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  • AERODYNAMICS  (851)
  • METEOROLOGY AND CLIMATOLOGY  (843)
  • Biochemistry and Biotechnology  (726)
  • ddc:330
  • 1980-1984  (2,420)
  • 1945-1949
  • 1925-1929
  • 1984  (1,389)
  • 1981  (1,031)
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  • 1980-1984  (2,420)
  • 1945-1949
  • 1925-1929
Year
  • 101
    Electronic Resource
    Electronic Resource
    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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    New York, NY [u.a.] : Wiley-Blackwell
    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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    New York, NY [u.a.] : Wiley-Blackwell
    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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    New York, NY [u.a.] : Wiley-Blackwell
    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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    New York, NY [u.a.] : Wiley-Blackwell
    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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    New York, NY [u.a.] : Wiley-Blackwell
    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
    Source: Wiley InterScience Backfile Collection 1832-2000
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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
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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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 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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  • 130
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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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  • 131
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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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  • 132
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    Biotechnology and Bioengineering 26 (1984), S. 121-127 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic model was devised for the hydrolysis and synthesis of maltose and isomaltose by two glucoamylases from Rhizopus niveus and Aspergillus niger, and the validity of the model was verified experimentally at 313 K and pH 5.0. For both enzymes, the formations of maltose and isomaltose from glucose were parallel reversible reactions, and glucosyl transfer between maltose and isomaltose was not observed. The enzymes catalyzed rapid hydrolysis and synthesis of maltose. Isomaltose was hydrolyzed and synthesized more slowly, but the level produced from glucose was much higher than that of maltose. These hydrolysis and condensation reactions were expressed well by the model.
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  • 133
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    Biotechnology and Bioengineering 26 (1984), S. 142-147 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass autoflocculation in outdoor algal cultures was found to be associated with increases of culture pH levels, due to CO2 consumption by the algal photosynthetic activity. Under these alkaline conditions, some medium chemical ions precipitated together with the algal biomass. The chemical substances involved with the process and its dependence on pH value were studied by simulation of autoflocculation in laboratory experiments. Proper concentrations of calcium and orthophosphate ions in the medium are important for autoflocculation and, in order to attain it within the pH range 8.5-9.0, the culture should contain 0.1mM-0.2mM orthophosphate and 1.5mM-2.5mM calcium prior to raising the pH level. Calcium phosphate precipitates are considered as the flocculating agent which reacts with the negatively charged surface of the algae and promotes aggregation and flocculation.
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    Biotechnology and Bioengineering 26 (1984), S. 188-190 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Biotechnology and Bioengineering 26 (1984), S. 194-196 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 136
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    Biotechnology and Bioengineering 26 (1984), S. 221-230 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymatic hydrolysis of cellulose for sugar production offers advantages of higher conversion, minimal by-product formation, low energy requirements, and mild operating conditions over other chemical conversions. The development of a kinetic model, based on observable, macroscopic properties of the overall system, is helpful in design and economic evaluation of processes for sugar conversion and ethanol production. A kinetic model is presented, incorporating enzyme adsorption, product inhibition, and considers a multiple enzyme and substrate system. This model was capable of simulating saccharification of a lignocellulosic material, rice straw, at high substrate (up to 333 g/L) and enzyme concentrations (up to 9.2 FPU/mL) that are common to proposed process designs.
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    Biotechnology and Bioengineering 26 (1984), S. 252-256 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dialysate-feed, immobilized-cell dialysis continuous fermentation system was investigated as a method of relieving product inhibition in the conversion of glucose to ethanol by cells of Saccharomyces cerevisiae ATCC 4126. The substrate was fed into a continuous dialysate circuit and then into a batch fermentor circuit via diffusion through the microporous membranes of an intermediate dialyzer. Simultaneously, product was withdrawn from the fermentor circuit through the dialyzer membranes into the dialysate circuit and out in the effluent. Since the fermentor was operated without an effluent, the cells essentially were immobilized and converted substrate to product by maintenance metabolism. Contrary to prior results with this novel system for the continuous fermentation of lactose to lactate by lactobacillus cells, a steady state of yeast cells in the fermentor did not occur initially but was obtained by the depletion of medium nitrogen and the prevention of cell breakage, although the substrate and product concentrations then became unsteady. The inherent advantages of the system was offset in the ethanol fermentation by relatively low productivity, which appeared to be limited by membrane permeability.
