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  • Biochemistry and Biotechnology  (722)
  • 1995-1999
  • 1980-1984  (722)
  • 1975-1979
  • 1983  (404)
  • 1981  (318)
Collection
Publisher
Years
  • 1995-1999
  • 1980-1984  (722)
  • 1975-1979
Year
  • 101
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1611-1622 
    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 method has been developed for the measurement of overall volumetric mass transfer coefficient (KLa) in gas-liquid-solid systems. This method is based on the examination of gas phase dynamics in a three-phase contactor and consists of measuring continuously the response of the outlet gas composition to a step input change of CO2 in the inlet gas stream. The advantages and limitations of the new method are presented and its sensitivity is discussed on the basis of model predictions. Preliminary results on the implementation of the CO2 method are also reported. Experimental data obtained in a nonviscous electrolyte solution show that the proposed method compares favorably with the conventional dissolved oxygen technique, provided that a correction is made to take account of the difference in diffusivity of oxygen and carbon dioxide.
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  • 102
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    Biotechnology and Bioengineering 23 (1981), S. 1623-1637 
    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 pH on the budding cycle of a respiration-deficient mutant of Saccharomyces cerevisiae were investigation by monitoring the time course of bud development on single cells. The volume of each bud was measured at various time intervals between the inception of its development and inception of development of the next bud on the mother cell. A previous report that the budding cycle consisted of two phases (a rapid-growth phase and a slow-growth phase) was confirmed. With increase in pH from 3.8 to 6.0 the budding cycle shortened as a result of both increase in rate of the rapid-growth phase and decrease in the duration of the slow-growth phase. Although further increase in pH to 7.4 further increased the rate of the rapid-growth phase, the budding cycle lengthened as a result of an increase in time lag and increase in duration of the slow-growth phase. The growth rate, in terms of bud volume, conformed with the expression: (1/V)(dV/dτ) = ξ exp(-V/η), where the values of ξ and η were dependent on pH. The cell volume distribution in a batch culture was compared with the cell volume distribution calculated from the growth curve of a single bud. Similarities in the curves suggested that the growth pattern of a whole culture reflected the growth pattern of a single cell.
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  • 103
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1573-1590 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cellulolytic activity of crude enzyme preparations from different cellulolytic fungi (namely Trichoderma viride, Trichoderma Koningii, Fusarium solani, Sporotrichum pulverulentum, Sporotrichum thermophile) was assayed comparatively with several common analytical procedures described in the literature. The investigation was carried out with the objective of evaluating, with raw culture filtrates, the different cellulase tests in relation to their specificity for endo- and exo-cellulase action as well as to allow comparisons to be made between results from different research groups using different methods. (1)Cellulase activity was tested viscometrically as well as chemically (determination of reducing end groups) with different carboxymethylcelluloses as substrates. Essentially constant ratios between both kinds of activities were obtained, indicating that they are directly related. Nevertheless, international units of activity, calculated from viscometric measurements (glycosidic bonds broken per unit time) were considerably lower than international units deduced from the increase in reducing power (glucose equivalents liberated per unit time), this discrepancy most likely accounted for by the predominant influence of the exo-cellulase component in cellulase tests based on the determination of reducing eng groups. (2) By estimating cellulase activity with insoluble cellulosic substrates no direct relationship could be established with the above-described activities except in the case where the cellulose was amorphous. The ratio profile between activities thus obtained and endo-cellulase activities determined viscometrically shows that some enzyme preparations (such as those from both Trichoderma sp.) are clearly more active than others against crystalline cellulose reflecting quantitative differences in enzyme composition. Nevertheless, for a biological understanding of cellulolysis. analytical procedures using crystalline celluloses are not adequate for specifically monitoring exo-cellulase activity in crude enzyme solutions for essentially two reasons: (a) they are not sufficiently sensitive to detect small changes in enzyme activity during the early phase of growth, and (b) exo-cellulase activity in crude enzyme solutions also depends on the endo-cellulase activity present.
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  • 104
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1653-1659 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein production by Aspergillus terreus GN1 grown on 1.0% alkali-treated bagasse was studied under various cultural conditions. The maximum biomass protein content of 20.1% and protein recovery of 11.2% was obtained with an initial pH of 4.0, with 1/5 (v/v) inoculum in continuously shaken cultures grown for seven days. Protein content of the alkali-treated bagasse was 3.0%. Highest crude protein percent also corresponded with highest carboxymethyl cellulase and filter paper enzyme activities.
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  • 105
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    Biotechnology and Bioengineering 23 (1981), S. 1639-1651 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several modes of interaction are demonstrated and modeled in the Proteus vulgaris-Saccharomyces cerevisiae system, in particular, commensalism (citrate present. glucose limiting, the nicotinic acid required by the bacterium supplied by the yeast), and commensalism and competition [citrate absent, both organisms compete for the same limiting carbon source (glucose) and the yeast supplies the nicotinic acid for the bacterium]. By varying the medium component concentrations, competition (citrate absent, glucose limiting, nicotinic acid not limiting), mutualism (citrate excess, glucose limiting, nicotinic acid absent), and neutralism (citrate limiting, glucose limiting, and nicotinic acid excess) could also be created. Kinetic models for commensalism and commensalism plus competition were developed to describe cell growth, substrate utilization, and nicotinic acid production. Good agreement with experiment was obtained for the commensalism case.
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  • 106
    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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  • 107
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    Biotechnology and Bioengineering 23 (1981), S. 1669-1674 
    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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  • 108
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    Biotechnology and Bioengineering 23 (1981) 
    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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  • 109
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    Biotechnology and Bioengineering 23 (1981), S. 1675-1681 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The procedure for isolation of D-phenylglycine from its racemic mixture by enzymatic hydrolysis of L-enantiomer of N-acetyl-D,L-phenylglycine is described. For this hydrolysis. aminoacylase from Micrococcus agilis immobilized by sorption of DEAE-cellulose was applied. As is also shown, the course of enzymatic reaction can be directly controlled by spectrophotometric method.
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  • 110
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    Biotechnology and Bioengineering 23 (1981), S. 1683-1702 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The oxidation of ammonium ion to nitrite and nitrate ion (nitrification) has been studied in a laboratory scale fluidized sand bed reactor with attached microbial growth. The undefined population of Nitrobacteracea organisms were immobilized on the sand particles by natural attachment after 2-3 months of adaptation. General balance equations have been formulated for a recycle reactor and oxygenation tank system. Kinetic experiments in the reactor and in a microrespirometer have been analyzed in terms of double Michaelis-Menten rate expression for the nitrogenous reactants and dissolved oxygen. Dynamic simulation of the batch integral reactor system was used to establish the error in the kinetic constant which arose due to assuming differential behavior. Design guidelines have been developed for the oxygen requirements in terms of oxygen transfer coefficients, oxygen enrichment, and liquid recycle rate.
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  • 111
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    Biotechnology and Bioengineering 23 (1981), S. 1703-1719 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous hydrolysis of triglyceride in organic solvent systems using Rhizopus arrhizus mycelia as a source of insolubilized lipase has been studied in packed-bed and stirred-tank reactors. Typically a packed bed reactor containing 1 g of mycelia fed at 1 mL/min with a solution of 2.5% (w/v) olive oil in di-isopropyl ether gave a fatty acid yield of 45% at 30°C. The optimum water concentration was found to be 0.17% (w/v) except under conditions of high oil feed concentration and high yield where no optimum was established. No temperature optimum was observed over the range 20-55°C. Calculated activation energies of 13-20 kJ/mol, depending on temperature, were lower, while Km(app) values of 0.1-0.3M were higher than those for hydrolysis in conventional aqueous emulsion systems. No evidence of any significant diffusional limitation, which could account for these values, was obtained. The mycelia showed a loss of activity of 0.6-1.0%h at 30°C. The packed bed proved markedly superior to the stirred tank for this system.
