit.260140108
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  • 18
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    Continuous culture of Pseudomonas fluorescens with sodium maleate as a carbon sourcePresented in part before the Annual Meeting of the Division of Microbial Chemistry and Technology, American Chemical Society, Chicago, Illinois, September, 1970. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 123-147 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pseudomonas fluorescens (ATCC 11150) was grown in batch and continuous culture in minimal media with sodium maleate as growth-limiting sole organic carbon source. Growth was followed by turbidity and dry weight measurements. Gross composition of washed cells (relative amounts of protein, lipid, RNA, and DNA) and the distribution of amino acids in protein hydrolyses of the cells were determined for cells grown in continuous culture at various dilution rates. Extracellular concentrations of the original carbon source and a number of metabolites were monitored by a total carbon analysis, ion exchange chromatography, and ultraviolet-visible scans of cell-free supernatants and chromatographic fractions, thereof.Substrate inhibition by maleate was a major factor in the growth kinetics of both batch and continuous cultures. Excessive maleate concentration caused instability in continuous cultures. By appropriate operation, much higher specific growth rates (0.305/hr) could ultimately be achieved in continuous culture compared to batch culture (0.174/hr). Adaptation was responsible for only part of the differences between batch and continuous cultures; the differing distribution of metabolites were also major factors.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140111
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  • 19
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    Kinetic behavior of mixed populations of activated sludgePresented at the Symposium on Applications of Continuous Culture Theory to Biological Waste Water Treatment Processes, 162nd National American Chemical Society Meeting, Washington, D.C., September 13, 1971. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 179-199 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetic behavior of heterogeneous microbial populations of sewage origin was studied in a single-stage isothermal continuous flow completely mixed aeration tank. A series of experiments were carried out at various dilution rates using glucose as the growth limiting substrate. The steady-state behavior of the system was observed at each dilution rate and the results were found to fit fairly well with the steady-state equation bayed on the Monod model with an endogenous respiration term included, i.e., μ = μmS/(Ks + S) - Kd. The growth kinetics of cells harvested at steady state for each dilution rate were studied using batch experiments. The multiple response data of the system as functions of time were used to estimate the parameter values in the above kinetic model. It was found that values of the growth parameters changed significantly and systematically with cell population. For example, values of μm were high at high dilution rates and low at low dilution rates. It was also found that only those batch growth parameters from cells obtained at fairly high dilution rates are comparable with those estimated by the results of steady-state operations. The results of this investigation suggest that (1) different cell populations pre dominated at different steady-state dilution rates, with high dilution rates resulting in predominantly fast-growing organisms and low dilution rates resulting in predominantly slow-growing cells, and (2) risk exists in any randomly picked batch experiment to predict the steady-state behavior of the system when heterogeneous microbial populations must be used.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140204
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  • 20
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    Kinetic model identification in mixed populations using continuous culture data (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 207-231 
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    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetic behavior of heterogeneous microbial populations of sewage origin was studied in a single-stage, isothermal, continuous flow, completely mixed aeration tank. A series of experiments were carried out at various dilutions rates using glucose as the limiting substrate. The cell dry weight and substrate concentration in terms of chemical oxygen demand (COD) were continuously monitored. The results indicate that reproducible steady-state conditions can generally be obtained; however, multiple steady states were observed at dilution rates near washout. At low dilution rates (below about 0.1 hr-1) the contribution of microorganism decay became appreciable. Using the multiresponse data of cell dry weight and COD, the parameter values in various existing growth models were estimated. The analyses of variance and residuals revealed that models proposed by Moser, Monod, and Contois, each with a decay term added, were significantly better than the other models which were tested.
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    URL: http://dx.doi.org/10.1002/bit.260140206
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  • 21
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    Kinetic studies of the lactic acid fermentation in batch and continuous culturesPresented at 162nd National American Chemical Society meeting, Division of Microbial Chemistry and Technology, Washington, D.C., September 14, 1971. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 233-252 
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    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fermentation kinetics of the homofermentative organism Lactobacillus delbrueckii in a glucose-yeast extract medium is studied in both batch and continuous culture under conditions of controlled pH. From a graphical analysis of the batch data, a mathematical model of the process is derived which relates bacterial growth, glucose utilization, and lactic acid formation. The parameters in the model represent the activity of the organism and are a function of pH, having a maximum value at about 5.90. In a continuous stirred tank fermentor (CSTF), the effect of pH, feed concentration, and residence time is observed. The feed medium is a constant ratio of two parts glucose to one part yeast extract plus added mineral salts. An approximate prediction of the steady-state behavior of the CSTF can be made using a method based on the kinetic model derived for the batch case. In making step changes from one steady state to another, the transient response is observed. Using the kinetic model to simulate the transient period, the calculated behavior qualitatively predicts the observed response.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260140207
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  • 22
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    Effect of wall growth on scale-up problems and dynamic operating characteristics of the biological reactor (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 253-265 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: If inhibitory substrates are being utilized in a well-stirred biological reactor, microbiological growth on the walls of the reactor can create a scale-up problem. A simple model is proposed which shows that without such growth, of the three existing steady states only one is stable and nontrivial, but with wall growth the trivial, stable, steady state (washout) is impossible. In addition, wall growth reduces the region over which three steady states are feasible and reduces the minimum residence time for which there is only one steady state that corresponds to a high conversion. Thus, a laboratory process with a high surface area to volume ratio can give an over optimistic prediction of both necessary residence; time and stability of the full scale process unless wall growth is accounted for.
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    Biotechnology report: Solid state fermentationsPresented at the 1st International Mycological Congress, Exeter, England, September 7-16, 1971. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 517-532 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A unique method is described by which large yields of secondary metabolites arc produced on solid substrates. The process involves the use of moist substrates which are continuously agitated in appropriate fermentation equipment. The amount of agitation, aeration, and moisture can be varied. Extremely high yields of secondary metabolites such as ochratoxin and aflatoxin were obtained using Aspergillus and Penicillium species. The process prevents sporulation of the fungus and because of the nature of the solid substrate makes recovery of the product easier than in conventional liquid media. The substrates include rice, corn, wheat, and other cereals.
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    Measurement of yeast concentrations in liquid hydrocarbon fermentations: Influence of experimental conditions and statistical significance of the results obtained (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 609-615 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of the following factors on the measurement of yeast concentration in liquid hydrocarbon fermentations was studied: surfactant, type (Tween 20, Tween 80, and G 3300), yeast concentration (0.215 to 0.272 and 3.37 to 4.08 g/liter, as dry matter), oil concentration (8.32 and 61.6 g/liter), surfactant, concentration (0.515, 1.030, 1.545, and 2.060 g/liter), and time of contact of the surfactant with the oil-yeast-aqueous medium mixture (2 and 10 min). The statistical significance of the obtained results was determined.
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    External diffusional resistance in immobilized-enzyme catalysis (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 675-678 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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    Masthead (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260140501
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    The “rotary column” method for growth of large-scale quantities of cell monolayers (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 753-775 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method and an apparatus that reduce the heavy expenses involved in traditional methods for the large-scale monolayer production of primary and secondary, strain and line cells and of the biologicals derived therefrom are described. The method is based on the principle of gathering in a single unit a sheaf of columns by means of general manifolds fitted with cocks. The growth of cells on the glass walls is irrespective of the number, length, and diameter of the columns used. The apparatus, placed in a thermo-adjustable room and connected to adequate devices which allow it to rotate on its longitudinal axis and to be set in a vertical position, need not be dismounted nor transported since it can be connected by a number of tubes to the necessary services. Sterilization is carried out by flowing steam and fluids are poured in or drained off by vacuum or pressure. A microscope fitted to the bearing structure allows the operator to observe the cell monolayers and the cytopathic effect of viruses on the whole length of the outer columns. During the various working stages pH is under continuous control and automatically adjusted. The whole working cycle is extensively described (cleaning, sterilization, seeding, incubation, trypsinization of the monolayer, culture and harvesting of the virus) and results compared with those obtained by traditional methods.
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    Model for the growth of aerobic microorganisms under oxygen limiting conditions (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 787-798 
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    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple dynamic model is proposed which will allow fermenters to be run at throughputs which fully utilize the mass transfer capabilities of the fermenters while not decreasing the yield from the substrate. The model is compared with one previously proposed, which was originally formulated for double substrate limitation when both substrates were supplied in the feed. Computer solutions of the model are given which show the effects of the parameters used. Experimental results from growing Candida utilis on a high concentration of glucose were found to be similar to those predicted by the model.
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    The fermentation of L-sorbose by Gluconobacter melanogenus. II. Inducible formation of enzyme catalyzing conversion of L-sorbose to 2-keto-L-gulonic acid (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 811-818 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cell-free extracts of Gluconobacter melanogenus cells grown in L-sorbose-containing media contained an enzyme system capable of converting L-sorbose to 2-keto-L-gulonic acid while cells grown in glycerol media did not. This inducible enzyme was located in the participate fraction of the cells.
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    Kinetic studies of C. pyrenoidosa using 94% 13C CO2 (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 819-829 
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    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The alga Chlorella pyrenoidosa has been grown in mass quantities on 94 at. % 13CO2. The algal cells have been labeled to the 90 at. % 13C level. Neither inhibition nor a requirement for adaptation was encountered; changes in morphology were not evident. A statistically significant increase in mass of cells produced in the presence of 13CO2 was observed.