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    Biotechnology and Bioengineering 26 (1984), S. 275-284 
    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 that describes substrate utilization and cell growth in terms of two potentially rate-limiting enzyme systems has been developed. Consideration of substrate inhibition and enzyme repression have been incorporated. The model provides a rational approach for characterizing non-steady-state phenomena. The model has been used to analyze batch test data to illustrate the effects of inhibition, repression, and concurrent substrate utilization. Its utility lies in the fact that it provides a quantitative framework for describing changes in the activity levels of cells that result from changes in substrate concentration and/or substrate type. The lag phase resulting from exposure to a new substrate can be modeled.
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    Biotechnology and Bioengineering 26 (1984), S. 347-351 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Invertase immobilized onto corn grits was utilized in the hydrolysis of highly concentrated sucrose solutions producting liquid sugar solutions containing glucose and fructose. Comparisons of conversion efficiencies of this immobilized invertase in a continuous stirredtank reactor and a plug-flow reactor indicated that the plug-flow reactor has an higher efficiency. Continuous sucrose hydrolysis was then performed in 0.1- and 1-L tubular reactors. This tenforld scaling-up was achieved without any noticeable loss in efficiency. This process thus was scaled-up to a 17.6-L pilot reactor set in a cane sugar refinery. This reactor was fed with highly concentrated sucrose solutions [71% (w/w)] to produce invert sugar syrup with the desired inversion degree. It allows a productivity equal to 9.1 kg sucrose hydrolyzed/h in the case of a 69% (w/w) sucrose initial concentration with a 72% conversion rate.
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    Biotechnology and Bioengineering 26 (1984), S. 374-376 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 389-389 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 386-388 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 397-402 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 403-405 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 434-441 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fungi of the Aspergillus sp. can hydroxyate biphenyl to 4,4′-dihydroxybiphenyl, a chemical intermediate used in the plastics industry. The authors studied various batch culture conditions for the production of 4,4′-dihydroxybiphenyl, by Aspergillus toxicarius, in 25-mL shake flasks and 2-L fermenter cultures. Conditions investigated included temperature, aeration, carbon and nitrogen sources, biomass content, and time of substrate addition. Under optimum conditions we observed a rate of 4,4′-dihydroxybiphenyl production of 15-20 mg/day/g dry wt mycelia. Such a production rate is probably too low to support a commercial process and possible reasons for the low productivity are discussed.
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    Biotechnology and Bioengineering 26 (1984), S. 468-476 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic analysis of a continuous, aerobic, fixed-film bioreactor has been performed. Rigorous mathematical models have been developed for a fluidized-bed fermentor with biofilm growth. The transient performance of the reactor is appraised in terms of outlet penicillin concentration for constant, as well as variable carbon substrate feed rates. The effect of the reactor oxygen transfer capacity is elucidated for those cases employing substrate feeding strategies. The results show that penicillin production in a continuous, fixed-film bioreactor reaches a maximum with processing time, but subsequently decreases as cell mass accumulates and substrate deficiencies occur. The maximum production level can be maintained for increased operating times if the substrate supply is continuously increased. The duration of this prolonged production is a direct function of the rate of increase and the operating time at which the increase is initiated. The oxygen transfer capacity of the reactor was found to be important to the effectiveness of a feeding strategy.
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    Biotechnology and Bioengineering 26 (1984), S. 488-496 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some studies on the adsorption of cellulase on cellulose revealed part of the mechanisms involved in the enzymatic hydrolysis of cellulose and provided some clues to the synergistic mechanism of cellulase complex. The adsorption of cellulase was significantly affected by the reaction conditions and physical chemical characteristics of cellulose. Endoglucanase consisted of adsorbable and nonadsorbable components. Cellobiohydrolase had the strongest adsorption affinity. Each cellulase component is postulated to have distinctly different adsorption sites on cellulose, corresponding to the active sites in the hydrolysis reaction. Competitive adsorption kinetics between cellulase components were also observed during the adsorption process. The degree of competitive adsorption was most remarkable when the composition of cellulase components was nearly the same as that in the crude cellulase complex. This seems to show the optimal relative composition of cellulase components. The synergism between cellobiohydrolase and endoglucananse could be elucidated more clearly by this competitive adsorption model of the reaction mechanism.