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  • 112
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    Biotechnology and Bioengineering 23 (1981), S. 1721-1734 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lactate dehydrogenase (LDH) was adsorbed on low-(γ, η) and high -(θ, α) temperature forms of alumina. θ-Al2O3 exhibited the greatest adsorption ability. The maximum adsorption value was 30 mg LDH/g of a carrier. The conditions for irreversible adsorption have been determined. An adsorption isotherm on θ-Al2O3 for pH 6.0 has been obtained; the LDHads surface area and the carrier surface portion accessible to the enzyme molecules have been calculated. The reaction kinetic parameter were determined by taking into account the reaction proceeding in the intradiffusional region. The specific catalytic activity (Aspec) of LDHads at small surface coverage of θ-Al2O3 is five times less than Aspec of the native enzyme and KMimm with respect to NADH exceeds KMnat by two orders or magnitude. The is evidence for a strong LDH-Al2O3 interaction and a considerable deformation of the enzyme globule. Aspec and KM decrease as the amount of the enzyme attached to the carrier increases. Due to adsorption. LDH becomes thermostable and durable. The LDHads samples conserve 20-40% of their activity at room temperature during a year.
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  • 113
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    Biotechnology and Bioengineering 23 (1981), S. 1735-1762 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model for the aerobic growth of Saccharomyces cerevisiae in both batch and continuous culture is described. It was based on the experimental observation that the respiratory capacity of organism may become saturated and exhibit a maximum specific oxygen uptake rate after suitable adaptation. This experimental observation led to the possibility that transport into and out of the mitochondrion was of major importance in the overall metabolism of S. cerevisiae and was subject to long-term adaptation. Consistent with this observation a distributed model was proposed which. as its basis, assumed the control of repression or inhibition of the uptake rates of other substrates. No other regulation of fermentation and respiration was assumed. The model provided a suitable structure allowing precise quantification of the changes in rate and stoichiometry of energy production. The model clearly indicated that growth under the wide range of experimental conditions reported could not be predicted using constant values for the maximum specific respiratory rate of constant values of YATP (g biomass/mol ATP) and PO ratio of (mol ATP/atom oxygen). The causes of the variation in the respiratory rate were not determined and it was concluded that a more detailed analysis (reported subsequently) was required. The variation of YATP and PO ratio with specific growth rate implied that the efficiency of ATP generation or ATP utilization decreased with increasing specific growth rate. It was concluded that it was not possible to quantify the individual effect of YATP and PO ratio until independent means for their reliable estimation is available.
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  • 114
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    Biotechnology and Bioengineering 23 (1981), S. 1961-1976 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A pulse of substrate solution was applied to an immobilized-enzyme column, in which the substrate was then converted by reversible or consecutive reactions. Immobilized glucose isomerase was used for the reversible reaction, and immobilized invertase and glucose oxidase for the consecutive reactions. The elution profiles of substrate and product were determined experimentally. These profiles were in good agreement with the ones predicted theoretically. The effect of some parameters on the elution profiles for reversible and consecutive reactions is discussed.
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  • 115
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    Biotechnology and Bioengineering 23 (1981), S. 1977-1989 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A small reactor of immobilized papain was used to gain some knowledge about the effect of immobilization upon the reactivity of the enzyme towards one substrate and various types of inhibitors. A buffer solution containing benzoyl-arginine ethyl ester as substrate was run through a small column of papain immobilized by attachment to agarose beads. The pH of the effluent was measured continuously and provided the data used to calculate the substrate conversion during passage through the reactor. The operation of the system was checked by determining the substrate conversion as a function of flow rate. It proved to operate as theory demanded. The rate and extent of inhibition were measured after addition of various inhibitors to the buffer-substrate solution. The following quantities of immobilized papain were found to be equal within ±20% to those of the free enzyme in solution: the overall activity, the Km of benzoyl-arginine ethyl ester, the Ki of the competitive inhibitor benzoylamino-acetonitrile, the rate of inactivation by chloroacetic acid and by chloroacetamide, the rate of activation by cysteine of the mixed disulfide of papain and cysteine, and the rate of spontaneous reactivation of the KCNO-papain adduct. The inactivation by KCNO proved to be strongly pH dependent. This may explain why the rate of the latter reaction is only 66% of the rate with free enzyme. It is concluded that the rates and equilibrium constants measured in the present reactor system are within ±20% of the values of the dissolved enzyme, provided that the reactions are not strongly pH dependent. Calculation showed there was no diffusion limitation.
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  • 116
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    Biotechnology and Bioengineering 23 (1981), S. 2001-2008 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments are described in which municipal wastewater is submitted to reverse osmosis. During a test period of two months a tubular apparatus, operated batchwise, maintained its original flux and rejection, the permeate being of good quality as a raw material for drinking water. The wastewater was concentrated 7.7 times. Continuous anaerobic digestion of the brine removed over 90% of the BOD evolving the expected amount of methane. The overall process is considered in its context of environmental and energetic aspects and is compared with a conventional treatment. This reveals clear perspectives for practical application in urban areas.
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  • 117
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    Biotechnology and Bioengineering 23 (1981), S. 2009-2026 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Culture filtrates from three mutant strains of Trichoderma reesei grown on lactose and on cellulose were compared under use conditions on four cellulose substrates. Cellulose culture filtrates contained five to six times as much cellulase as lactose culture filtrates. Unconcentrated cellulose culture filtrates produced up to 10% sugar solutions from 15% cellulose in 24 h. Specific activity in enzyme assays and efficiency in saccharification tests were low for enzymes from all the mutants. Over a wide range the percent saccharification of a substrate in a given times was directly proportional to the logarithm of the ratio of initial concentrations of enzyme and substrate. As a result of this, dilute enzyme is more efficient than concentrated enzyme, but if high sugar concentrations are desired, very large quantities of enzyme are required. Since the slopes of these plots varied, the relative activity of cellulase on different substrates may be affected by enzyme concentration.
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  • 118
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    Biotechnology and Bioengineering 23 (1981), S. 2105-2116 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Spent sulfite liquor (SSL), a waste product of the paper pulping industry, is produced at a rate of 1 ton (dry basis) per ton of pulp. The sugar content of SSL is about 30 g/L. To reduce the biological oxygen demand (BOD) of SSL before disposal, torula yeast (Candida utilis) is produced by a continuous culture process, the productivity of which is limited by sugar concentration and cell growth rate. To increase productivity, a recycle system has been designed and tested. Cells were sedimented continuously with a flocculating agent (bentonite) before being recycled to the fermentor. A bentonite concentration of 0.02 g/g cell was required. A computer monitoring system based on material balancing techniques was developed to monitor and control the recycle system. With this computer system, productivity was raised to 6.1 g/L h, with cell concentration up to 65 g/L in the recycle stream and 24 g/L in the fermentor. This represents a productivity increase of 150% over continuous culture with no recycle.
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  • 119
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    Biotechnology and Bioengineering 23 (1981), S. 2137-2143 
    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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  • 120
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    Biotechnology and Bioengineering 23 (1981), S. 2145-2147 
    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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  • 121
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    Biotechnology and Bioengineering 23 (1981), S. 2117-2135 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Despite the increasing importance of airlift fermentors, very little published information is available on how the geometric configurations of the draft tubes and the air-sparging system affect the mixing and oxygen transfer characteristics of the fermentor. A 14-L air-lift fermentor was designed and build with a fixed liquid height to diameter ratio of 1.5 utilizing four equally spaced air jets at the bottom. Two jet orifice sizes were used, 1.27 and 3.81 mm i.d., and for each jet size the following four geometric configurations were used: Single inner concentric draft tube, single outer concentric draft tube, two concentric draft tubes, and no draft tubes where the fermentor was operated as a shallow bubble column. It was found that the presence of draft tubes stabilized liquid circulation patterns and gave systemically higher mixing times than those obtained in the absence of draft tubes. In addition, the double draft tube geometry resulted in higher mixing times than the single draft tubes. For the power unit volume range 20 to about 250 W/m3 the larger 3.81-mm orifices gave systemically higher kLa values than the smaller 1.27-mm i.d. orifices. At 200 W/m3 the use of a single outer draft tube with the 3.81-mm orifices resulted in 94% increase in kLa values over that obtained with no draft tubes. However, the effect of draft tube geometry on kLa values when the 1.27-mm orifices were used was not significant. The air bubble formation characteristics at the jet orifices were found to be different, which reflected the differences observed in mass transfer and mixing characteristics. The power economy for oxygen transfer was found to be depend strongly on the orifice size and less on the geometric configuration of draft tubes.