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    Induction of linear growth in candida utills by temporary cessation of growth (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 851-855 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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    Open tubular heterogeneous enzyme reactors: Preparation and kinetic behavior (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 885-914 
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    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Tubes with immobilized enzymes on the inner wall, called open tubular heterogeneous enzyme reactors, were prepared by binding enzymes either directly to the tube inside surface or to a layer of a porous matrix attached to the inner wall. Kinetic studies of the hydrolysis of N-benzoyl-L-arginine ethylester as a model reaction indicated that the reaction was kinetically controlled in reactors with surface bound trypsin and the kinetic parameters were evaluated by conventional methods. On the other hand, substrate diffusion in both the porous matrix and the bulk substrate solution strongly affected the rate of reaction in porous layer trypsin reactors. The highest overall rates of reaction were obtained when the reaction was bulk diffusion controlled and the measured rates were in agreement with those calculated from expressions derived from heat transfer theory. The design of reactors for the limiting cases of kinetic and bulk diffusion controlled reaction as well as a method for the determination of substrate diffusivity are outlined.
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    Proteases bound to diazotized sephadex anthranilate esters (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 1027-1030 
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    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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    The fermentation of L-sorbose by gluconobacter melanogenus. III. Investigation of the metabolic pathway from sorbose to 2-keto-L-gulonic acid (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 1035-1038 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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    An air-operated pinch valve for chemostat outlet flow control (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 1045-1046 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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    Kinetic analysis of microbial sulfate reduction by desulfovibrio desulfuricans in an anaerobic upflow porous media biofilm reactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 267-274 
    Details
    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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    Separation of penicillin G from phenylacetic acid in a supported liquid membrane system (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 309-313 
    Details
    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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    Inactivation of enzymes by organic solvents: New technique with well-defined interfacial area (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 331-336 
    Details
    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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    Purification of a recombinant protein produced in a baculovirus expression system by immobilized metal affinity chromatography (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 349-356 
    Details
    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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    A mathematical model for the bacterial oxidation of a sulfide ore concentrate (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 357-364 
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    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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    Partition coefficients of substrates and products and solvent selection for biocatalysis under nearly anhydrous conditions (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 365-370 
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    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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    Structured model of genetic control via the lac promoter in Escherichia coli (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 399-410 
    Details
    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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    Ammonia inhibition of hybridomas propagated in batch, fed-batch, and continuous culture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 434-438 
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    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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    Extraction of cephalosporin C from whole broth and separation of desacetyl cephalosporin C by aqueous two-phase partition (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 439-445 
    Details
    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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    Stereotypic culture systems for liver and bone marrow: Evidence for the development of functional tissue in vitro and following implantation in vivo (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 810-825 
    Details
    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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    Leuconostoc mesenteroides growth kinetics with application to bacterial profile modification (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 865-873 
    Details
    ISSN: 0006-3592
    Keywords: Leuconostoc mesenteroides ; dextran ; kinetics ; bacterial profile modification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bacterial profile modification (BPM) is being developed as an oil recovery technique that uses bacteria to selectively plug oil depleted zones within a reservoir to divert displacing fluids (typically water) into oil-rich zones. Leuconostoc mesenteroides, which produces dextran when supplied with sucrose, is a bacterium that is technically feasible for use in profile modification. However, the technique requires controlled bacterial growth to produce selective plugging.A kinetic model for the production of cells and polysaccharides has been developed for L. mesenteroides bacteria. This model, based on data from batch growth experiments, predicts saccharide utilization, cell generation, and dextran production. The underlying mechanism is the extracellular breakdown of sucrose into glucose and fructose and the subsequent production of polysaccharide (dextran). The monosaccharides are then available for growth. Accompanying sucrose consumption is the utilization of yeast extract. The cell requires a complex media that is provided by yeast extract as a source of vitamins and amino acids. Varying the concentration ratio of yeast extract to sucrose in the growth media provides a means of controlling the amount of polymer produced per cell. Consequently, in situ bacteria growth can be controlled by the manipulation of nutrient media composition, thereby providing the ability to create an overall strategy for the use of L. mesenteroides bacteria for profile modification.
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    Ammonia affects the glycosylation patterns of recombinant mouse placental lactogen-I by chinese hamster ovary cells in a pH-dependent manner (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 505-514 
    Details
    ISSN: 0006-3592
    Keywords: glycosylation ; recombinant protein expression ; CHO cells ; ammonia ; pH ; placental lactogen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The N-linked glycosylation of the recombinant protein mouse placental lactogen-I (mPL-I) expressed by Chinese hamster ovary (CHO) cells under nongrowth conditions was inhibited by increasing levels of ammonium chloride (3 and 9 mM) in a serum-free, protein expression medium. The effect of ammonia on glycosylation was dependent on the extracellular pH (pHe). In media containing 0 and 9 mM ammonium chloride, the percentage of the most heavily glycosylated forms of secreted mPL-I decreased from ca. 90% to ca. 25% at pHe 8.0, and from ca. 90% to ca. 65% at pHe 7.6, respectively. However, at pHe 7.2, the most heavily glycosylated forms of secreted mPL-I decreased from ca. 90% to ca. 80% in media containing 0 and 9 mM ammonium chloride, respectively. Inhibition of mPL-I glycosylation was found to correlate with the calculated concentrations of the ammonia species (NH3). Control experiments showed that the ammonia effect on mPL-I glycosylation could not be attributed to increased chloride concentration or osmolarity, or to extracellular events after secretion of the recombinant protein into the supernatant. Ammonium chloride, 9 mM, inhibited the expression rate of MPL-I by CHO cells at low pHe. © 1994 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bit.260430611
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    Sorption and precipitation of metals in activated sludge (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 874-880 
    Details
    ISSN: 0006-3592
    Keywords: sludge ; sorption ; precipitation ; metals ; adsorption ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A conceptual model describing the relative roles of sorption and precipitation processes for metals in solid-solution suspensions is presented. The model performance is demonstrated using experimental data on sorption and precipitation of metals in samples of activated sludge mixed liquor. Based on the experimental results presented here, it appears that, at total metal and mixed liquor suspended solids concentrations and pH values generally encountered in full-scale municipal (or combined municipal/industrial) activated sludge systems, metals are primarily removed by sorption processes.
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    URL: http://dx.doi.org/10.1002/bit.260430906
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    Mammalian cell damage in a novel membrane bioreactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 899-906 
    Details
    ISSN: 0006-3592
    Keywords: membrane bioreactor ; mammalian cell damage ; critical shear rate ; power dissipation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The experimental study has assessed a novel membrane bioreactor for mammalian cell culture. In the absence of a gas phase, the key features of cell damage associated with laminar and turbulent flow have been identified. The bioreactor employs a dimpled membrane in order to enhance transverse mixing in a narrow channel, but a fall in viable cell density has been observed at Reynolds numbers above Re = 83. In the laminar flow regime wall shear is the critical mechanism and an accurate calculation of shear rate in a complex channel has been achieved using the Reynolds analogy. Flow generating a wall shear rate in excess of 3000 s-1 has been shown to cause damage. Power dissipation measurements have been used to distinguish between laminar and turbulent flow and also to predict Kolmogorov eddy lengths. An additional turbulent bulk stress damage mechanism at higher Reynolds numbers (Re 〉 250) results in a very rapid fall in viable cell density.
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    Importance of solute partitioning in biphasic oxidation of benzyl alcohol by free and immobilized whole cells of pichia pastoris (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 918-924 
    Details
    ISSN: 0006-3592
    Keywords: biphasic oxidation ; immobilized whole cells ; organic solvent ; reagent partitioning ; benzyl alcohol ; Pichia pastoris ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using free and immobilized whole cells of Pichia pastoris, the biocatalytic oxidation of benzyl alcohol was investigated in different two-phase systems. This reaction was strongly influenced by both the substrate and product inhibitions, and the production rate of benzaldehyde in the aqueous system became maximum at the initial substrate concentration of ca. 29 g/L with the aldehyde formation less than 4 to 5 g/L even after a longer reaction period. The reaction rates in the two-liquid phase systems were predominantly determined by the partitioning behaviors of the substrate and product between the two phases rather than by enzyme deactivation by the organic solvents. In the two-liquid phase systems, consequently, the organic solvent acted as a reservior to reduce these inhibitory effects, and it was essential to select the organic solvent providing the optimal partitioning of the substrate into the aqueous phase as well as the preferential extraction of the product into the organic phase. The whole cells immobilized in a mixed matrix composed of silicone polymer [〉50% (v/v)] and Ca alginate gel (〈50%) worked well in the xylene and decane media, providing comparable activities with the free cells. The production rate of aldehyde was also influenced by the solute partitioning into the hydrophilic alginate phase where the cells existed. © 1994 John Wiley & Sons, Inc.
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    Biodegradation of pesticides in nonionic water-in-oil microemulsions of tween 85: Relationship between micelle structure and activity (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 946-959 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; phosphotriesterase ; reversed micelles ; microemulsions ; nonionic surfactants ; organophosphorus hydrolase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Water-in-oil microemulsion systems have been studied in recent years for a number of applications in protein separation and enzymology. Although it is well established that reversed micelle systems provide an excellent medium for nonaqueous biocatalytic studies, there is still much speculation as to the interaction of the enzyme with the surfactant interface. Polyoxyethylene sorbitan trioleate (Tween 85) is a nonionic surfactant which has some interesting properties for microemulsion formation and protein solubilization. In conjunction with a separate article describing the structural features of Tween 85 reversed micelles in hexane with isopropanol as a cosurfactant, this work describes the activity of an enzyme, organophosphorus hydrolase, for degrading organophosphorus pesticides in this microemulsion system. Ternary phase diagrams were constructed to outline the phase boundaries at different temperatures and isopropanol concentrations, which elucidate the role of the cosurfactant alcohol, as well as some features of micelle structure. Kinetic and stability studies with organophosphorus hydrolase show the effect of enzyme partitioning between the micelle surfactant layer and aqueous core. © 1994 John Wiley & Sons, Inc.
