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  • 11
    Electronic Resource
    Electronic Resource
    Enhanced disruption of Candida utilis using enzymatic pretreatment and high-pressure homogenization (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 46-56 
    Details
    ISSN: 0006-3592
    Keywords: enzymatic lysis ; homogenization, high-pressure ; Candida utilis ; cell wall disruption ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The enhancement of the overall disruption of a native strain of Candida utilis (ATCC 9226) was studied using a combination of two methods, namely, pretreatment in the form of partial enzymatic lysis by Zymolyase followed by mechanical disruption in a Microfluidizer high-pressure homogenizer. The cells were grown in both batch and continuous cultures to examine the effect of specific growth rate on disruption. Cell suspensions ranging in concentration from 7 to 120 g DW/L were disrupted with and without enzymatic pretreatment. For yeast grown in batch culture, final total disruption obtained using the combined protocol approached 95% with four passes at a pressure of 95 MPa, as compared with only 65% disruption using only mechanical homogenization. A modified model was developed to predict the fraction disrupted by the enzymatic pretreatment-mechanical homogenization two-stage process. Predicted disruptions agreed favorably with experimental observations (maximum deviation of 20%) over a wide range of operating conditions. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430107
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  • 12
    Electronic Resource
    Electronic Resource
    Double inhibition model for degradation of phenol by Pseudomonas putida Q5 (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 560-567 
    Details
    ISSN: 0006-3592
    Keywords: phenol degradation ; Pseudomonas putida ; inhibition model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A semiempirical model, based on the presence of an inhibitory intermediate metabolite excreted to the broth, was developed to better predict the dynamic responses to shock loadings of Pseudomonas putida Q5 degrading phenol. Compared to the Haldane equation, the new model exhibited better prediction capabilities for a broad range of inlet concentration and dilution rate step changes. The experiments were performed at 10° and 25°C and ranged from stable responses to washouts. The time delays observed experimentally were successfully predicted with the dual-inhibition model and a very good agreement with the observed phenol profile also was found in a pulse experiment. A possible intermediate metabolite was detected by HPLC analyses based on the high correlation shown with the predicted inhibitory intermediate metabolite in the model. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 560-567, 1998.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Oxygen absorption in stirred tanks: A correlation for ionic strength effects (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 755-782 
    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 new correlation is given for the prediction of the volumetric coefficient for mass transfer (KLa) in stirred tanks from dispersed gas bubbles to basal salt solutions of ionic strengths representative of fermentation media. The correlation includes the effects of both the operating parameters (agitation power per unit volume and gas superficial velocity) and the physicochemical properties of the system: interfacial tension, viscosity, density, diffusion, coefficient and, in particular, ionic strength. The effect of the latter was found to be most significant in the Newtonian systems of water-like viscosity investigated; no previous correlations have included the effect of ionic strength. KLa values were determined by using a dissolved oxygen probe to monitor the steady-state oxygen tension in continuous flow experiments, and/or the rate of change of oxygen tension in unsteady-state semibatch experiments. In the latter cases, results were computed by a nonlinear, least squares computer program which fitted the experimental data to a model of probe transient response characteristics. The general applicability of the model and the computational procedure was verified by comparing the results to those obtained with the same electrolyte solution in the steady-state mode. The experiments were run over a wide range of agitation power inputs, including those typical of both soluble- and insoluble-substrate fermentations. The correlation appears to be valid for both oxygen mass transfer with and without homogeneous chemical reaction in the liquid phase; in the former case, for example, sulfite oxidation, knowledge of the chemical reaction enhancement factor is required. In addition to predicting oxygen transfer capabilities, the correlation may be used for other sparingly soluble gases of interest in fermentation systems, such as methane, hydrogen, and carbon dioxide.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260150409
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  • 14
    Electronic Resource
    Electronic Resource
    Disruption of native and recombinant Escherichia coli in a high-pressure homogenizer (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 1330-1342 