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    Biotechnology and Bioengineering 26 (1984), S. 503-507 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two strains of human foreskin fibroblast cells were incapable of sustained growth in a matrix perfusion culture system, possibly because of their inability to attach to the fiber surfaces. Addition of microcarrier beads to the extracapillary space allowed attaining high cell densities in excess of 107 cells per culture unit. Microcarrier beads were tested in hollow fiber culture devices containing membranes of 104 or 105 D nominal porosities. Best results were obtained when initial cell densities of at least (2-3) × 106 cells were used in units with 105 D pore size membranes and DEAE-Sephadex or polyacryl-amide microcarrier beads in the extracapillary space. This extension of the matrix perfusion system should be useful for growing other anchorage dependent cells while retaining the advantages of perfusion culture.
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    Biotechnology and Bioengineering 26 (1984), S. 518-527 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Acid phosphatase (E.C.3.1.3.2.) thermal deactivation at pH 3.77 has been investigated by monitoring the enzyme activity as a function of time in the hydrolysis of p-nitrophenyl phosphate. The experimental curves obtained show a two-slope behavior in a log (activity)versus-time plot, which indicates that deactivation occurs via a complex mechanism. From the dependence of the kinetic parameters on both deactivation and hydrolysis temperatures, it is inferred that the deactivation mechanism involves intermediate, temperature-dependent, less-active forms of the enzyme. This interpretation is confirmed by the results of additional tests in which the temperature was suddenly changed during the deactivation process.
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    Biotechnology and Bioengineering 26 (1984), S. 528-536 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Plasmid gene product accumulation in a cell population depends on the fraction of plasmid-containing cells and the distribution of single-cell plasmid content. These important population properties have been related to plasmid replication regulation and kinetics and to plasmid segregation rules at the single-cell level using population balance mathematical models. Budding yeast populations are considered in detail because of the practical potential of yeast host-vector systems and because of the model complications introduced by the asymmetric division pattern observed for Saccharomyces cerevisiae at all but the largest growth rates. Solutions are presented for several different reasonable models of plasmid replication and segregation. The results offer potential for identification of important qualitative features of yeast plasmid replication and of model parameter values from average and segregated experimental data on yeast populations.
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    Biotechnology and Bioengineering 26 (1984), S. 557-559 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 560-563 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 573-582 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the oxygen limiting growth of Klebsiella oxytoca, the xylose metabolism may be considered as consisting of three components: conversion to 2,3-butanediol by “fermentation,” oxidation to carbon dioxide by respiration, and assimilation to cell mass. The amount of energy required for the assimilation of cell mass is assumed to determine the extent to which the two energy producing reactions occur. The activity of each energy producing pathway is also determined by the availability of oxygen and by the energy yield of each pathway. These relationships can be quantified by equating the ATP required for growth and maintenance to the ATP produced by the energy producing reactions. The resulting equation for butanediol production appears similar to the Luedeking and Piret model where the parameters α and β are related to the maximum cell yield from ATP and the maintenance energy requirement. These parameters were estimated from 14 batch fermentations, and the resulting simulation was used to describe the effects of the oxygen transfer rate and the initial xylose concentration on the yields and rates of the 2,3-butanediol fermentation.