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    Pervaporative butanol fermentation by Clostridium acetobutylicum B18 (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 978-986 
    Details
    ISSN: 0006-3592
    Keywords: butanol ; fermentation ; Clostridium acetobutylicum ; acetone ; ethanol ; pervaporation ; fed batch ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extractive acetone-butanol-ethanol (ABE) fermentation was carried out successfully using pervaporation and a low-acid-producing Clostridium acetobutylicum B18. A pervaporation module with 0.17 m2 of surface area was made of silicone membrane of 240 μm thickness. Pervaporation experiments using make-up solutions showed that butanol and acetone fluxes increased linearly with their concentrations in the aqueous phase. Fickian diffusion coefficients were constants for fixed air flow rates, and increased at higher sweep air flow rates. During batch and fed-batch fermentations, pervaporation at an air flow rate of 8 L/min removed butanol and acetone efficiently. Butanol concentration was maintained below 4.5 g/L even though Clostridium acetobutylicum B18 produced butanol steadily. Pervaporation could not remove organic acids efficiently, but organic acids did not accumulate because strain B18 produced little organic acid and recycled added organic acids efficiently. With pervaporation, glucose consumption rate increased compared to without pervaporation, and up to 160 g/L of glucose was consumed during 80 h. Cell growth was not inhibited by possible salt accumulation or oxygen diffusion through the silicone tubing. The culture volume was maintained relatively constant during fed-batch operation because of an offsetting effect of water and product removal by pervaporation and addition of nutrient supplements. © 1994 John Wiley & Sons, Inc.
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    Cadmium removal in a biosorption column (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1010-1015 
    Details
    ISSN: 0006-3592
    Keywords: biosorption ; column sorption ; trickle column ; toxicity removal ; cadmium ; cadmium removal ; wastewater treatment ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New biosorbent material derived from a ubiquitous brown marine alga Ascophyllum nodosum has been examined in packed-bed flow-through sorption columns. It effectively removed 10 mg/L of cadmium down to 1.5 ppb levels in the effluent, representing 99.985% removal. The experimental methodology used was based on the early Bohart and Adams sorption model, resulting in quantitative determination of the characteristic process parameters which can be used for performance comparison and process design. An average metal loading of the biosorbent (N0) determined was 30 mg Cd/g, corresponding closely to that observed for the batch equilibrium metal concentration of 10 mg Cd/L. The critical bed depth (Dmin) for the potable water effluent quality standard (0.005 mgg Cd/L) varied with the column feed flow rate (2.4 to 9.6 L/h · cm2) from 20 to 50 cm. The sorption column mass transfer and dispersion coefficients were determined, which are also required for solving the sorption model equations. © 1994 John Wiley & Sons, Inc.
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    Cybernetic model for synthesis of poly-β-hydroxybutyric acid in Alcaligenes eutrophus (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1043-1051 
    Details
    ISSN: 0006-3592
    Keywords: cybernetic model ; poly-β-hydroxybutyric acid ; Alcaligenes eutrophus ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The pathway of poly-β-hydroxybutyric acid (PHB) exhibits a mode of transcriptional control induced by environmental stress. A new cybernetic model for coordinated regulation of stress-induced metabolism was developed to predict the growth and the synthesis of PHB in Alcaligenes eutrophus. A plausible objective for this control is optimization of acetyl-CoA utilization so that the cells have a high degree of flexibility in their catabolism. The state equation for key protein synthesis was assumed to have a dependence on the nonlinear control variable. The proposed model can demonstrate the mixed-growth-associated synythesis of PHB. Reported unstructured models were compared statistically with the result of the simulation derived from the proposed model using the experimental data of this study and the literature. The proposed model appeared to provide an excellent description for the overall fermentation range. © 1994 John Wiley & Sons, Inc.
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    Overproduction of glycogen in Escherichia coli blocked in the acetate pathway improves cell growth (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 132-139 
    Details
    ISSN: 0006-3592
    Keywords: glycogen ; Escherichia coli ; cell growth ; acetate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Excessive production of acetate is a problem frequently encountered in aerobic high-cell-density fermentations of Escherichia coli. Here, we have examined genetic alterations resulting in glycogen overproduction as a possible means to direct the flux of carbon away from the acetate pool. Glycogen overaccumulation was achieved either by using a regulatory glgQ mutation or by transforming cells with a plasmid containing the glycogen biosynthesis genes glgC (encoding ADPG pyrophosphorylase) and glgA (encoding glycogen synthase) under their native promoter. Both strategies resulted in an approximately five-fold increase in glycogen levels but had no significant effect on acetate excretion. The glgC and glgA genes were then placed under the control of the isopropyl---D-thiogalactopyranoside (IPTG) inducible tac promoter, and this construct was used to stimulate glycogen production in a mutant defective in acetate biosynthesis due to deletion of the ack (acetate kinase) and pta (phosphotransacetylase) genes. If glycogen overproduction in the ack pta strain was induced during the late log phase, biomass production increased by 15 to 20% relative to uninduced controls. Glycogen overaccumulation had a significant influence on carbon partitioning: The output of carbon dioxide peaked earlier than in the control strain, and the levels of an unusual fermentation byproduct, pyruvate, were reduced. Exogenous pyruvate was metabolized more rapidly, suggesting higher activity of gluconeogenesis or the tricarboxylic acid (TCA) cycle as a result of glycogen overproduction. Potential mechanisms of the observed metabolic alterations are discussed. Our results suggest that ack pta mutants over producing glycogen may be a suitable starting point for constructing E. coli strains with improved characteristics in high-cell-density fermentations. © 1994 John Wiley & Sons, Inc.
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    Genetically engineered charge modifications to enhance protein separation in aqueous two-phase systems: Electrochemical partitioning (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 147-153 
    Details
    ISSN: 0006-3592
    Keywords: aqueous two-phase systems ; β-galactosidase ; T4 lysozyme ; partitioning ; charge modifications ; genetic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have examined the effect of genetically engineered charge modifications on the partitioning behavior of proteins in dextran/polyethylene glycol two-phase systems containing potassium phosphate. By genetically altering a protein's charge, the role of charge on partitioning can be assessed directly without the need to modify the phase system. The charge modifications used are of two types: Charged tails of polyaspartic acid fused to β-galactosidase and charge-change point mutations of T4 lysozyme which replace positive lysine residues with negative glutamic acids. The partition coefficient Kp for these proteins was related to measured interfacial potential differences Δφ using the simple thermodynamic model, In Kp = In Ko + (F/RT)Zp δφ. The protein net charge Zp was determined using the Henderson-Hasselbalch relationship with modifications based on experimentally determined titration and isoelectric point data. It was found that when the electropartitioning term Zp δφ was varied by changing the pH, the partitioning of T4 lysozyme was quantitatively described by the thermodynamic model. The β-galactosidase fusions displayed qualitative agreement, and although less than predicted, the partitioning increased more than two orders of magnitude for the pH range examined. Changes in the partitioning of lysozyme due to the various mutations agreed qualitatively with the thermodynamic model, but with a smaller than expected dependence on the estimated charge differences. The β-galactosidase fusions, on the other hand, did not display a consistent charge based trend, which is likely due either to the enzyme's large size and complexity or to nonelectrostatic contributions from the tails. The lack of quantitative fit with the model described above suggests that the assumptions made in developing this model are oversimplified. © 1994 John Wiley & Sons, Inc.
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    Heterogeneity of biofilms in rotating annular reactors: Occurrence, structure, and consequences (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 194-204 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; biofilm reactors ; structure ; heterogeneity ; kinetics ; modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rotating annular reactor (Roto Torque) was used for qualitative and quantitative studied on biofilm heterogeneity. In contrast to the classic image of biofilms as smooth, homogeneous layers of biomass on a substratum, studies using various pure and mixed cultures consistently revealed more-dimensional structures that resembled dunes and ridges, among others. These heterogeneities were categorized and their underlying causes analyzed. Contrary to expectations, motility of the microorganisms not a decisive factor in determining biofilm homogeneity. Small Variations in substratum geometry homogeneity. Small variations in substratum geometry and flow patterns were clearly reflected in the biofilm pattern. Nonhomogeneous flow and shear patterns in the reactor, together with inadequate mixing resulted in significant, position-dependent differences in surface growth. It was therefore not possible to take representative samples of the attached biomass. Like many other types of reactors, the Roto Torque reactor is valuable for qualitative and morphological biofilm experiments but less suitable for quantitative physiological and kinetics studies using attached microorganisms. © 1994 John Wiley & Sons, Inc.
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    Adsorption of BSA on strongly basic chitosan: Equilibria (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1087-1093 
    Details
    ISSN: 0006-3592
    Keywords: adsorption ; ion exchange ; chitosan ; equilibrium ; BSA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equilibrium isotherms for adsorption of bovine serum albumin (BSA) on a new adsorbent, a strongly basic crosslinked chitosan (Chitopearl 2503), which is hard and is not compressed by pressure in a column, have been presented and compared with diethylaminoethyl (DEAE) Sepharose Fast Flow (hard gel). In Chitopearl 2503, when only buffer existed in the BSA solution, the isotherm was not affected by the initial concentration of BSA but it was affected by pH considerably. The isotherm was favorable when pH ≥ pl (≅ 4.8). When NaCl existed in the BSA solution, the amount of BSA absorbed on the resin decreased with increasing concentration of NaCl. When the concentration of NaCl was 200 mol/m3, the resin did not adsorb BSA at all. The equilibrium data were correlated by the Langmuir equation reasonably well. The BSA may be adsorbed mainly by electrostatic attraction between negatively charged BSA and positively charged quanternary ammonium groups at pH 〉 pl and by protonation reaction of the primary ammonium groups by weak acid groups of BSA at pH = pl. These are confirmed by measuring the amount of inorganic ion exchanged for BSA. In DEAE Sepharose Fast Flow, the isotherm was favorable when pH 〉 pl but unfavorable ar pH = pl. The saturation capacity of BSA on Chitopearl 2503 is about 1.3 to 2.2 times larger than that on DEAE Sepharose Fast Flow. © 1994 John Wiley & Sons, Inc.