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  • 122
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    Biotechnology and Bioengineering 23 (1981), S. 2149-2149 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 123
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    Biotechnology and Bioengineering 23 (1981), S. 2151-2159 
    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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  • 124
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    Biotechnology and Bioengineering 23 (1981), S. 2161-2165 
    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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  • 125
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    Biotechnology and Bioengineering 23 (1981), S. 2171-2172 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 126
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    Biotechnology and Bioengineering 23 (1981) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 127
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    Biotechnology and Bioengineering 23 (1981), S. 2173-2183 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been shown that resting cells of Agrobacterium radiobacter catalyze a sequence of two stereospecific hydrolytic reactions leading to the complete transformation of racemic hydantoins to D-amino acids. This report describes some properties of this new biocatalyst and its potential application for the production of some D-amino acids, which are used as intermediates in the preparation of semisynthetic penicillin and cephalosporins.
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  • 128
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growth rates and amylase production rates were determined for the yeast Saccharomycopsis fibuligera grown on a simulated potato processing waste in a continuous-stirred-tank fermentor. S. fibuligera formed large multicellular flocs in the fermentor, and cell growth was reduced at low dilution rates because of mass-transfer resistance. The average Thiele modulus, which is the measure of extent of substrate diffusion, had a value ranging from φav = 2.2 for D = 0.10 to 0.3 for D = 0.40. Growth rates were described by the Monod equation modified to include mass-transfer effects. This modified Monod equation was used to predict growth rates from measured floc-size distribution. Experimentally determined growth rates were in close agreement with these predicted values.
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  • 129
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    Biotechnology and Bioengineering 25 (1983), S. 281-299 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The potential of continuous isopropanol-butanol-ethanol (IBE) fermentation by Ca-alginate-immobilized Clostridium beijerinckii cells in a continuous stirred-tank reactor is investigated. A mathematical model is presented to describe steady-state reactor performance. It appeared to be possible to use the biocatalyst particles repeatedly for successive fermentations (at least three times for a total duration of two months). Reactor productivity was 6-16 times higher than that of a batch fermentation (free cells), while the solvents yield was also increased. Measurements of substrate, product, and biomass concentrations were only partially in agreement with the model; however, a solid basis for further technological developement of the process has been laid.
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  • 130
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    Biotechnology and Bioengineering 25 (1983), S. 341-349 
    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 sodium bicarbonate concentration, population density, and temperature on the maintenance of an outdoor monoculture of the cyanobacterium Spirulina platensis were studied. A clear response by Spirulina to the concentration of bicarbonate was evident, with 0.2M bicarbonate representing the lowest concentration in which a monoculture could be maintained. When the temperatures fell during the winter period to some 20-25°C below the optimum for Spirulina, Chlorella sp. gradually increased and became the dominant species in the culture. Raising the temperature by covering the pond with transparent polyethylene resulted in a sharp decline in the population of Chlorella, and a gradual resumption of species dominance by Spirulina. In winter, there was an inverse relationship in the pond between the population density of Spirulina and the extent of contamination by Chlorella sp.; but no such effect was observed under field conditions at temperatures higher than 25°C.
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  • 131
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    Biotechnology and Bioengineering 25 (1983), S. 403-416 
    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 approach was developed to determine the half-saturation coefficient for dissolved oxygen (KDO) for three bacteria by maintaining a constant oxygen concentration in continuous culture, and employing a dynamic method to obtain the specific growth rate (μ) for each species. Measurement of μ at selected dissolved oxygen concentrations (DO) resulted in a typical Monod curve for a plot of μ vs. DO. Values for KDO and μmax were obtained from the Lineweaver-Burk reciprocal plot. The bacteria studied included representative strains of three microorganisms isolated in pure culture from poorly settling activated sludge: two filamentous microorganisms, Sphaerotilus natans and a second Sphaerotilus sp., and an unidentified floc-forming microorganism. The KDO values obtained for Sphaerotilus sp., S. natans, and the floc former were 0.014, 0.033, and 0.073 mg/L, respectively. Dual species competition experiments were conducted in continuous culture under low and high DO conditions. Successful growth competition by these microorganisms under DO-limiting conditions was consistent with experimentally determined KDO values. The finding of lower KDO values for the two Sphaerotilus species, compared to the floc former, confirmed the hypothesis that these filamentous microorganisms can outgrow floc-forming microorganisms in activated sludge when DO in the aeration basin is low.
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  • 132
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A working system for studying the effects of factors involved in the chemical nature of microcarriers on cell attachment, spreading, and growth was established. The system is based on polyacrylamide beads, prepared by the emulsion polymerization technique. Sieved beads of desirable mean diameter were derivatized to generate controlled amounts of primary and tertiary amino groups. These microcarriers were used for the propagation of four different cell strains: BHK, MDCK, CEF, and MRC-5. It was found that BHK cells attach and spread significantly faster on primary amino-derivatized beads than those with tertiary amino groups, and at a lower degree of charging. Cell yields of MDCK cells (with pronounced epithelial morphology) propagated on primary amino-derivatized beads were higher than that obtained for the tertiary amino-derivatized microcarriers. On the other hand, CEF and MRC-5 cells (with pronounced fibroblast morphology) achieved higher cell yields on the tertiary amino-derivatized microcarriers.
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  • 133
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    Biotechnology and Bioengineering 25 (1983), S. 559-568 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Potentiometric and amperometric measurements were made with microbial fuel cells containing E. coli or yeast as the anodic reducing agent and glucose as the oxidizable substrate. The catalytic effects of thionine and resorufin on the anode reaction were investigated. Results on the potentiometry, polarization, and coulombic output of the cells support a mediator-coupled mechanism for the transfer of electrons from the organism to the electrode in preference to a mechanism of “direct” electrochemical oxidation of glucose or its degradation products. Experiments with 14C-labeled glucose show that when a microbial fuel cell produces a current under load, exogenous glucose is metabolized to produce 14CO2. The Coulombic yields of the cells indicate a high degree of energy conversion in these systems.
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  • 134
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: With carrot cells grown in semicontinuous culture with phosphate as limiting nutrient. Dougall and Weyrauch (1980) found that the steady-state culture density was different at different dilution rates. They suggested that the yield constant for biomass was different at different dilution rates. Here the yield constant for biomass for PO43-, NH4+, Mg2+, and glucose-limited semicontinuous cultures has been measured directly at two dilution rates. The yield constants for PO43-, NH4+, and Mg2+ but not for glucose are different at the two dilution rates. The effects of pH and temperature on the biomass yield constant was measured to extend the number of system parameters examined. Biomass yield constant was changed little with change from 25 to 28°C or from pH 4.2 to pH 5.5. The steady-state levels of anthocyanin were also measured. The responses of anthocyanin levels to the system parameters are different to the biomass responses. The data suggest that at different values of each of the system parameters, the composition and metabolic activities of the cells at steady state in semicontinuous cultures are different.
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  • 135
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 136
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    Biotechnology and Bioengineering 25 (1983), S. 627-630 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 137
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    Biotechnology and Bioengineering 25 (1983), S. 271-280 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sorption characteristics of the cellulase system of Talaromyces emersonii on various cellulosic substrates were examined. Analysis of reaction mixture supernatants by electrophoresis and enzyme assay showed that all components of the cellulase system were rapidly adsorbed by cellulose and then gradually returned to the liquid phase as the hydrolysis of the substrate progressed. The extent of adsorption in the rapid phase was influenced by pH, temperature, the nature of the substrate, and its concentration.