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    Biotechnology and Bioengineering 26 (1984), S. 565-572 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Interaction of a number of arbitrarily chosen proteins with Triton X-100-substituted Sepharose 4B has been investigated. Of the proteins examined, bovine serum albumin, hemoglobin, glutamate dehydrogenase, and pepsin were found immobilized on the adsorbent. Binding of these proteins occurred irrespective of pH and NaCl concentration. Cytochrome c, used as a model protein, was totally immobilized only at low pH. Adsorption of glutamate dehydrogenase and pepsin took place with retention of their catalytic activities. Moreover, glutamate dehydrogenase used as a model allosteric enzyme, was found to retain its native properties upon binding to the adsorbent in the forms of suspension or column. Results are discussed in terms of specific interactions involving the hydrophobic region of Triton X-100 and the apolar patches or crevices present on the surface of protein molecules. Possible potential of the matrix as a method for preparation of biologically active immobilized proteins and its application in continuous operations are also discussed.
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    Biotechnology and Bioengineering 26 (1984), S. 604-612 
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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 dynamic mathematical model has been developed to describe microbial desulfurization of coal by Thiobacillus ferrooxidans. The model considers adsorption and desorption of cells on coal particles and microbial oxidation of pyritic sulfur on particle surfaces. The influence of certain parameters, such as microbial growth rate constants, adsorption-descrption constants, pulp density, coal particle size, initial cell and solid phase substrate concentration on the maximum rate of pyritic sulfur removal, have been elucidated. The maximum rate of pyritic sulfur removal was strongly dependent upon the number of attached cells per coal particle. At sufficiently high initial cell concentrations, the surfaces of coal particles are nearly saturated by the cells and the maximum leaching rate is limited either by total external surface area of coal particles or by the concentration of pyritic sulfur in the coal phase. The maximum volumetric rate of pyritic sulfur removal (mg S/h cm3 mixture) increases with the pulp density of coal and reaches a saturation level at high pulp densities (e.g. 45%). The maximum rate also increases with decreasing particle diameter in a hyperbolic form. Increases in adsorption coefficient or decreases in the desorption coefficient also result in considerable improvements in this rate. The model can be applied to other systems consisting of suspended solid substrate particles in liquid medium with microbial oxidation occurring on the particle surfaces (e.g., bacterial ore leaching). The results obtained from this model are in good agreement with published experimental data on microbial desulfurization of coal and bacterial ore leaching.
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    Biotechnology and Bioengineering 26 (1984), S. 627-627 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 642-645 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 647-653 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An ultrafiltration membrane reactor was used to investigate the recovery of biocatalysts during enzymatic hydrolysis of pretreated sallow. Product inhibition could be eliminated by continuous removal of products through the ultrafiltration membrane, thus retaining the macromolecular substrate and enzymes. In this way, the degree of conversion was improved from 40% in a batch hydrolysis to 95% (within 20 h), and the initial hydrolysis rate was increased up to seven times. The recovery studies were focused on mechanical deactivation and irreversible adsorption on to the nonconvertible fraction of the substrate. Cellulase deactivation during mechanical agitation was not significant, and the loss of activity was attributed mainly to strong adsorption of the enzymes onto undigested material. This process was studied in semicontinuous hydrolyses, where fresh substrate was added intermittently. The amount of reducing sugars produced in this experiment was 25.7 g/g enzyme, compared to 4.7 g/g enzyme in a batch hydrolysis.
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    Biotechnology and Bioengineering 26 (1984), S. 748-752 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida utilis was grown on a pineapple cannery effluent as the sole carbon and energy source in a chemostat at dilution rates between 0.10 and 0.62 h-1 to determine the growth kinetics. The principal sugars in the effluent were sucrose, glucose, and fructose. The cell yield coefficient on carbohydrate varied with dilution rate and a maximum value of 0.63 was observed at a dilution rate of 0.33 h-1. The steady-state concentrations of carbohydrate, reducing sugar, and chemical oxygen demand (COD) appeared to follow Monod saturation kinetics with increasing dilution rate, although none of the measured parameters represented a pure substrate. The maximum specific growth rate and reducing sugar saturation constant were 0.64 h-1 and 0.060 g/L, respectively. A maximum cell mass productivity of 2.3 g/L h was observed at a dilution rate of 0.51 h-1. At this dilution rate, only 68% of the COD was removed. A 95% COD removal was attained at a dilution rate of 0.10 h-1. Optimal yeast productivity and COD reduction occurred at a dilution rate of 0.33 h-1.