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    Synthesis of aspartame precursor with an immobilized thermolysin in tert-amyl alcohol (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1118-1123 
    Details
    ISSN: 0006-3592
    Keywords: enzymatic synthesis ; peptide synthesis ; thermolysin ; immobilized enzyme ; aspartame precursor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: N-(Benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester (Z-AspPheOMe), a precursor of the synthetic sweetner asparatame, was synthesized from N-(benzyloxycarbolyl)-L-aspartic acid (Z-Asp) and L-phenylalanine methyl ester (PheOMe) with an immobilized thermolysin in various organic solvents. We found that in tert-amyl alcohol containing a small amount of water the immobilized enzyme showed a high activity comparble to that in ethyl acetate with quite a high stability. The immobilized enzyme was fully stable up to 70°C in tert-amyl alcohol in the absence of the subatrate, and up to 50°C in the presence of the substrate. The high stability in the presence of the substrate was found due to the fact that the release of calcium ions, the stabilizing factor of thermolysin, is suppressed.The substrate concentration dependence of the initial synthetic rate with the immobilized enzyme was quite different from that with the free enzyme in the biphasic system, in contrast to that in ethyl acetate. Finally, Z-AspPheOMe was continuously synthesized in a column reactor using 200 mM PheOMe and 120 mM Z-Asp as the substrate for over 300 h at 45°C and a space velocity of 1 h-1 without any loss of acivity. © 1994 John Wiley & Sons, Inc.
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    Protein fractionation using fast flow immobilized metal chelate affinity membranes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 21-36 
    Details
    ISSN: 0006-3592
    Keywords: affinity sorption ; microporous membrane ; metal chelate ; protein fractionation ; radial dispersion model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new group-specific affinity membrane using metal chelates as ligands and inorganic glass hollow fiber microfiltration membranes as support matrices is developed and tested. The study focused on developing the optimum activation and coupling procedures to bind the chelating agent (iminodiacetic acid, IDA) to the surface of the microporous glass hollow fiber membrane and testing the resultant affinity membrane. Starting with three different glass surfaces, five modification reactions were evaluated. All the modified “active surfaces” were first tested for their protein adsorptive properties in batch mode with suspended microporous glass grains using model proteins with known binding characteristics with Cu-IDA systems. The metal loading capacities of the surfaces exhibiting favorable fractionation were then measured by atomic absorption spectroscopy.The results were compared with the results obtained with a commercial material used in immobilized metal affinity column chromatography. The protein binding characteristics of the hollow fiber affinity membranes were also evaluated under conditions of convective flow. This was performed by flowing single solute protein solutions through the microporous membrane at different flow rates. These results were then used to estimate the optimum loading and elution times for the process. A mathematical model incorporating radial diffusion was solved using a finite difference discretization method. Comparison between model predictions and experimental results was performed for four different proteins at one flow rate. These results suggested that the kinetics of adsorption was concentration dependent. Finally, the hollow fiber affinity membranes were challenged with two component mixtures to test their ability to fractionate mixed protein solutions. Efficient separation and good purity were obtained.The results presented here represent the development of a new fast flow affinity membrane process-immobilized metal affinity membranes (IMAM). © 1994 John Wiley & Sons, Inc.
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    Rapid renaturation of denatured and aggregated proteins using liquid paraffin as a pseudolipid bilayer membrane (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 57-63 
    Details
    ISSN: 0006-3592
    Keywords: protein renaturation ; liquid paraffin ; BSA ; ribonuclease ; myoglobin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A means of rapidly renaturing denatured protein was devised and evaluated. Three liquids were laminarly layered in a centrifuge tube, in which two solutions sandwiched liquid paraffin so as to form a pseudolipid bilayer. Denatured and aggregted protein placed on the upper surface of liquid paraffin was renatured as it passed through liquid-paraffin layer into the renaturation buffer during the centrifugation. The aggregated and denatured protein selectively passed through the liquid-paraffin layer, whereas other solutions, such as chaotropic agents or organic solvent, could not. This means that a rapid dilution condition favorable for protein renaturation was realized in a small scale. Aggregated and denatured BSA and ribonuclease A were renatured and resolubilized as they passed through the liquid-paraffin layer into an appropriate renaturation buffer solution. This method was also applied to the rapid heme reconstitution of myoglobin from Feprotoporphyrin IX to Zn-protoporphyrin IX. © 1994 John Wiley & Sons, Inc.
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    The influence of polyalcohols and carbohydrates on the thermostability of α-amylase (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 107-114 
    Details
    ISSN: 0006-3592
    Keywords: polyols and carbohydrates ; protein thermostability ; heat inactivation kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of polyhydric alcohols and carbohydrates on the thermostability, i.e., the heat inactivation kinetics, of Bacillus licheniformis α-amylase was studied in the temperature range 96° to 130°C. High concentrations (from 9 to 60 weight percent) of glycerol, sorbitol, mannitol, sucrose, or starch can markedly decrease the inactivation rate constant, k, and in the studied cases, this stabilizing effect grows stronger with increasing additive concentration. Statements about stabilization should, however, be specified carefully with respect to temperature, because EA is mostly altered likewise. For dissolved enzyme EA was almost always decreased in the presence of polyol or carbohydrate, whereas for immobilized enzyme it was augmented in each studied instance. The inactivation of dissolved enzyme can, in all the studied cases, be adequately described as a firstorder process. Immobilized enzyme, however, shows biphasic then first-order inactivation kinetics, depending on the additive concentration and temperature. © 1994 John Wiley & Sons, Inc.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440801
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    Solids retention time in spherical biofilms in a biofilm airlift suspension reactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 867-879 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; microbeads ; solids retention time ; airlift reactor ; particulates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fluorescent microparticles were used as tracer beads to measure the dynamics of solids in spherical biofilms in a biofilm airlift suspension reactor. Attachment to, release from, and penetration into the biofilms of the tracer beads were measured. The coverage of the biofilm surface was low and the steady state particle concentration on the surface was dependent on the biofilm surface characteristics. The measured attachment rate constant was identical in both experiments and appeared to be determined by the hydrodynamic conditions in the turbulent reactor. The attachment rate was much faster than the release rate of the tracer beads and, therefore, the solidsretention time in the biofilm particle is not due to a simple reversible adsorption-desorption process. The heterogeneity of the distribution oftracer beads on different sectors on the biofilm surface decreased duringthe attachment period. Due to random detachment processes the heterogeneity of the tracer bead distribution increased during the release periodThe tracer beads quickly penetrated into the biofilm and became distributed throughout the active layer of the biofilm. The observed penetration into biofilms, the nonuniform distribution on the biofilm surface, and the fast uptake and slow release of tracer beads cannot be described by a simple model based on a reversible adsorption-desorption mechanism, nor withexisting biofilm models. These biofilm models, which balance growth and advection assuming a uniform biofilm with a homogeneous surface, are inadequate for the description of the observed solids retention time in biofilms. Therefore, a new concept of biofilm dynamics is proposed, in which formation of cracks and fissures, which are rapidly filled with growing biomass, combined with nonuniform local detachment, explains the observed fast penetration into the biofilm of tracer beads, the long residence time, and the nonuniform distibution of fluorescent microparticles. © 1994 John Wiley & Sons, Inc.
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    Improved taxol yield by aromatic carboxylic acid and amino acid feeding to cell cultures of taxus cuspidata (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 967-971 
    Details
    ISSN: 0006-3592
    Keywords: taxol production ; Taxus cuspidata ; cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cell culture of Taxus cuspidata represents an alternative to whole plant extraction as a source of taxol and related taxanes. Feeding phenylalanine to callus cultures was previously shown to result in increased taxol yields, probably due to the involvement of this amino acid as a precursor for the N-benzoylphenylisoserine side chain of taxol. Inthis study, we have examined the effect of various concentrations of phenylalanine, benzoic acid, N-benzoylglycine, serine, glycine, alanine, and 3-amino-3-phenyl-propionic acid on taxol accumulation in 2-year-old cell suspensions of Taxus cuspidata, cell line FCL1F, and in developing callus cultures of T. cuspidata. All compounds tested were included in media at stationary phase (suspensions) or after the period of fastest growth (calli). Alanine and 3-amino-3-phenyl-propionicacid were tested only in callus cultures and did not affect taxol accumulation. Significant increases or trends toward increases in taxol accumulationin callus and suspensions were observed in the presence of phenylalanine, benzoic acid, N-benzoylglycine, serine, and glycine. The greatest increases in taxol accumulation were observed in the presence of various concentrations of phenylalanine (1 mM for callus; 0.05, 0.1, and 0.2 mM for suspensions) and benzoic acid (0.2 and 1 mM for callus and 0.05, 0.1, and 0.2 mM for suspensions). Increases in taxol yields of cell suspensions in the presence of the most effective precursors brought taxol amounts at stationary phase from 2 μg · g-1 to approximately 10 μg . g-1 of the extracted dry weight. The results are discussed in termsof possible implications to taxol biosynthesis and in terms of practical applications to large-scale cell culture systems for the production ofthis drug. © 1994 John Wiley & Sons, Inc.