    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 disruption of native and recombinant strains of Escherichia coli was studied using a high-pressure homogenizer (Microfluidizer). The cells were grown in both batch and continuous fermentations. Cell suspensions ranging from 4 to 175 g dry wt/L were investigated at disruption pressures ranging from 30-95 MPa and at up to five passes. For both types of cells, the fraction of cells disrupted was dependent on the growth rate and concentration of the cells, the disruption pressure, and the number of passes through the disrupter. A model is presented that correlates the fractional disruption with these operating variables. The recombinant strain disrupted more readily than the native strain; 95 to 98% disruption of the former was achieved in two to three passes at a pressure of 95 MPa.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260331016
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  • 15
    Electronic Resource
    Electronic Resource
    Evaluation of organosolv processes for the fractionation and modification of corn stover for bioconversion (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 29 (1987), S. 572-581 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Corn stover was pretreated for compositional fractionation and structural modification for maximum conversion of carbohydrate to soluble sugars. The process scheme consisted of three steps: (1) mild prehydrolysis in dilute sulfuric acid, (2) delignification with various organosolv solvents, and (3) enzymatic hydrolysis in an agitated bead reactor. Prehydrolysis of corn stover can be achieved at temperatures ranging from 95 to 120°C, which is a much milder condition than must be applied to wood. Various organosolv solvents, including several alcohols with acid as catalyst, ethylene glycol, and its derivatives, and amines were used for delignification of the prehydrolyzed corn stover. Aromatic alcohols were found to be more effective in solubilizing the prehydrolyzed corn stover than were the aliphatic alcohols. Butanol was the most effective among the aliphatic alcohols; on the other hand, phenol was the best among the aromatic alcohols. Ethylene glycol, methylcellosolv, and ethylcellosolv were effective in solubilizing the prehydrolyzed corn stover but not for enhancing the enzymatic hydrolysis. Various amines achieved delignification at the mild temperature of 95°C, but they tended to solubilize substantial amounts of carbohydrate in addition to lignin. n-Butylamine was effective in enhancing the conversion during enzymatic hydrolysis; it was a good delignifying agent as well as one that achieved a concomitant swelling of the cellulose structure. The low enzymic conversion (20-37%) of prehydrolyzed and solvent-extracted corn stover that was achieved implies that lignin is not the only major barrier for enzymatic hydrolysis. Modification of cellulose structure also should be accomplished to achieve a high degree of conversion. Enzymatic hydrolysis in the agitated bead system increased the rate and extent of conversion of corn stover substantially compared to systems without beads.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260290506
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  • 16
    Electronic Resource
    Electronic Resource
    External-circulation-loop airlift bioreactors: Study of the liquid circulating velocity in highly viscous non-Newtonian liquids (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 301-312 
    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 order to obtain further information on the behavior and optimal design of external-circulation-loop airlift (ECL-AL) bioreactors, the liquid circulating velocity, gas holdup and average bubble diameter in the downcomer were studied using highly viscous pseudoplastic solutions of various types of CMC. A few comparative measurements also were made using a viscous Newtonian aqueous sucrose solution. For the liquid velocity measurements, an ultrasonic flow meter (Doppler frequency shift principle) was applied for the first time to the gas/non-Newtonian liquid dispersion in downward flow and satisfactory results were obtained. For viscous liquids, the circulating liquid velocity in the riser section of an ECL-AL (uLR) is shown to be dependent mainly on the downcomer-to-riser cross-sectional area ratio (Ad/Ar), the effective viscosity (ηeff) and the gas superficial velocity (uGR) as described by the following equation \documentclass{article}\pagestyle{empty}\begin{document}$$ u_{LR} = 0.23u_{GR}^{0.32} (A_d /A_r)^{0.97} \eta _{eff}^{ - 0.39} $$\end{document} The circulating liquid velocity exerts opposing effects on the mass transfer and liquid-phase mixing performances of ECL-AL fermentors. Therefore, it is proposed that the optimum operating conditions for a given fermentation may be best achieved by means of independently regulating the circulating liquid velocity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320307
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  • 17
    Electronic Resource
    Electronic Resource
    Comments on the communication: On the calculation of shear rate and apparent viscosity in airlift and bubble column bioreactors (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 212-216 
    Details
    ISSN: 0006-3592