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  • 138
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    Biotechnology and Bioengineering 25 (1983), S. 307-313 
    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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  • 139
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    Biotechnology and Bioengineering 25 (1983), S. 967-983 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In an effort to alter the filamentous morphology of Penicillium chrysogenum cells, a technique was developed to confine the growth of the mycelia to porous celite beads. The pore matrix of these beads was found to be very effective for entrapping mycelial cells and spores. The entrapped spores were used to initiate the fermentations in shake flask cultures. Significant increases in final cell densities were obtained in the confined cell cultures reaching up to 60 g/L cells. This is nearly double the cell concentration attainable in free cell cultures grown in the absence of beads. Cell loadings up to 0.55 g cells per bead were obtained in the confined cell cultures. In the later stages of the fermentations, the specific oxygen uptake rates in the confined cell cultures were found to decrease with respect to free cell cultures.
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  • 140
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    Biotechnology and Bioengineering 25 (1983), S. 1049-1055 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The construction and performance of an enzyme electrode is described which specifically detects lower primary aliphatic alcohols in aqueous solutions. The electrode consists of a commercial Clark-type oxygen electrode on which alcohol oxidase (E.C. 1.1.3.13) and catalase were immobilized. The decrease in electrode current is linearly proportional to ethanol concentrations between 1 and 25 ppm. The response of the electrode remains constant during 400 assays over a period of two weeks. The response time is between 1 and 25 min. Assembly of the electrode takes less than 1 h.
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  • 141
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    Biotechnology and Bioengineering 25 (1983), S. 1013-1025 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Escherichia coli B 10, which has high activity of tryptophan synthetase, was grown in a 50-L batch culture in order to determine in which growth phase the cells have the highest specific tryptophan productivity. Accordingly, whole cells of the stationary phase were used for immobilization in polyacrylamide beads. After immobilization, these immobilized cells had 56% activity of tryptophan synthetase compared with that of free cells. First, the properties of immobilized cells were investigated. Next, discontinuous productions of L-tryptophan were carried out by using immobilized cells. In discontinuous production of L-tryptophan by the batch, the activity remaining of immobilized cells was 76-79% after 30 times batchwise use. In continuous production of L-tryptophan with a continuous stirred tank reactor (CSTR), the activity remaining of the immobilized cells was 80% after continuous use for 50 days. The maximum productivity of L-tryptophan in this CSTR system was 0.12 g tryptophan L-1 h-1.
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  • 142
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    Biotechnology and Bioengineering 25 (1983), S. 1095-1107 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Exomaltohexaohydrolase (E.C.3.2.1.98) was immobilized by radiocopolymerization of some synthetic monomers which were mixed in various combinations. Irradiation was carried out while the mixture of monomers and enzymes was frozen in petroleum ether-dry-ice bath. Recovery of the immobilized enzyme was 44-75%.The optimum pH of the enzyme slightly shifted to the acidic side. The pH stability was improved remarkably by immobilization. The enzyme was stable retaining more than 90% of its original activity in the range pH 4-11. The optimum reaction temperature of the enzyme increased about 2°C. Heat stability was also improved by immobilization, and that the enzyme retained about 40% of its original activity after treatment at 75°C for 15 min. The immobilized enzyme was stable to the repeated use of 20 cycles. The Km value of the enzyme for short-chain amylose was almost the same as that of native enzyme. When soluble starch was used as the substrate, the Km, value of the enzyme was three times as large as that of native enzyme. Effects of various metal ions and inhibitors on the immobilized enzyme were also studied compared to the native enzyme.
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  • 143
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    Biotechnology and Bioengineering 25 (1983), S. 1169-1173 
    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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  • 144
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    Biotechnology and Bioengineering 25 (1983) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 145
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    Biotechnology and Bioengineering 25 (1983), S. 1215-1221 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of cartridge air filters for process air sterilization in commercial fermentation has proliferated in recent years. Sterile air cartridge filter performance is discussed. The use of dispersed oil particle (DOP) tests for in situ integrity testing is described and discussed.
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  • 146
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    Biotechnology and Bioengineering 25 (1983), S. 713-724 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Styrene-methacrylic acid copolymers of varying combinations crosslinked with p-DVB (1-2%) and porous structure were synthesized to be used as carriers in trypsin immobilization. The styrene-methacrylic acid copolymers containing free carboxy groups were activated by conversion into the mixed carbonic anhydride with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) at pH 4.0. The degree of activation of copolymers were determined from the amount of p-aminobenzoic acid each could bind. The activated copolymers were incubated with trypsin in phosphate buffer (pH 8.0) at 4°C for 24 h. The optimum conditions for enzymatic activity measurements determined and the activity tests were carried out in 1.5 × 10-2M CaCl2 solution (pH 8.0) at 0.05 ionic strength with a pH-stat instrument. The dependence of the activity of styrene-methacrylic acid (SMA)/trypsin derivatives to pH was investigated and it was observed that the optimum pH of the immobilized trypsin derivatives moved to the basic region compared to the native trypsin. It was found that as the ionic strength increased, the shift in the optimum pH decreased and the activity increased. The Michaelis constants for the SMA-trypsin derivatives were determined with aid of Lineweaver-Burk diagrams. The thermal, storage, and operational stabilities of SMA-trypsin derivatives were assessed. It was found that the above stabilities for all the immobilized trypsin derivatives were better than that for the native trypsin.
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  • 147
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    Biotechnology and Bioengineering 25 (1983), S. 1321-1330 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The free-fall terminal velocity of particles coated with a nitrifying biofilm was investigated. The drag force exerted by the liquid on a biocoated particle was found larger than that for an uncoated particle. A new formula for the drag coefficient was proposed. The wet density of biofilm was estimated as 1.14 g/cm3. A proposed modification of the Zaki-Richardson method was successfully used for calculations of the porosity of a fluidized bed.
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  • 148
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    Biotechnology and Bioengineering 25 (1983), S. 1393-1399 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the Iotech process, steam explosion of wood chips potentials hydrolysis of the cullulose by enzymes. A small portion of the exploded wood is used as substrate for the production of enzymes for hydrolysis of the remaining wood. Explosions conditions degrade some of the hemicellulose, creating factors (probably related to furfural) that impair enzymatic hydrolysis and destablized the cellulases. Fortunately, simple washing with water paremits more rapid hydrolysis while enzyme stability is greatly improved. Enzymes can be recovered from the hydrolysis residue by adjusting the pH to neutrality, and additional enzymes from hydrolysis filtrate can be adsorbed on fresh exploded wood en route to hydrolysis. A simple mass balance calculation shows proportions of various activities in a mix of fresh and recycled enzymes.
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  • 149
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    Biotechnology and Bioengineering 25 (1983) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 150
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    Biotechnology and Bioengineering 25 (1983), S. 1441-1452 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microbiological transformation of benzaldehyde accomplished by the fungus Rhodotorula mucilaginosa immobilized in the ultrafiltration cell was studied. A polysulfone membrane formed on a sintered PVC support was used for the separation of the transformation product from the cellular material. Kinetic investigations have led to results which are typical of continuously fed stirred tank reactors (CFSTR) - the value of the maximum reaction rate (Vmax) and apparent Michaelis constant (K′m) are practically independent of the substrate retention time (calculated in terms of the flow intensity value). A strong relationship was found to occur between Vmax and biomass concentration in the reactor. Study of the apparent enzyme stability shows that the decrease in the biocatalyst activity is chiefly caused by penetration of the cells through the membrane. The experimental results were approximated in terms of the adopted mathematical model. Based on this model, the half-lives (t1/2) of enzyme activities were determined. The t1/2 value varies from 35 to 82 days and depends both on the permeate flux through the membrane and on the separation properties of the membrane.