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    Kinetic modeling of interesterification reactions catalyzed by immobilized lipase (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 171-182 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; hydrophobic support ; interesterification ; olive oil ; butterfat ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetic data for lipase-catalyzed interesterification reactions between free fatty acids and triglycerides were collected and the dynamics of the interesterification reactions were successfully modeled using tow rate experssions requiring a total of five adjustable parameters. One rate expression describes the disappearance of the free fatty acid (octanoic or linolenic acid), and the second describes the rate of release of fatty acid residues from the triglycerides (olive oil or milkfat). This model is able to account for the effects of the concentration of all chemical species participating in interesterification throughout the entire reaction. When the data for both milkfat and olive oil were subjected to nonlinear regression analyses using the same mathematical model, the parameter estimates for both systems were comparable. In addition to reproducing the tendencies observed experimentally, simulations of the interesterification system under a variety of initial conditions provided insight into the effects of several reaction variables which could not be examined experimentally. Among the most significant findings of the simulation work are (1) there is a limit beyond which increasing the initial concentration of water produces no further increase in the initial rate of the interesterification reaction; (2) an increase in the initial concentration of lower glycerides produces a concomitant increase in the rate of the interesterification reaction; (3) the free fatty acids inhibit the rate of hydrolysis of the fatty acid residues of the triglycerides; (4) there is a limit beyond which increasing the initial concentration of triglycerides produces no significant increase in the rate of either the hydrolysis reaction or the interesterification reaction. © 1994 John Wiley & Sons, Inc.
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    EPR characterizations of α-chymotrypsin active site dynamics in reversed micelles at enhanced gas pressures and after subjection to clathrate formation conditions (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 215-224 
    Details
    ISSN: 0006-3592
    Keywords: EPR ; α-chymotrypsin ; reversed micelle ; clathrate hydrate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Electron paramagnetic resonance spectroscopy is used to characterize the active site dynamics of α-chymotrypsin solubilized in reversed micelles. Of particular interest is the behavior of the enzyme when the micellar system is subjected to enhanced gas pressures and low temperatures. At specific thermodynamic conditions, clathrate hydrates from from the intramicellar water, reducing the micelle size and water content. Also, beyond a critical pressure, micellar instbility results. The EPR spectra under these conditions indicate that the rotational correlation times increase appreciably only when the water-to-surfactant molar ratio, W0, is reduced to values lower than 10. The EPR characterization also reveals a remarkable resilience of the enzyme when subjected to pressure-induced changes; when returned to ambient conditions, activity and active site dynamics are fully restored. © 1994 John Wiley & Sons, Inc.
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    Immobilization of a proteinase from the extremely thermophilic organism Thermus Rt41A (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 225-231 
    Details
    ISSN: 0006-3592
    Keywords: Thermus ; proteinase ; enzyme immobilization ; enzyme hermostability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An extracellular proteinase from Thermus strain Rt41A was immobilized to controlled pore glass (CPG) beads. The properties of the free and CPG-immobilized enzymes were compared using both a large (azocasein) and a small (peptidase) substrate. The specific activity of the immobilized proteinase was 5284 azoU/mg with azocasein and 144 sucU/mg for SucAAPFpNA. The percentage recovery of enzyme activity was unaffected by pore size when it was immobilized at a fixed level of activity/g of beads, whereas it increased with increasing pore size when added at a fixed level/m2 of support. Saturation of the CPG beads was observed at 540 azoU/m2 of 105-nm beads. Lower levels (50 azoU/m2 of 50-nm beads) were used in characterization experiments. The pH optimum of the immobilized Rt41A proteinase was 8.0 for azocasein and 9.5 for SucAAPFpNA, compared with the free proteinase which was 10.5 for both substrates. The immobilized enzyme retained 65% of its maximum activity against azocasein at pH 12, whereas the free proteinase retained less than 10% under the same conditions. Stability at 80°C increased on immobilization at all pH values between 5 and 11, the greatest increase in half-life being approximately 12-fold at pH 7.0. Temperature-activity profiles for both the free and immobilized enzymes were similar for both substrates. The stability of the immobilized proteinase, however, was higher than that of the free enzyme in the absence and presence of CaCl2. Overall, the results show that low levels of calcium (10 μM) protect against thermal denaturation, but that high calcium or immobilization are required to protect against autolysis. © 1994 John Wiley & Sons, Inc.
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    Predictions for oxygen supply control to enhance population stability of engineered production strains (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 275-285 
    Details
    ISSN: 0006-3592
    Keywords: Escherichia coli ; amino acids ; linear optimization ; metabolic fluxes ; metabolic engineering ; culture stability ; oxygen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The simultaneous growth and product formation in a microbial culture is an important feature of several laboratory, industrial, and environmental bioprocesses. Metabolic burden associated with product formation in these bioprocesses may lead to growth advantage of a nonproducing mutant leading to a loss of the producing population over time. A simple population dynamics model demonstrates the extreme sensitivity of population stability to the engineered productivity of a strain. Here we use flux balance analysis to estimate the effects of the metabolic burden associated with product secretion on optimal growth rates. Comparing the optimal growth rates of the producing and nonproducing strains under a given processing condition allows us to predict the population stability. In order to increase stability of an engineered strain, we determine processing conditions that simultaneously maximize the growth rate of the producing population while minimizing the growth rate of a nonproducing population. Using valine, tryptophan, and lysine production as specific examples, we demonstrate that although an appropriate choice of oxygenation may increase culture longevity more than twofold, total production as governed by economic criterion can be increased by several orders of magnitude. Choice of optimal nutrient and oxygen supply rates to enhance stability is important both for strain screening as well as for culture of engineered strains. Appropriate design of the culture environment can thus be used to enhance the productivity of bioprocesses that use engineered production strains. © 1994 John Wiley & Sons, Inc.
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    Optimization of an industrial microalgae fermentation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 314-320 
    Details
    ISSN: 0006-3592
    Keywords: Spongiococcum exetricicum ; fed-batch fermentation ; fermentation ; microalgae fermentation ; feedback control ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimization of cellular productivity of an industrial microalgae fermentation was investigated. The fermentation was carried out at Coors Biotech Products Company, Fort Collins, Colorado. A mathematical model was developed based on the data collected from pilot plant test runs at different operating conditions. Pontryagin's maximum principle was used for determining the optimal feed policy. A feedback control algorithm was also studied for maximizing the cellular productivity. During continuous operation, the optimum dilution rate was determined by an adaptive optimization scheme based on the steepest descent technique and a recursive least squares estimation of model parameters. A direct search algorithm was also applied to determine the optimum feed rate. Comparison of the theoretical results of the different optimization schemes revealed that the direct search algorithm was preferable because of its simplicity. The experimental results of real time application of the feedback algorithm agreed fairly well with those of the theoretical analyses. © 1994 John Wiley & Sons, Inc.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440701
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    Ribosomal protein limitations in Escherichia coli under conditions of high translational activity (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 388-398 
    Details
    ISSN: 0006-3592
    Keywords: ribosome synthesis ; Escherichia coli ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Details of the mechanism for ribosome synthesis have been incorporated in the single-cell Escherichia coli model, which enable us to predict the amount of protein synthesizing machinery under different environmental conditions. The predictions agree quite well with available experimental data. The model predicts that ribosomal protein limitations are important when the translational apparatus is in high demand. Ribosomal RNA synthesis is induced by an increase in translational activity, which, in turn, stimulates ribosomal protein synthesis. However, as the demand increases still more, the ribosomal protein mRNA must compete with the plasmid mRNA for ribosomes, and the efficiency of translation of ribosomal proteins is reduced. © 1994 John Wiley & Sons, Inc.
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    Effects of intermolecular thiol-disulfide interchange reactions on bsa fouling during microfiltration (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 972-982 
    Details
    ISSN: 0006-3592
    Keywords: membrane fouling ; microfiltration ; protein aggregation ; sulfhydryl reactions ; protein separation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several studies have shown that one of the critical factors governing protein fouling of microfiltration membranes is the presence of denaturedand/or aggregated protein in the bulk solutions. Experiments were performed to evaluate the role of intermolecular disulfide interchange reactionson protein aggregation and membrane fouling during stirred cell microfiltration of bovine serum albumin (BSA). The flux decline during BSA filtration was quite dramatic due to the formation of a protein deposit thatfully covered the membrane pores. This flux decline could be completely eliminated by capping the free sulfhydryl group present on the BSA with eithera carboxymethyl or cysteinyl group, demonstrating the critical importance of this free thiol in the intermolecular aggregation reactions and, in turn, protein fouling. BSA aggregation during storage could be reduced by the addition of metal chelators (EDTA and citrate) or dithiothreitol, orby storage at lower pH (7.0) these solutions all had a significantly lower rate of fouling upon subsequent filtration. This behavior is completely consistent with the known chemistry of the thiol-disulfide interchange reaction, demonstrating that an understanding of these intermolecular (aggregation) reactions can provide a rational framework for the analysis and control of protein fouling in these membrane systems. © 1994 John Wiley & Sons, Inc.
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    Hyperosmotic hbridoma cell cultures: Increased monoclonal antibody production with addition of glycine betaine (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 991-998 
    Details
    ISSN: 0006-3592
    Keywords: monoclonal antibodies ; hybridoma cells ; hyperosmotic stress ; glycine betaine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When mouse hybridoma cells were grown in culture media which were made hyperosmotic through the addition of NaCl or sucrose, the specific rate of antibody production increased with medium osmolality, reaching approx. 1.9 times the level obtained at physiological osmolality. However, due to a simultaneous reduction of the maximal cell density in the hyperosmotic media, the effect of the increased production rate did not give significant increases in the maximum antibody titer obtained in the cultures. When the osmoprotective compound, glycine betaine, was included in the NaCl- or sucrose-stressed cultures, the specific antibody production rate wasincreased up to 2.6-fold and maximum antibody titer up to twofold over that obtained in the control culture (physiological osmolality). A similar pattern of response was observed when other osmoprotective compounds (sarcosine, proline, glycine) were added to NaCl-stressed hybridoma cell cultures. For the present experiments, the results suggest that medium osmolality, rather than growth rate, will determine the specific antibody production rate by hybridoma cell line 6H11 growing in hyperosmotic culture media. © 1994 John Wiley & Sons, Inc.