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    Biotechnology and Bioengineering 26 (1984), S. 775-780 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Solka Floc BW200 was enzymatically hydrolyzed in a batch reactor using a commercial cellulase preparation. A total of 50 different hydrolysis conditions were run within a 10-fold range in enzyme concentration and a 30-fold range in cellulose concentration. The data were evaluated in three ways using five different models. Previous literature models were not as successful in correlating the data as the HCH-1 Model derived in this work.
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  • 162
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    Biotechnology and Bioengineering 26 (1984), S. 800-802 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 163
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    Biotechnology and Bioengineering 26 (1984), S. 803-804 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 164
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    Biotechnology and Bioengineering 26 (1984), S. 814-819 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 165
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    Biotechnology and Bioengineering 26 (1984), S. 824-825 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 166
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    Biotechnology and Bioengineering 26 (1984), S. 844-847 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article presents several characteristics of a state-of-the-art fermentation air filter. The filter medium is composed solely of PTFE and has an absolute pore size rating of 0.2 μm. Quantitative bacteria and bacteriophage retention is shown based on live organism challenge tests. A nondestructive filter test, correlated to the microorganism challenge tests and called the Forward Flow Integrity Test, is described. This test has a sensitivity of one part in 1012 and can be performed in situ.
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  • 167
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    Biotechnology and Bioengineering 26 (1984), S. 857-859 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microscopic leaks in fermenter cooling coils were identified as the source of chronic fermentation contaminations. Methods used to identify the problem in production fermenters are described. Recommendations for upgrading quality control criteria for new installations are presented.
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  • 168
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    Biotechnology and Bioengineering 26 (1984), S. 877-884 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computer model is described which models an asynchronous population of E. coli by using a large, but finite number of representative single cells. Asynchrony generation and maintenance occurs at the single cell level by modulating the activity of an enzyme responsible for septum formation. Such modulation introduces cycle time imprecision and does not require the introduction of any new parameters into the single-cell model. Based on comparisons to experiment, reasonable predictions are possible for changes of cellular dry weight during exponential growth and turbidostat washout, and overall chemostat cell yields and changes in cell number, glucose concentration, and cell size distribution for a chemostat subject to a step change in dilution rate. Additionally, a correlation between cell RNA content and size is predicted as is an inertial effect when chemostat residence time is decreased under conditions of initially high glucose concentrations. Limitations imposed by the model's finite nature and their solutions are discussed.
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  • 169
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    Biotechnology and Bioengineering 26 (1984), S. 901-904 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilized β-galactosidase was obtained by crosslinking the enzyme with hen egg white using 2% glutaraldehyde. The gel obtained could be lyophilized to give a dry enzyme powder. The pH optimum of both the soluble and immobilized enzyme was found to be 6.8. The immobilized enzyme showed a higher Km for the substrates. The extent of enzyme inhibition by galactose was reduced upon immobilization. The stability towards inactivation by heat, urea, gamma irradiation, and protease treatment were enhanced. The bound enzyme as tested in a batch reactor could be used repeatedly for the hydrolysis of milk lactose. The possible application of this system for small-scale domestic use has been suggested.
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  • 170
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    Biotechnology and Bioengineering 26 (1984), S. 551-553 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 171
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    Biotechnology and Bioengineering 26 (1984), S. 1167-1175 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rheological behavior of cultures of Cellulomonas uda with shredded printed newspaper as the carbon source was studied. The initial substrate concentrations ranged from 23 to 60 g/L. The changes in apparent viscosity were followed on-line by applying a commercially available process viscometer and discretely using a rotational viscometer with an anchor impeller. During the time of highest cellulose degradation, the broths exhibited a pseudoplastic behavior which could be explained satisfactorily by the power-law model. At the end of cultivation when cellulose degradation slowed down, the broths became Newtonian in behavior. Endo-1,4-β-glucanase, 1,4-β-xylanase, β-glucosidase, and β-xylosidase activities were also determined during cultivation as well as cellulose degradation and cell mass production. The beginning of endoglucanase formation and the start of the final viscosity decrease of the bacterial paper pulp suspensions could be correlated.