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  • 151
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    Biotechnology and Bioengineering 25 (1983), S. 1501-1508 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An amount of α-L-fucosidase from T. cornutus liver was copolymerized with glutaraldehyde using bovine serum albumin as the carrier protein. The properties of the native, the soluble enzyme polymer complex, and the insoluble enzyme polymer complex were studied and compared under various conditions of pH, temperature, substrate, and inhibitor concentration. Native α-L-fucosidase was heat labile and lost more than 85% of its activity when incubated at 55°C for 5 min. In contrast, under equivalent incubation conditions, both the soluble and the insoluble enzyme polymer complexes exhibited enhanced resistance to thermal inactivation and after 5 min lost only 65 and 40% of their original activity, respectively. Polymerzation also resulted in the shift of pH optima towards the acidic range, a decrease in activation energy and a change in the apparent Km values towards the p-nitrophenyl-α-L-fucopyranoside substrate.
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    Biotechnology and Bioengineering 25 (1983), S. 1509-1519 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cellulose fermentation studies were conducted with a thermotolerant strain of Aspergillus terreus. Batch cultivation of A. terreus using purified or complex cellulose showed that 80-88% of the available cellulose was utilized in 30-36 h with an average doubling time of 7.5-8.3 h. The protein content in the biomass ranged from 23 to 38%. Semicontinuous cultivation studies, in which 90% of the biomass was withdrawn at the end of growth cycle, indicated that 84% of added cellulose was utilized with the biomass containing 32% crude protein. No loss in cellulose consumption, growth rate, or protein production occurred through two growth cycles. Continuous cultivation of A. terreus showed that 78-84% cellulose consumption occurred over growth temperatures ranging from 35 to 45°C. Maximum specific growth rates (0.14 h-1) occurred at 40 and 45°C with a minimum doubling time of 4.9 h.
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    Biotechnology and Bioengineering 25 (1983), S. 1597-1612 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Evaporative loss of ethanol during batch alcoholic fermentation has been modelled, employing modern concepts of kinetics and stoichiometry and the best available phase equilibrium thermodynamic data. Theoretical results demonstrate that loss is proportional to the second power of the sugar concentration utilized and that the logarithm of loss is proportional to reciprocal absolute temperature. Good agreement is demonstrated among the theory, the numerical model, and the literature results. A master correlation for predicting ethanol loss is presented.
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    Biotechnology and Bioengineering 25 (1983), S. 1655-1660 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Biotechnology and Bioengineering 25 (1983), S. 1677-1678 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Biotechnology and Bioengineering 25 (1983), S. 1693-1700 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The efficiency of lipid synthesis by ethanol-grown yeasts is characterized using the coefficient of the lipid energetic yield (η1). This coefficient is defined as the fraction of energy in an organic substrate that is converted to lipids. The advantages of η1 compared with the “fat coefficient” (Fs) as well as the biomass energetic yield (η) compared with Ys are discussed.
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    Biotechnology and Bioengineering 25 (1983), S. 1205-1214 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Top entering drives have become almost traditional for fermentor applications, however bottom entering drives have distinct features that merit consideration. The prinicipal advantages of bottom drives are delineated and design criteria discussed. Illustrations based on experience with several hundred fermentors ranging in power from fractional to 100 HP and in scale from 10 to 30,000 gallons are presented. Specific areas dealt with include configuration, alignment, seals, and shaft design.
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  • 158
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    Biotechnology and Bioengineering 25 (1983), S. 1237-1250 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In 1979, a minicomputer system was developed for Hoffmann-La Roche by ABEC, Inc. for the purpose of achieving on-line analysis and reporting of data from 16 70-L pilot-plant fermentors (New Brunswick Scientific Co.). The system consists of a PDP 11/60 computer with 96K core capacity, two RL01 disk drives, two RX01 floppy-disk drives, LA-36 DECwriter terminal, Tektronix CRT, and Versatec printer plotter. DEC, PDP, RSX, RL01, RX01, LA-36, and DECwriter are trademarks of Digital Equipment Corporation. The computer software comprises three distinct groups of programs. RSX-11M is a disk-based operating system that allows quick response to realtime events, such as process monitoring and data acquisition, while carrying out less time-dependent activities, such as program development and graphical output. The AIM (Biles, Inc.) system is used to acquire and convert the voltage signals produced by pilot-plant instrumentation into engineering units. Analysis and graphical output are executed by ABEC and Versatec supplied programs. The most beneficial task performed by the computer is the production of graphical output of a variety of measured and analyzed data. This has led to an increase in personnel productivity and design of more meaningful experiments. An ancillary function of the system is to pick up data logged by a PDP 11/03 computer from a remote fermentation production plant by means of a MODEM interfaced communication link. Production data are analyzed and presented in a form identical with pilot-plant data. The experience with the system is discussed in this article.
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    Biotechnology and Bioengineering 25 (1983), S. 1863-1871 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillium funiculosum produces a complete cellulase which brings about 97% hydrolysis of cotton and has high β-glucosidase, xylanase, laminarinase, and lichenase activities. This article deals with the effect of different pretreatments on the hydrolysis of sugarcane bagasse by P. funiculosum enzymes and the recovery of enzyme from the insoluble residues. Enzymic saccharification of bagasse pretreated with hot 1N NaOH followed by neutralization with HCI and steam treated under pressure (7 kg/cm2) gave 63 and 59% saccharification, respectively, in 48 h. Hemicellulose is not lost in these pretreatments. With a 30% slurry of steam-treated bagasse, a semisolid mass containing 14% sugar was obtained. A 90% recovery of CMCase, β-glucosidase, and filter paper activity from the hydrolysates was obtained under the following conditions: (1) maintaining the ratio of enzyme to substrate high by stepwise addition of substrate, (2) brief grinding of the residual substrate with glass powder, and (3) addition of 0.4% Tween-80 to the eluting buffer. The high recovery of cellulolytic enzymes indicates that the adsorption of these enzymes on cellulose is not irreversible.
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  • 160
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    Biotechnology and Bioengineering 25 (1983) 
    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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  • 161
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    Biotechnology and Bioengineering 25 (1983), S. 1947-1957 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A methodology has been developed for the quantitative assessments of the individual effects of precipitation and chelation of metal ions in an anaerobic digester.
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  • 162
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    Biotechnology and Bioengineering 25 (1983), S. 1973-1980 
    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 method of preparing a chitin-immobilized α-amylase and glucoamylase from the protease- and glycosidase-less Mutant HF-15 of Aspergillus awamori var. kawachi was developed and used for the production of high-glucose syrup. The glucoamylase was tightly bound onto chitin without the aid of a crosslinking agent because the enzyme contained a specific binding site for chitin. Continuous production of high glucose concentrate from a highly concentrated α-amylasetreated gelatinized starch substrate (about 45% total solids) was undertaken successfully with the use of a column-packed chitin-immobilized amylase. The activity of the column was stable for more than 20 days of continuous operation and the product was found to be only glucose with an average dextrose equivalent value of more than 97%. The final product showed no isomaltose or panose contamination, indicating that the immobilized amylase had no transglucosidation activity. The immobilized amylase was most active in the conversion of gelatinized starch to glucose at 55°C and pH 2.5 to 5.0. Drying the chitin-immobilized amylase resulted in the decrease of activity and shortening of storage life, whereas a storage life of up to 80 days was attained without affecting its original activity when kept under moist condition at 4°C.
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  • 163
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    Biotechnology and Bioengineering 23 (1981), S. 2779-2788 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cellobiase (CE 3.2.1.21) is a β-glucosidase which hydrolyzes cellobiose to glucose and is known to be subject to both product and substrate inhibition. This work report a model which combines both product and substrate inhibition effects for cellobiase isolated from a commercial preparation of Trichoderma viride from Miles Laboratories (Elkhart, IN). An integrated rate equation is presented which predicts the trends of time courses for hydrolyses of cellobiose a t concentrations ranging from 14.6-1416mM cellobiose. The constants used in the model (determined from initial rate data) are compared to those reported for cellobiase obtained from other sources of T. Viride. Most notable in this comparison is the apparently higher activity and reduced inhibition of this enzyme compared to other sources of cellobiase.