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    The influence of dissolved oxygen tension on the synthesis of the antibiotic difficidin by bacillus subtilis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1007-1012 
    Details
    ISSN: 0006-3592
    Keywords: difficidin ; oxydifficidin ; Bacillus subtilis ; dissolved oxygen tension ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The antibiotic, difficidin, and its hydroxylated derivative oxydifficidin, were synthesized by cultures of Bacillus subtilis grown on a complex medium. Maximum titers of about 200 and 130 mg/L, respectively, were obtained. In fermentations where the dissolved oxygen tension (DOT) was controlled, the maximum specific growth rate was only reduced below 5% air saturation. DOT had little effect on the volumetric rateof synthesis of oxydifficidin but greatly influenced the rate for difficidin, which was reduced at DOT values below 40% air saturation. © 1994 John Wiley & Sons, Inc.
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    Oxygen requirements and mass transfer in hairy-root culture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 880-887 
    Details
    ISSN: 0006-3592
    Keywords: plant tissue culture ; hairy roots ; Atropa belladonna ; oxygen mass transfer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxygen mass transfer in clumps of Atropa belladonna hairy roots was investigated as a function of root density and external flow conditions. Convection was the dominant mechanism for mass transfer into root clumps 3.5 to 5.0 cm in diameter; Peclet numbers inside the clumps ranged from 1.4 × 103 to 7.1 × 104 for external superficial flow velocities between 0.4 and 1.4 cm s-1. Local dissolved-oxygen levels and rates of oxygen uptake were measured in aflow chamber and in bubble column and stirred bioreactors. When air was used as oxygen source, intraclump dissolved-oxygen tensions ranged from90% to 100% air saturation at high external flow velocity andlow root density, to less than 20% air saturation in dense root clumps. Specific oxygen-uptake rate declined with increasing root density. When external boundary layers around individual roots were eliminated byforcing liquid through the clumps at superficial velocities between 0.2 and1.0 cm s-1, internal dissolved-oxygen tension was maintained at 95% to 100% air saturation and rate of oxygen uptake at 1.6 × 10-6 g g-1 s-1 dry weight. Liquid culture of single A. belladonna hairy roots was used to investigate the effect of dissolved-oxygen tensionon root growth and morphology. Total root length and number of root tips increased exponentially at oxygen tensions between 70% and 100%air saturation. Specific growth rate increased with oxygen tension up to 100% air saturation; this result demonstrates that hairy roots aeratedwithout oxygen supplementation are likely to be oxygenlimited. No growth occurred at 50% air saturation. Growth of hairy roots proceeded with an average length per tip of about 1 cm; this value was essentially independent of dissolved-oxygen tension between 70% and 100% air saturation. © 1994 John Wiley & Sons, Inc.
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    Evaluation of the hok/sok killer locus for enhanced plasmid stability (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 912-921 
    Details
    ISSN: 0006-3592
    Keywords: plasmid stability ; cloned gene ; hok/sok locus ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effectiveness of the hok/sok plasmid stability locus and mechanism of cloned-gene loss was evaluated in shake-flask cultures. Addition of the hok/sok locus dramitically increasedapparent plasmid segregational stability to the hok/sok- control. In terms of the number of generations before 10%of the population became plasmid-free, segregational stability was increased by 11- to 20-fold in different media in the absence of induction of the cloned-gene (hok/sok+ plasmid stable for over 200 generations in all media tested). With constant expression of β-galactosidase in the absence of an tibiotic, the segregational stability of the plasmid containing hok/sok was incresed more than 17- to 30-fold when β-galactosidase was expressed at 7-15 wt % of total cell protein. Although the hok/sok system stabilized the plasmid well infour different media (Luria-Bertani (LB), LB glucose, M9C Trp, and a representative fedbatch medium), the ability of hok/sok to maintain the plasmid with induction of the cloned gene decreased as the complexity of the media increased. This result is better interpreted in terms of the influence of cloned-gene expression on plasmidmaintenance; plasmid segregational stability decreased linearly as specificβ-galactosidase activity increased. © 1994 John Wiley & Sons, Inc.
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    Efficient specific release of periplasmic proteins from Escherichia coli using temperature induction of cloned kil gene of pMB9 (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1074-1082 
    Details
    ISSN: 0006-3592
    Keywords: pL promote ; kil gene ; expression plasmid ; periplasmic proteins, release ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have cloned the kil gene of pMB9 under control of the tightly regulated leftward promoter (pL) of coliphage λ. Three types of plasmids were constructed. In all cases the activity of the λ promoter is controlled by a thermosensitive cl repressor (product of the c/857 gene) supplied form a resident defective prophage or cloned onto a compatible p 15A-derived plasmid. Induction of the kil protein is brought about by a temperature shift of the culture from 28°C to 42°C. Plasmid pPLc28K1 contains the kil gene including its natural ribosome-binding site and preceded by a transcription termination site. Using a bacterial strain with antitermination properties (e.g., M5219), periplasmic proteins can upon induction be gradually the growth of the host strain. The second plasmid pPLc321K1, contains the kil-coding sequence preceded by an engineered ribosome binding site derived from the attenuator of the Escherichia coli tryptophan operon. With this plasmid induction of the Kil protein is very rapid and specific release of the periplasmic proteins in essentially complete within 30 min after induction. In a third construct, pcl857K1, the pL-kil cassette together with c/857 allele are present on the same replicon, which is compatible with ColE1-derived expression vectors. This configuration allows accumulation in the periplasm of cloned gene products, induced by, e.g., tac or trp promoters at low temperature and subsequent release into the medium following increase of the temperature of the culture. Under repressed conditions (growth at low temperature) all plasmids are perfectly stable in a large number of E. coli strains tested, also when cultivated on a 20-L fermentor scale. Controlled, heat-induced release of periplasmic proteins is highly specific and applicable at relatively high cell densities. The method therefore is an attractive alternative to cumbersome osmotic shock procedures for large-scale cultures. © 1994 John Wiley & Sons, Inc.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430801
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    Preface Tissue Engineering and Cell Therapies: II (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 683-683 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430802
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    Microencapsulated human bone marrow cultures: A potential culture system for the clonal outgrowth of hematopoietic progenitor cells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 734-739 
    Details
    ISSN: 0006-3592
    Keywords: bone marrrow cultures ; hematopoietic progenitor cells ; microencapsulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Currently the most successful methods for culturing human hematopoietic cells employ some form of perfused bioreactor system. However, these systems do not permit the clonal outgrowth of single progenitor cells. Therefore, we have investigated the use of alginate-poly-L-lysine microencapsulation of human bone marrow, combined with rapid medium exchange, as a system that may overcome this limitation for the purpose of studying the kinetics of progenitor cell growth. We report that a 12 to 24-fold multilineage expansion of adult human bone marow cells was achieved in about 16 to 19 days with this system and that visually identifiable colonies within the capsules were responsible for the increase in cell number. The colonies that represented the majority of cell growth originated from cells that appeared to be present in a frequency of about 1 in 4000 in the encapsulated cell population. These colonies were predominantly granulocytic and contained greater than 40,000 cells each. Large erythroid colonies were also present in the capsules, and they often contained over 10,000 cells each. Time profiles of the erythroid progenitor cell density over time were obtained. Burst-forming units erythroid (BFU-E) peaked around day 5, and the number of morphologically identifiable erythroid cells (erythroblasts through reticulocytes) peaked on day 12. We also report the existence of a critical inoculum density and how growth was improved with the use of conditioned medium derived from a microcapsule culture initiated above the critical inoculum density. Taken together, these results suggest that microencapsulation of human hematopoietic cells allows for outgrowth of progenitor, and possible preprogenitor, cells and could serve as a novel culture system for monitoring the growth and differentiation kinetics of these cells.
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    Effects of substratum morphology on cell physiology (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 764-771 
    Details
    ISSN: 0006-3592
    Keywords: surface morphology ; photolithography ; substrata, grooved ; Cell shape ; cell spreading ; cell adhesion ; DNA Synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Among the host of substratum properties that affect animal cell behavior, surface morphology has received relatively little attention. The earliest effect of surface morphology on animal cells was discovered almost a century ago when it was found that cells became oriented in response to the underlying topography. This phenomenon is now commonly known as contact guidance. From then until very recentrly, little progress has been made in understanding the role of surface morphology on cell behavior, primarily due to a lack of defined surfaces with uniform morphologies. This problem has been solved recently with the development of photolithographic techniques to prepare substrata with well defined and uniform surface morphologies. Availability of such surfaces has facilitated systematic in vitro experiments to study influence of surface morphology on diverse cell physiological aspects such as adhesion, growth, and function. For example, these studies have shown that surfaces with uniform multipls parallel grooves can enhance cell adhesion by confining cells in grooves and by mechanically interlocking them. Several independent studies have demosterated that cell shape is a major determinant of cell growth and function. Because surface morphology has been shown to modulate the extent of cell spreading and cell shape, its effects on cell growth and function appear to be mediated via this biological coupling between cell shape and function. New evidence in the cell biology literature is emerging to suggest that surface morphology could affect other cell behavioral properties such as post-translational modifications. Further elucidation of such effects will enable better designs for implant and cell culture substrata.