    Keywords: airlift bioreactor ; shera rates in reactors ; hydrodynamics ; non-Newtonian fluids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The determination of the shear rate in bubble column and airlift bioreactors is an important question from both the perspective of cell damage and the correlation of hydrodynamic parameters in non-Newtonian fluids in these contractors. In the context of correlating hydrodynamic parameters in non-Newtonian fluids, a common approach involves assuming that there exists an average shear rate in the column that is proportional to the superficial gas velocity. This average shear rate is then used to evaluate an effective viscosity of the non-Newtonian fluid that is subsequently used to quantify the fluid's rheological behavior in correlation. Contrary to a recent communication, this report illustrates that this approach, which has mainly been applied to bubble columns, can also be applied to external loop airlift contractors, replacing the superficial gas velocity by the superficial gas velocity by the superficial gas velocity supplied to the riser of the contractor. This extension is based upon consideration of the relevant characteristic velocity in the active zone (i.e., the riser section) of the reactor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380214
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  • 18
    Electronic Resource
    Electronic Resource
    Chemical and enzymic pretreatment of corn stover to produce soluble fermentation substrates (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 362-368 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Corn stover was pretreated with various chemical agents, including sodium hydroxide, sulfuric acid, ethylenediamine, n-butylamine (either alone or in solution with methanol), and acetonitrile or ethanol containing hydrochloric acid. Of these chemicals, n-butylamine was the best reagent for pretreatment of corn stover, considering the degree of loss of total carbohydrate, delignification, cumulative weight loss, cumulative yield of reducing sugars per original total carbohydrate, and the potential ease of recovery and reuse of reagent. In comparison to the other reagents tested, n-butylamine (n-BA) selectively delignified corn stover. The best conditions were as follows: a 12-h presoak of about a 155 g dry wt/L slurry (1 mm average particle size) in 100% n-BA at room temperature, followed by 30 min of refluxing (86.5°C) with 40% (w/w) n-BA-distilled water solution. The cumulative yield of reducing sugars after enzymic hydrolysis was 44.5% of the original total carbohydrate and the cumulative total weight loss (dry basis) was 59%. Degradative loss of total carbohydrate during pretreatment was not detected.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270322
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  • 19
    Electronic Resource
    Electronic Resource
    Gas holdup and overall volumetric oxygen transfer coefficient in airlift contactors (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 369-381 
    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 two major types of airlift contactors, concentric-tube and external-loop, were investigated for their gas holdup (riser and downcomer) and overall mass transfer characteristics. Results obtained in batch charges of tap water and 0.15 kmol/m3 NaCl solution are reported for external-loop airlift contactors having downcomer-to-riser cross-sectional area ratios, Ad/Ar, ranging from 0.11 ≤ Ad/Ar ≤ 0.69 and for concentric-tube types in the range 0.13 ≤ Ad/Ar ≤ 0.56.The results are compared and contrasted for the two types of airlift contactors and also with corresponding results obtained in a bubble column (Ad/Ar = 0). Both the riser gas holdup, (εG)r, and the overall volumetric mass transfer coefficient, (KLaD)T, were found to increase with increasing gas superficial velocity and the corresponding specific gassing power input, (PG/VD)T. However, at a specified power input both (εG)r and (KLaD)T decreased with increasing Ad/Ar due to a resultant increase in circulating liquid velocity. Unifying generalized correlations for both types of airlift contactors are given for both (εG)r and (KLaD)T. These correlations are expected to be applicable as well to continuous-liquid flow bubble columns at comparable liquid velocities.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270323
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  • 20
    Electronic Resource
    Electronic Resource
    Induction of T4 DNA ligase in a recombinant strain of Escherichia coli (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 991-998 
    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 kinetics of cell growth and foreign protein production, as well as factors affecting protein stability, were studied and optimized in batch and fed-batch fermentations of a recombinant strain of Escherichia coli. The pL promoter from bacteriophage lambda under the control of a temperature-sensitive cl represser, with the entire construct integrated into the E. coli chromosome through the use of a defective bacteriophage lambda lysogen, was used to direct the synthesis of T4 DNA ligase. The biphasic fermentations consisted of a primary growth phase at 30°C followed by an induction phase which was initiated by shifting the temperature to 42°C. In the fed-batch fermentations, additional nutrients were added at the time of initiating induction. Maintenance of sufficiently high concentrations of the organic substrates (glucose and casamino acids) during the induction phase was required for continued cell growth at 42°C. Such growth was essential for T4 DNA ligase formation and in vivo stability. Hence, fed-batch fermentations produced the highest yield of the foreign protein Commensurate with providing lower total amounts of substrates. In such cases, high cell densities (6 g dry wt/L) with substantial intracellular levels of T4 DNA ligase (4.6% total cellular protein, or 2.7% of the dry biomass) were achieved.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330808
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