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  • 164
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    Biotechnology and Bioengineering 23 (1981), S. 2789-2802 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Multienzyme reaction systems with simultaneous coenzyme regeneration have been investigated in a continuously operated membrane reactor at bench scale. NAD(H) covalently bound to polyethylene glycol with a molecular weight of 104 [PEG-10,000-NAD(H)] was used as coenzyme. It could be retained in the membrane reactor together with the enzymes. L-leucine dehydrogenase (LEUDH) was used as catalyze for the reductive amination of α-ketoisocaproate (2-oxo-4-methylpentanoic acid) to L-leucine. Format dehydrogenease (FDH) was used for the regeneration of NADH. Kinetic experiments were carried out to obtain data which could be used in a kinetic model in order to predict the performance of an enzyme membrane reactor for the continuous production of L-leucine. The kinetic constants Vmax and Km of enzymes are all in the same range regardless of whether native NAD(H) or PEG-10,000-NAD(H) is used as coenzyme. L-leucine was produced continuously out of α-ketoisocaproate for 48 days; a maximal conversion of 99.7% was reached. The space-time yield was 324 mmol/L day (or 42.5 g/L day).
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  • 165
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    Biotechnology and Bioengineering 23 (1981), S. 2803-2813 
    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 article the filtration resistance of fungal (Penicillium) mycelia is shown to be quantitatively related to the morphology of the cells. On this basis, it was possible to determine the intracellular volume by simple filtration measurements. Since the dry weight of the cells can also be measured, a morphological variable-the “hyphae density” (dry weight hyphae/volume hyphae)-can be quantified. This variable typically is measured to have values in the range of 0.35-0.20 g/cm3; the lower values represent the final stages of the fermentation. It can be shown that this loss of cell material during fermentation is limited to cytoplasmic components, and that most (70%) of the components which disappear are proteins. Concurrent with and linearly related to this loss of proteins, the culture activity in terms of both cell maintenance energy (respiration activity) and penicillin synthesis also decreased. The hyphae density measured by filtration is therefore a direct measure of the metabolic potential of the organism.
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  • 166
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    Biotechnology and Bioengineering 25 (1983), S. 1083-1093 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of the extracellular nuclease secreted by Staphylococcus aureus (Foggi strain) was studied in a fermentor in an attempt to improve yield and allow large-scale production of the enzyme. In shake flask cultures, 600 units/mL of the enzyme were produced routinely. However, only 450 units/mL of the enzyme at best were obtained in a small-scale fermentor (3 L). The supplementation of the air supply to the fermentor with carbon dioxide [20% (v/v)] increased levels of enzyme in the culture medium to 770 units/mL. Subsequently, this result was reproduced in larger fermentors (10 and 150 L). The possible mechanisms of the effect of carbon dioxide upon the growth of Staphylococcus aureus (Foggi) and the production of the enzyme are discussed.
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  • 167
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    Biotechnology and Bioengineering 25 (1983), S. 1109-1126 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Direct anaerobic bioconversion of cellulosic substances into ethanol by Clostridium thermocellum ATCC 27405 has been carried out at 60°C and pH 7.0 (initial for 100 L) under continuous sparging of oxygen free nitrogen in a culture vessel. Raw bagasse, mild alkali-treated bagasse, and solka floc were used as substrates. The extent of conversion of raw bagasse (cellulose, 50%; hemicellulose, 25%; lignin, 19%) was observed as 52% (w/w) and 79% (w/w) in the case of mild alkali and steam-treated bagasse (cellulose, 72%; hemicellulose, 11%; lignin, 12%), respectively. Use of bagasse concentration above 10 g/L showed a decreased rate in ethanol production. An inoculum age between 28-30 h and cell mass content of 0.027-0.036 g/L (dry basis) were used. The results obtained with raw and pretreated bagasse have been compared with those of highly pure Solka Floc (hemicellulose, 10%). Studies on the product inhibition indicated a linear fall of the percent of survivors with time. An Arrhenius type correlation between the cell decay rate constant and the product concentration was predicted. Even at low levels, the inhibitory effects of products on cell viability, the specific growth rate, and extracellular cellulase enzyme were observed.
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  • 168
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    Biotechnology and Bioengineering 25 (1983), S. 1789-1800 
    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 suitable for large-scale isolation of β-galactosidase from a suspension of disintegrated E. coli cells has been developed. In an aqueous two-phase system consiting of PEG 6000 and potassium phosphate, all cell debris and the major part of the proteins and nucleic acids were partitioned to the denser salt phase. Seventy-five percent of the β-galactosidase was recovered in the lighter PEG phase, giving a purification ratio of about 12.
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  • 169
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    Biotechnology and Bioengineering 25 (1983), S. 1829-1839 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetics of the degradation of olive oil by an acclimated activated sludge were studied. Kinetic constants for the lipid removal from the mixed liquor and for that from the supernatant and for the hydrolysis step were evaluated using Michelis-Menten equations. The maximum specific reactions rates (vmax) and the saturation constants (Km) were vmax = 1.20 mg lipid mg-1 MLVSS day-1 and Km = 1290 mg/L for lipid removal from the mixed liquor; vmax = 1.54 mg lipid mg-1 MLVSS day-1 and Km = 801 mg/L for that from the supernatant; vmax = 1.57 mg olive oil mg-1 MLVSS day-1 and Km = 1750 mg/L for the hydrolysis of olive oil (where MLVSS refers to mixed liquor volatile suspended solids). The adsorption of olive oil by the activated sludge contributed to the lipid removal from the supernatant. The specific rate of this adsorption was also estimated. The hydrolysis, rather than the oxidation of free fatty acids, was the rate limiting step in the degradation of olive oil when the concentration of olive oil was lower than about 800 mg/L.
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  • 170
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    Biotechnology and Bioengineering 25 (1983), S. 1897-1904 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hydrogen photoproduction from water in Scenedesmus cells requires removal of oxygen by a reagent in contact with the algae. Both deoxyhemoglobin and deoxymyoglobin stimulated hydrogen production by reversible absorption of oxygen. Their effectiveness was greatly increased when other oxygen-combining reagents were present in a separate chamber with deoxyhemoglobin and deoxymyoglobin serving as reversible oxygen transfer agents.
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  • 171
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    Biotechnology and Bioengineering 25 (1983), S. 1295-1310 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flow cytometry is a fast and sensitive method that allows monitoring of different cellular parameters on large samples of a population. Protein distributons give relevant information on growth dynamics, since they are related to the age distribution and depend on the law of growth of the population and the law of protein accumulation during the cell cycle. We analyzed protein distributions to evaluate alternative growth models for the budding yeast Saccharomyces cerevisiae and to monitor the changes in population dynamics that result from environmental modifications; such an analysis could potentially give parameters useful in the control of biotechnological processes. Theoretical protein distributions (taking into account the unequal division of yeast cells and the exponential law of protein accumulation during a cell cycle) quantitatively fit experimental distributions, once appropriate variability sources are introduced. Best fits are obtained when the protein threshold required for bud emergence increases at each new generation of parent cells.
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  • 172
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    Biotechnology and Bioengineering 25 (1983), S. 1341-1357 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of biomass and β-D-galactosidase by the lactose-utilizing yeast Candida pseudotropicalis NCYC 744 in whey medium was studied. Apparent optimization of growth conditions and medium was done in continuous culture. Optimaql pH and temperature were 2.6 and 36-38°C, respectively, Limitations in Cu, Zn, and possbily Mn were detected in deproteinized whey medium. Additions of tryptophan estimulated growth of the yeast. Under optimal conditions in medium supplemented with excess tryptophan, Cu, Zn, and Mn the maximum values obtained: yeast concentration, 4.6 g/L; yeast productivity, 1.4 g/L h (at D = 0.35 h-1); enzyme volumetric productivity, 2100 U/L h (at D = 0.25 h-1); maintenance coefficient, 5-10 mg lactose/g cell h; saturation constant (Ks) for lactose, 4.76mM; maximum specific growth rate, (μmax), 0.47 h-1. No significant increase in specific enzyme activity (U/mg cell) was observed after medium optimiztion evidencing the importance of regulatory controls in enzyme synthesis.