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    N-acetylglucosamine and adenosine derivatized surfaces for cell culture: 3T3 fibroblast and chicken hepatocyte response (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 801-809 
    Details
    ISSN: 0006-3592
    Keywords: 3T3 Fibroblast ; chicken hepatocytes ; cell-polymer interactions ; N-acetylglucosamine derivatized polystyrene ; hepatocytes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 3T3 fibroblasts and primary chicken hepatocytes were cultured on derivatized polystyrene surfaces to examine the effect of cell-specific ligands on cellular morphology and growth. Surfaces were prepared by derivatizing chloromethylated polystyrene with N-acetylglucosamine (GlcNAc; recognized by the chicken asialoglycoprotein receptor) and adenosine (not recognized by adult hepatocytes). These surfaces were compared with tissue culture polystyrene (TCPS), acid-cleaned glass, and the unmodified chloromethylated polystyrene. The spreading, cytoskeletal structure and growth of the fibroblasts following attachment to these surfaces were examined. The extent of attachment, total protein levels, and DNA contents for surfaces-attached chicken hepatocytes were also measured. Fibroblast spreading was greatest on polymer surfaces derivatized with GlcNAc, whereas cytoskeletal structure and growth rate were independent of surface chemistry. Although chicken hepatocytes attached most efficiently to the GlcNAc derivatized polymer, the total protein and DNA levels of the surface-attached cells were not affected. In anticipation of the application of these polymers for cell culture and hybrid artificial organ design, the GlcNAc-derivatized polystryrene was fabricated into porous microcarriers. Fibroblasts grew avidly on the microcarriers, whereas chicken hepactocytes adhered well to the formed large aggregates arounds the microcarriers.
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    Filtration-based perfusion of hybridoma cultures in protein-free medium: Reduction of membrane fouling by medium supplementation with DNase I (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 833-846 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, a filtration-based perfusion process was developed for the production of monoclonal antibodies (IgM) by suspended hybridoma cells grown in protein-free medium. It was found that the use of protein-free medium for perfusion culture generated the formation of numerous visible suspended particles consisting of dead cells and cellular debris aggregated into fibrous material. Surprisingly high apparent viabilities were observed in such protein-free cultures. In addition, membrane fouling occurred more rapidly in protein-free medium than in conventional serum-supplemented medium. By the addition of deoxyribonuclease I (DNase I) to the protein-free medium, it was possible to prevent the formation of aggregates and to follow the evolution of the total cell population more accurately. Moreover, DNase I significantly reduced the fouling of filtration membranes, and that, for two different types of separation systems (cross-flow and vortex-flow filtration) and two different types of membranes (polycarbonate and hydrophilized polysultone). From these results, it is clear that the presence of DNA fragments liberated following cellular death is playing an important role in membrane fouling. Longevity of filtration membranes was found to be considerably greater using a vortex-flow filtration module than with a static plate-and-frame cross-flow filtration module. The use of vortex-flow filtration of conjuction with DNase I allowed maintenance of perfusion cultures for more than 1 month without membrane fouling or antibody retention and with a constant permeate IgM concentration of 250 mg/L. Hybridomacells appeared to gradually adapt to increasing rotational speed in the vortex-flow filtration module.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260431001
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    Facilitated transport of lactic acid in a stirred transfer cell (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 907-912 
    Details
    ISSN: 0006-3592
    Keywords: lactic acid ; liquid membrane ; facilitated transport ; extraction ; organic acids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The application of liquid membrane extraction to the recovery of lactic acid from model systems and fermentation media was investigated. An experimental study of the facilitated transport of lactic acid using ALIQUAT 336 as a mobile carrier in a stirred transfer cell is reported. The effect of stirring speed, initial lactic acid concentration, carrier concentration, and NaCl as a reagent in the acceptor phase are considered. © 1994 John Wiley & Sons, Inc.
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    Enhancement of oxygen transfer in highly viscous non-newtonian fermentation broths (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1115-1121 
    Details
    ISSN: 0006-3592
    Keywords: oxygen transfer ; perforated plate ; external-loop airlift ; non-Newtonian media ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of short draft tubes covered by perforated plates on gas-liquid mass transfer was examined in external-loop airlift bioreactors. The volumetric mass transfer coefficients in a model external-loop airlift bioreactor were measured with water and non-Newtonian media. It was found that introduction of draft tubes covered with perforated plates in the riser significantly improved the mass transfer rate, particularly in higher viscous non-Newtonian fermentation media. The enhancement of mass transfer rate might be due mainly to an increase in bubble coalescence and redispersion. © 1994 John Wiley & Sons, Inc.
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    Use of plant material for the decontamination of water polluted with phenols (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1132-1139 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Plant materials were found useful in the decontamination water polluted with phenolic contained in the plant tissue. The enzymes mediated oxidative coupling of the pollutants, followed by precipitation of the formed polymers from the aqueous phase. An industrial wastewater contaminated with 2,4-dichlorophenol (up to 850 ppm) and other chlorinated phenols was successfully treated using minced horseradish, potato, or white radish (amended with H2O2). Horseradish-mediated removal of 2,4-dichlorophenol from model solutions was comparable with that achieved using purified horseradish peroxidase. In addition, horseradish could be reused up to 30 times. Due to the apparent ease of application, the use of plat material may present a breakthrough in the enzyme treatment of contaminated water. © 1994 John Wiley & Sons, Inc.
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    Crossflow filtration of yeast broth cultivated in molasses (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1094-1101 
    Details
    ISSN: 0006-3592
    Keywords: crossflow filtration ; microfiltration ; Saccharomyces cerevisiae ; molasses ; backwashing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A broth of yeast cells cultivated in molasses was crossfiltered with a thin-channel module. The permeation flux gradually decreased at a constant cell concentration. The flux was much lower than that obtained for yeast broth cultivated in yeast extract, polypeptone, and dextrose (YPD) medium during the filtration. The flux did not depend on the membrane pore size (0.45 to 5 μm). The steady-state flux was one-twentieth that calculated for a cake filtration mode from the amount of cake per unit filtration area and the specific resistance of the cake measured in a dead-end filtration apparatus. The lower flux was due to small particles (most of which were less than 1 μm in diameter) in the molasses. The mehanism of crossflow filtration of broths of yeast cells cultivated in molasses was clarified by analysis of the change in flux with time and observations with scanning electron microscopy. At the initial stage of crossflow filtration the yeast cells and particles from the molasses were deposited on the membrane to form the molasses were deposited on the membrane to form a cake in a similar way to dead-end filtration. After the deposition of cells onto the membrane ceased, the fine particles from molasses formed a thin layer, which had higher resistance than the cake formed next to the membrane. The backwashing method was effective to increase the flux. The flux increased low when the pore size was 0.45 to 0.08 μm, but using larger pores of 3 to 5 μm it returned almost to the bases line. © 1994 John Wiley & Sons, Inc.
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    Stabilizing effect of amphiphilic excipients on the freeze-thawing and freeze-drying of lactate dehydrogenase (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1102-1107 
    Details
    ISSN: 0006-3592
    Keywords: freeze-drying ; freeze-thawing ; amphiphilic excipients ; lactate dehydrogenase ; stabilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of amphiphilic excipients on the inactivation of lactate dehydrogenase (LDH) during freeze-thawing and freeze-drying were studied. Some amphiphilic excipients such as hydroxypropyl-β-cyclodextrin (HP-β-CD), CHAPS, polyethylene glycol (PEG) 3350, and sucrose fatty acid monoester prevented LDH inactivation during freeze-thawing and freeze-drying at a lower concentration than sugars and amino acids. Polyoxyethylene 9 lauryl ether and PEG 400 protected LDH during freeze-thawing but not during freeze-drying. The buffer concentration of the solution to be freeze-dried (10, 50, and 200 mM) affected the stabilizing effect of trehalose, but not that of HP-β-CD. © 1994 John Wiley & Sons, Inc.
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    Continuous propionate production from whey permeate using a novel fibrous bed bioreactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1124-1130 
    Details
    ISSN: 0006-3592
    Keywords: propionic acid fermentation ; Propionibacterium acidipropionici ; immobilized cell ; fibrous bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous production of propionate from whey lactose by Propionibacterium acidipropionici immobilized in a novel fibrous bed bioreactor was studied. In conventional batch propionic acid fermentation, whey permeate without nutrient supplementation was unable to support cell growth and failed to give satisfactory fermentation results for over 7 days. However, with the fibrous bed bioreactor, a high fermentation rate and high conversion were obtained with plain whey permeate and de-lactose whey permeate. About 2% (wt/vol) propionic acid was obtained from a 4.2% lactose feed at a retention time of 35 to 45 h. The propionic acid yield was ∼46% (wt/vol) from lactose. The optimal pH for fementation was 6.5, and lower fermentation rates and yields were obtained at lower pH values. The optimal temperature was 30°C, but the temperature effect was not dramatic in the range of 25 to 35°C. Addition of yeast extract and trypticase to whey permeate hastened reactor startup and increased the fermentation rate and product yields, but the addition was not required for long-term reactor performance. The improved fermentation results with the immobilized cell bioreactor can be attributed to the high cell density, ∼50 g/L, attained in the bioreactor, Cells were immobilized by loose attachement to fiber surfaces and entrapment in the void spaces within the fibrous matrix, thus allowing constant renewal of cells. Consequently, this bioreactor was able to operate continuously for 6 months without encountering any clogging, degeneration, or contamination problems. Compared to conventional batch fermentors, the new bioreactor offers many advantages for industrial fermentation, including a more than 10-fold increase in productivity, acceptance of low-nutrient feedstocks such as whey permeate, and resistance to contamination. © 1994 John Wiley & Sons, Inc.
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    Communication to the editor. Application of the cross-regulation system as a metabolic switch (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1190-1193 
    Details
    ISSN: 0006-3592
    Keywords: metabolic switch ; cross-regulation ; metabolic flux regulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability to switch metabolic flow from one pathway to another at a desired point in a bioprocess expands the horizons of metabolic engineering. Such an externally inducible switch can be realized by embedding synthetic operons behind tow corss-regulated promoters. This results in coordinated cessation of transcription of one operon while transcription of a second operon is simultaneously activated. The ability to effect such coordinated and inverse control of transcription of two operons has been illustrated experimentally using a model construct containing two different reporter genes, Vitreoscilla hemoglobin (VHb) and chloramphenicol acetyltransferase (CAT), fused to λPL and tac promoters, respectively, along with corresponding repressor genes in a cross-regulation configuration. Only VHb production was observed preinduction, and postinduction only CAT was produced. The framework presented here and its obvious extensions can be used with different combinations of promoter systems and synthetic operon constructs to achieve complicated metabolic flux regulation in diverse host. © 1994 John Wiley & Sons, Inc.
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    Two-phase airlift fermentor operation with elicitation for the enhanced production of enzophenanthridine alkaloids in cell suspensions of Escherichia californica (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 14-20 
    Details
    ISSN: 0006-3592
    Keywords: elicitation ; benzophenanthridine alkaloids ; airlift fermentor ; Escherichia californica ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Approaches to increasing the productivity of benzophenanthridine alkaloids in suspension cultures in Escherichia californica were made in an airlift fermentor under different culture conditions. Elicitation with yeast extract elicitor reduced the time required to obtain a certain amount of alkaloid production. In a two-phase airlift fermentor with compounded silicone fluid, total alkaloid concentration in silicone fluid was 153.1 mg/L and that in the aqueous cellular phase was 8.2 mg/L at day 21 from inoculation. The large accumulation capacity of silicone fluid made it possible to store correspondingly large amounts of total alkaloid and increased the alkaloid production. Act day 21 from inoculation, the volumetric alkaloid productivity and the netproduction in a two-phase airlift fermentor were 1.4 and 1.5 times higher than those of normal airlift fermentor operation. This performance was furthermore enhanced by elicitation. Elicitation in two-phase airlift fermentor operation increased the volumetric productivity and the new production 3.3- and 3.5-fold compared to those of normal airlift fermentor operation. © 1994 John Wiley & Sons, Inc.
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    Affinity cross-flow filtration: Purification of IgG with a novel protein a affinity matrix prepared from two-dimensional protein crystals (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 55-65 
    Details
    ISSN: 0006-3592
    Keywords: crystalline bacterial cell surface layers ; S-layers ; Protein A ; affinity cross-flow filtration ; IgG purification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this article, we describe the use of 1- to 2-μm sized affinity microparticles for the isolation and purification of IgG from artificial IgG-human serum albumin mixtures and clarified hybridoma cell culture supernatants by affinity cross-flow filtration. Affinity microparticles were prepared from cell wall fragments of Clostridium thermohydrosulfuricum L111-69, in which the peptidoglycan-containing layer was completely covered with a hexagonally ordered S-layer lattice. 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 Protein A molecules formed a monomolecular layer on the outermost surface of the S-layer lattice. Affinity microparticles were found to withstand high centrifugal and shear forces and revealed no Protein A leakage or S-layer protein release under cross-flow conditions between pH 2 to 12. The IgG-binding capacity of affinity microparticles was investigated under crossflow conditions and compared with that obtained in batch adsorption processes. © 1994 John Wiley & Sons, Inc.
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    A fast bioassay for phytotoxicity measurements using immobilized photosynthetic membranes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 178-183 
    Details
    ISSN: 0006-3592
    Keywords: bioassay ; phytotoxicity ; photosynthesis ; immobilized membranes ; oxygen evolution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The potential of thylakoid membranes immobilized in an albumin-glutaraldehyde crosslinked matrix in a fast bioassay for phytotoxicity measurements in aqueous samples is studied. Free and immobilized preparations are compared for their electron transport activity measured as the initial rate of oxygen evolution with 2,5-cichlorobenzoquinone as the artificial electron acceptor. Immobilized thylakoids were much stable under storage conditions; in the dark, at 4°C, they were fully stable in terms of photosynthetic activity for a period of 200 h. The immobilized membranes were as sensitive as the free thylakoids for the detection of most of the compounds tested (metal cations, sulfite, nitrite, and herbicides), all known as inhibitors of photosynthetic electron transport. In some instances, the immobilized preparations were even more sensitive than the free counterparts. The sensitivity could be further increased by lowering chlorophyll concentration in the assay. The short incubation period required (∼10 to 15 min) and the small volume of the assay (3 mL) suggest that this type of material should be useful in the detection of locations or effluents with phytotoxic character. © 1994 John Wiley & Sons, Inc.
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    Biological destruction of CCI4: II. Kinetic modeling (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 211-218 
    Details
    ISSN: 0006-3592
    Keywords: kinetic model ; denitrify ; carbon tetrachloride ; destruction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A denitrifying consortium capable of transforming carbon tetrachloride (CCI4) was cultured from an aquifer soil sample from the U.S. Department of Energy's Hanford Site in southeastern Washington State. A mathematical description of the kinetics of CCI4 destruction by this microbial consortium is presented, and its prediction are compared to experimental data. The model successfully predicted the concentrations of acetate, nitrate, nitrite, biomass, and CCI4 for all 12 experiments (a total of 60 concentration-vs.-time data sets). In addition, no statistically significant interactions exist between parameter values and individual test conditions. The ability of the model to predict the results of a treatability test for CCI4 degradation in Hanford groundwater, without adjusting any model parameters, is discussed. © 1994 John Wiley & Sons, Inc.
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    Biodegradation process development using a bacterial cytochrome in vivo (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 248-255 
    Details
    ISSN: 0006-3592
    Keywords: cytochrome P-450cam monooxygenase ; bioaugmenattion ; halocarbon degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pseudomonas putida PpG786 that contains the inducible enzyme system cytochrome P-450cam is considered for use as specialized biomass fore detoxification of hazardous hydrocarbons. The test substrate 1,2-dibromochloropropane (DBCP) is used to assess the organohalide degradation activity of P. Putida PpG786. Activity was found to be a strong function of intracellular heme content, variables which affect the culturing and processing of the cells, and oxygen tension in the degradation incubation medium. The lifetime for maintaing active biomass in chemostat washout operation, after including substrate was removed and then restarted, was also studied. These results indicate that initial activity of the P. Putida biomass is high enough, and decays slowly enough, so that industrial wastewater treatment at the operating conditions of a sequencing batch reactor (SBR) could remove hazardous compounds. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440214
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    Microfiltration of streptococcal fermentation broths: Study of the factors affecting the concentration effect (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 270-275 
    Details
    ISSN: 0006-3592
    Keywords: cross-flow ; microfiltration ; concentration effect ; streptokinase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Streptokinase (SK) recovery from streptococcal fermentation broth by cross-flow microfiltration has been studied. Recovery of SK in the filtrate, independent of the volumetric concentration factor, is approximately two-fold lower than the initial SK activity in the fermentation broth; moreover, the SK activity in the retentate increase during the process, reaching a concentration factor of 2.73. These results show that the membrane works more as an ultrafiltration membrane, with rejection of S = 0.6, than as a microfiltration membrane. Under filtration conditions, the membrane permeation rate decreased with time. This decreased could be explained by deposition and interaction of material onto/with the membrane resulting in the concentration of permeable products. Studies of the individual concentration factors for the main streptococcal exocellular proteins, indicate clearly that the concentration of the proteins during the microfiltration process is independent of the size of the proteins, suggesting that other factors, such as charge and hydrophobicity, along with concentration-polarization, should be taken also into account for the understanding of this phenomenon. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440303
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  • 99
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    Electronic Resource
    Transient responses of hybridoma cells in continuous culture to step changes in amino acid and vitamin concentrations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 303-321 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma metabolism ; continuous culture ; suspension culture ; antibody productivity ; amino acids ; vitamins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of step-change increase in the concentrations of amino acids and vitamins on the metabolism, growth, and antibody productivity of a murine hybridoma cell line grown in continuous culture on serum-free medium are presented. Additions of the amino acids cysteine with methionine, tryptophan, and isoleucine with valine and vitamin B12 (as cyanocobalamin) resulted in significant increases in viable cell concentrations. Additions of aspartate with asparagine, and threonine with vitamin B1 (as thiamine hydrochloride) resulted in significant increases in final antibody concentrations. Substantial decrease in the fraction of amino acid nitrogen excreted as ammonia occurred upon supplementation with three times the normal concentrations of branched chain amino acids. Decreases in the fraction of amino acid nitrogen converted to ammonia were paralleled by increases in the fraction converted to alanine. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440308
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  • 100
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    Flotation of cadmium-loaded biomass (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 354-360 
    Details
    ISSN: 0006-3592
    Keywords: flotation ; streptomycetes ; cadmium ; biosorption ; ζ- potential ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biosorption of heavy metal ions such as Cd2+ by dead biomass has been recognized as a potential alternative to existing removal technologies applied to wastewater treatment. Two bacterial strains were studied in the laboratory, streptomyces griseus and S. clavuligerus, an industrial by-product. Both washed and unwashed samples were examined. Foam flotation proposed in this work as the separation state following biosorption. Effective biomass separation was conducted in the presence of a frother, ethanol. The pH of the solution was a crucial parameter for flotation and also for metal binding. Other basic parameters of flotation examined were the initial cadmium concentration in the dilute aqueous solution and the quantity of biomass used. A study of ζ-potential measurements of the actinomycetes was carried out under the conditions used in the separation; surface tension was also measured. These provided useful information on the process. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440313
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