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  • 173
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    Biotechnology and Bioengineering 25 (1983), S. 1401-1418 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general model of the transient behaviour of an oxygen probe is derived on more general assumptions than those previously considered. The present state of the art is shorly discussed in its relation to the newly derived equations: (1) the reducibility of the three-layer diffusional model to two-layer ones is discussed, and the two-layer model considering the membrane and the liquid film is verified experimentally, (2) experimental and theoretical treatments of transient probe characteristics determination are examined, and (3) the influence of chemical reactions of the first order as well as of zero order (microorgaganism respiration) in measured media on transientd probe characteristics is quantified.
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  • 174
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass production and carbohydrate reduction were determined for a two-stage continuous fermentation process with a simulated potato processing waste feed. The amylolytic yeast Saccharomycopsis fibuligera was grown in the first stage and a mixed culture of S. fibuligera and Candida utilis was maintained in the second stage. All conditions for the first and second stages were fixed except the flow of medium to the second stage was varied. Maximum biomass production occurred at a second stage dilution rate, D2, of 0.27 h -1. Carbohydrate reduction was inversely proportional to D2, between 0.10 and 0.35 h -1.
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  • 175
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    Biotechnology and Bioengineering 25 (1983), S. 2775-2776 
    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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  • 176
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    Biotechnology and Bioengineering 25 (1983), S. 2785-2788 
    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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  • 177
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    Biotechnology and Bioengineering 25 (1983), S. 2843-2853 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Axenic cultures of Rhodopseudomonas capsulata. Rhodospirillum rubrum, and Rhodomicrobium vannielii grown with glutamate as the nitrogen source converted lactate, acetate, and butyrate to H2 and CO2. Conversion rates ranged from 100 to 926 mL H2 Lr-1 day-1 (where Lr is the reactor contents), and efficiencies varied from 23 to 100% When grown with N2, conversion rates up to 760 mL H2 Lr-1 day-1 and efficiencies up to 100%were achieved. Upon aging, cultures appear to rapidly increase in hydrogen uptake activity and furthermore decrease in nitrogenase activity, both factors leading to a slowdown of hydrogen production. This was particularly the case for diazotrophically grown photobacteria.
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  • 178
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    Biotechnology and Bioengineering 25 (1983), S. 2873-2887 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The performance of a penicillin fermentation was assessed in a laboratory-scale bubble column fermentor, with mycelial growth confined to the pore matrix of celite beads. Final cell densities of 29 g/L and penicillin titres of 5.5 g/L were obtained in the confined cell cultures. In comparison, cultures of free mycelial cells grown in the absence of beads experienced dissolved oxygen limitations in the bubble column, giving only 17 g/L final cell concentrations with equally low penicillin titres of 2 g/L. The better performance of the confined cell cultures was attributed to enhanced gas liquid mass transfer rates, with mass transfer coefficients (kLa) two to three times higher than those determined in the free cell cultures. Furthermore, the confined cell cultures showed more efficient utilization of power input for mass transfer, providing up to 50% reduction in energy requirements for aeration.
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  • 179
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 180
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No. Abstract.
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  • 181
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    Biotechnology and Bioengineering 25 (1983), S. 1701-1723 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Results obtained in a 120 liter 2 m high UASB-reactor with raw domestic sewage and using a granular sugar beet waste cultivated seed sludge, reveal the feasibility of this type of anaerobic treatment for domestic sewage. Under dry weather conditions 65-85% COD reduction can be achieved at temperatures in the range of 8-20°C and at hydraulic loads as high as 2 m3 · m-3 · day-1. In the case of heavy rainfall the COD-reduction drops to 50-70% and occasionally, viz.at very low influent COD, even below 50%. The net methane production amounts to 7.1-7.3 m3 · PE-1 · year-1, and the excess sludge production ranges form 5.0-8.6 kg TS · PE-1 · year-1. Regarding the results obtained anaerobic treatment of raw sewage not only looks an attractive proposition for tropic areas but also for moderate climatic areas.
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  • 182
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    Biotechnology and Bioengineering 25 (1983), S. 1781-1788 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A high phosphate accumulating bacterium, Arthrobacter globiformis PAB-6, was grown in a chemostat under glucose-limitation. Two different growth patterns at steady state with various dilution rates were obtained. In one case, cells having a coccus shape tended to washout at a low dilution rate, 0.2 (h-1). In another, cells with a rod shape grew faster and gave a good steady-state growth at a dilution rate of 0.4. Such a close relationship between growth rate and cell morphology was found both in continuous and batch cultures. The amount of phosphate uptake per cell mass was almost constant irrespective of the dilution rate, but the rate of the uptake was maximum at about the dilution rate of 0.4. A clone of PAB-6 was isolated from the continuous culture with high dilution rate and had maximum specific growth rate of 0.7 in a simple glucosesalt medium.
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  • 183
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    Biotechnology and Bioengineering 25 (1983), S. 1841-1861 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A four-component, diffusion-reaction model with double Michaelis-Menten kinetics was used to describe the experimental data obtained from a laboratory biofilm, fluidized-bed nitrification reactor. Theory and experiment demonstrated that the stoichiometric ratio (3.5 mg O2/mg NH4+-N) can be employed as a criterion to determine whether the limiting substrate is oxygen or ammonia. For the present work, in the range of concentrations where limitation occurred, 4 mg/L NH4+-N and 14 mg/L O2, the ratio of oxygen to ammonia in the bulk liquid determined which substrate was penetration-limiting - O2 if 〈3.5 and NH4+ if 〉 3.5. Halforder kinetics with respect to the limiting substrate described the apparent overall rates. Simulations provided biofilm concentration profiles which demonstrated the role of the oxygen-ammonia ratio. Experiments indicated that, generally, high NO2- concentrations can be expected. These depend on the residence time, biofilm area, and oxygen concentration. This dependency was investigated with the model, as was the parametric sensitivity with respect to the saturation constants. Particularly important for the NO2- levels were the ratios of the saturation constants for oxygen.
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  • 184
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    Biotechnology and Bioengineering 25 (1983), S. 1905-1911 
    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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  • 185
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    Biotechnology and Bioengineering 25 (1983), S. 1981-1987 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The filtration characteristics of the penicillin broth can be monitored semicontinuously using an automatic filtration probe. This probe operates aseptically and the broth samples (filtrate and filter cake) are recycled to the fermentor after each filtration. The collected data - filtrate volume and filter cake volume versus filtration time - can be related to the total biomass concentration in the fermentor.
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  • 186
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    Biotechnology and Bioengineering 25 (1983), S. 1995-2006 
    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 method is presented for the treatment of gel-type supports, used for immobilizing microbial cells and enzymes, to obtain high mechanical strength. It is particularly useful for ethanol fermentation over gel beads containing immobilized viable cells, where the beads can be ruptured by gas production and the growth of cells within the gels. This method consists of treating agar or carrageenan gel with polyacrylamide to form a rigid support which retains the high catalytic activity characteristic of the untreated biocatalysts. The size and shape of the biocatalyst is unaffected by this treatment. The method involves the diffusion of acrylamide, N,N′-methylenebisacrylamide and β-dimethylaminopropionitrile (or N,N,N′,N′-tetramethyl-ethylenediamine) into the performed biocatalyst beads followed by the addition of an initiator to cause polymerization within the beads. Treated gels have been used for the continuous fermentation of glucose to ethanol in a packed column for over two months. During this operation, the gel beads maintained their rigidity, and the maximum productivity was as high as 50 g h-1 L-1 gel. There was no appreciable decay of cell activity.
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    Biotechnology and Bioengineering 25 (1983), S. 2085-2089 
    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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    Biotechnology and Bioengineering 25 (1983), S. 2091-2092 
    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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  • 189
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    Biotechnology and Bioengineering 25 (1983), S. 2103-2125 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a nonmixed environment, bacterial population growth can be influenced significantly by cell motility properties as well as by growth kinetic properties. Therefore, in a situation of competition between two bacterial populations for a single chemical nutrient in a nonmixed environment, the outcome may depend upon the respective cell motility properties. In this article, the authors have presented a simple mathematical model for competitive growth of two randomly motile (i.e., possessing no chemotactic behavior) populations in a finite nonmixed region. An understanding of the behavior of this model should provide insight into the behavior of a number of common microbial competition problems. Analysis of this model yields the following results: (1) There may be as many as three possible non-trivial steady-state (or long-time) configurations: when species 1 survives, species 2 dies out; when species 2 survives, species 1 dies out; and species 1 and species 2 coexist. (2) The coexistence state can exist even though one species possesses a smaller intrinsic growth rate constant at all nutrient concentrations, if that same species is sufficiently less motile than the other species. (3) In fact, the species with the smaller maximum specific growth rate may grow to a larger population than the other. (4) The possibility of coexistence can be decided essentially from the results for single population growth.
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  • 190
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    Biotechnology and Bioengineering 25 (1983), S. 2209-2219 
    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 immobilization technique has been developed. It involves immobilizing enzymes on a porous polytetrafluoroethylene membrane with a nonporous polyurethane coat by the use of an electrostatic force, i.e. the Coulomb force. The immobilized enzyme can be recovered by supplying a reversed electrical potential. The reaction characteristics of the immobilized amyloglucosidase were studied using maltose as a substrate. The Michaelis constant becomes larger than that of the native enzyme, and depends on the electrical potential gradient in the solution.
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  • 191
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    Biotechnology and Bioengineering 25 (1983), S. 2757-2773 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saturating wood particles with HCl gas under pressure was found to be an effective pretreatment prior to subjecting wood to dilute acid hydrolysis. Pretreament is necessary to release sugars from wood because of the tight lattice structure of cellulose. The HCl gas makes the cellulose more susceptible to subsequent acid hydrolysis and the glucose yield is doubled when dilute acid hydrolysis is preceded by HCl saturation at high pressure. The saturation was most effectively performed in a fluidized bed reactor, with pure HCl gas fluidizing an equal volume of ground wood plus inert particles. The fluidized bed effectively dissipated the large amount of heat released upon HCl absorption into the wood. Batch reaction times of 1 h at 315 psia gave glucose yields of 80° and xylose yields of 95° after dilute acid hydrolysis. A model was developed which proposed gas diffusing through the solid as limiting the reaction rate and this was found to effectively describe the HCl-wood reaction in the fluidized bed. The HCl was found to form a stable adduct with the lignin residue in the wood, in a ratio of 3.33 mole of lignin monomer. The adduct was broken upon the addition of water.
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  • 192
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    Biotechnology and Bioengineering 25 (1983), S. 2795-2800 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Absrtact.
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  • 193
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    Biotechnology and Bioengineering 25 (1983), S. 1959-1972 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The relative importance of the individual effects of precipitation and chelation of metal ions in anaerobic digestion is assessed. Experimentally determined soluble metal ion levels are compared with predicted levels obtained by using a previously described methodology.1 It is found that soluble metal complexes may increase the level of soluble metals in the presence of CO32- and S2- by a factor of up to 104. The formation of a soluble complex may increase or decrease the availability of the metal ion in question for microbial uptake. Two case studies are presented, one using a defined medium and one a complex medium. It is possible, in the case of the defined medium, to accurately predict the free metal ion concentration using the methodology previously developed.1 While the identification of the presence of natural chelating compounds in a complex medium is not routinely possible, the significant discrepancy between the measured level of the soluble metal ion Fe2+ and the calculated level in the case studies presented indicates that natural chelating compounds may play a vital role in providing available metal ions to the microorganisms of an anaerobic digester.
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  • 194
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    Biotechnology and Bioengineering 25 (1983), S. 2007-2023 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcohol fermentation was studied with an emphasis on the separation of cell growth and alcohol production stages. Experiments were conducted to establish the optimal conditions for alcohol production in batch fermentations and to simulate continuous fermentations with cell feeding at various stages. It was found that the glucose concentration should be kept under 10% (w/v), and the temperature should be between 40 and 42.5°C for maximum specific alcohol productivity. If the cell concentration is increased, a decrease in specific alcohol productivity is observed. Higher cell concentrations are needed for higher final alcohol concentrations. Among the cell feeding procedures into alcohol production stages, a cocurrent design was found to be better than recycle and countercurrent designs.
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  • 195
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    Biotechnology and Bioengineering 25 (1983), S. 2041-2053 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pure cellulose (Avicel) was hydrolyzed batchwise at 50°C and pH 4.8 by cellulase from Trichoderma viride (Meicelase CEP). Then the effects of the crystallinity of cellulose as well as the thermal deactivation and product (cellubiose and glucose) inhibition to cellulose on the hydrolysis rate were quantitatively investigated. While these factor had evidently retarded the enzymatic hydrolysis of cellulose to a significant extent, the hydrolysis rates observed could not be explained. For practical purposes, an empirical, simple rate expression was developed which included only one parameter: a overall rate retardation constant. This empirical rate expression held for the hydrolysis of at least two kind of cellulosic materials: Avicel and tissue paper.
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  • 196
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    Biotechnology and Bioengineering 25 (1983), S. 2067-2076 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alkali treatment of corn stover improves the avaliability of cellulose and hemicellulose for enzymatic attack. Treatments were carried out for 1 to 60 min at temperatures and NaOH concentrations ranging from 100 to 150°C and 0 to 2%, respectively. Solubilization of the stover and sugar production by enzymatic hydrolysis (Trichoderma viride cellulase) of the solid residue and the dissolved solids were used to measure the effect of caustic treatment. At 150°C and 2% NaOH concentration, 65% of the original stover was dissolved after 5 min and 52% saccharificatin (g sugar/g stover) of the residue and dissolved solids by enzymatic hydrolysis was achieved compared to 20% for untreated corn stover.
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  • 197
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    Biotechnology and Bioengineering 25 (1983), S. 2099-2101 
    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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  • 198
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    Biotechnology and Bioengineering 25 (1983), S. 2231-2242 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Whole cells of Escherichia coli containing the enzyme penicillinamidohydrolase EC 3.5.1.11 were immobilized on the surface of modified macroporous copolymers of glycidylmethacrylate with ethylenedimethacrylate and of copolymers of methacrylaldehyde (MA) with divinylbenzene (DVB) by means of glutaraldehyde. These polymeric carriers were modified before cell binding by using ammonia or polyamines, especially ethylenediamine and hexamethylenediamine (HMDA). The highest specific activity and the largest yield in cell immobilization were achieved with the macroporous copolymer of MA and DVB modified with HMDA. The material thus obtained was used in repeated conversions of benzylpenicillin to 6-aminopenicillanic acid in a stirred batch reactor.
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  • 199
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    Biotechnology and Bioengineering 25 (1983), S. 2271-2276 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 200
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    Biotechnology and Bioengineering 25 (1983), S. 2337-2346 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been observed experimentally that the biodegradation of 2,4-dichlorophenoxyacetate (2,4-D) is inhibited by the presence of glucose. However, this effect is masked by the fact that larger concentrations of active biomass are produced when glucose is available. The implication of such a “mixed” growth in a continuous flow system is that much higher dilution rates can be applied for an efficient chlorinated-organic removal when other conventional substrates are present. The mean cell residence time is reduced and the area of stability of the process is extended into higher dilution rates, as well as into higher influent concentrations. Finally, the presence of the mixed substrate changes dramatically the “washout” conditions for both substrates. All these facts point out that the biodegradation of chlorinated organics is more efficient in a mixed substrate environment.
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