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  • 172
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    Biotechnology and Bioengineering 26 (1984), S. 1146-1154 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: α-Chymotrypsin was immobilized with a high coupling yield (up to 80%) to tresyl chloride activated Sepharose CL-4B.The immobilized enzyme was tested for its ability to synthesize soluble peptides from N-acetylated amino acid esters as acyl donors and amino acid amides as acceptor amines in water-water-miscible organic solvent mixtures. It was found that the yield of peptide increased with increasing concentration of organic cosolvent. Almost complete synthesis (97%) of Ac-Phe-Ala-NH2 was obtained from Ac-Phe-OMe using a sixfold excess of Ala-NH2. The rate of peptide formation in aqueous-organic solvent mixtures was good. Thus, 0.1M peptide was formed in less than 2 h in 50 vol% DMF with 0.1 mg immobilized chymotrypsin/mL reaction mixture. The immobilized enzyme distinguished between the L and D configurations of acceptor amino acid amides even in high concentration of nonaqueous component (90% 1,4-butanediol). The effect of temperature was studied. It was found that both the yield of peptide and the stability of immobilized enzyme increased when the temperature was lowered. Experiments could be performed at subzero temperatures in the aqueous-organic solvent mixtures resulting in very high yield of peptide. After three weeks continuous operation at 4°C in 50% DMF, the immobilized enzyme retained 66%of its original synthetic activity. The activity of the immobilized enzyme was better conserved with a preparation made from agarose with a higher tresyl group content compared to a preparation made from a lower activated agarose, indicating that multiple point of attachment has a favorable effect on the stability of the enzyme in aqueous-organic solvent mixtures. The major advantage of using water-miscible instead of water-immiscible organic solvents to promote peptide syntheses appears to be the increased solubility of substrates and products, making continuous operation possible.
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    Biotechnology and Bioengineering 26 (1984), S. 1209-1218 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Relationships between the total rate of biomass growth and the rate of ammonia addition to a fermentor for pH control are presented. These equations make use of the concept of reaction invariants and provide the additional information needed for bioreactor identification. They are especially useful when the RQ measurement is not sufficient for this purpose, such as when sensitivities arise with the measured values of the respiratory quotient or when fermentation products are formed. The cases of batch, fed-batch and continuous fermentations, forming products with or without acidic/basic properties are considered. The derived relationships were successfully tested with nonbiological acid-base continuous flow reaction systems and subsequently applied to the identification of the continuous yeast fermentation of glucose to ethanol. Results of these experimental studies are also presented.
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  • 174
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    Biotechnology and Bioengineering 26 (1984), S. 1227-1232 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dihydrofolate reductase, purified to homogeneity from amethopterin-resistant Lactobacillus casei, was immobilized by coupling to cyanogen bromide-activated Sepharose or carbodiimide-activated CH-Sepharose. Coupling yields were determined by amino acid analysis following the hydrolysis of the gel. Enzyme activity was measured by the conventional spectrophotometric procedure, thus permitting the facile characterization of the immobilized enzyme. The pH optimum of the immobilized enzyme was shifted to 5.8 compared with pH 5.5 for the soluble enzyme. The immobilized enzyme retained greater than 90%of the initial activity over a six-month period and could be reused as many as ten times without loss of activity. As observed with the soluble enzyme, the activity of immobilized enzyme, which was lost on denaturation with 4M guanidine hydrochloride, was recovered rapidly and completely by washing the gel with buffer. The Kmapp values for dihydrofolate and NADPH for the immobilized enzyme were increased 15-164-fold over the Km values measured for soluble dihydrofolate reductase. Scatchard analysis of the interaction of amethopterin with the immobilized enzyme yielded linear plots and a Kdapp value of 0.56 ×10-8M, and revealed that all of the immobilized enzyme molecules were capable of binding the ligand.
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    Biotechnology and Bioengineering 26 (1984), S. 1258-1260 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 26 (1984), S. 1272-1281 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The internal regulatory processes, which underlie a variety of behavior in microbial growth on multiple substrates, are viewed as a manifestation of an invariant strategy to optimize some goal of the cells. A goal-seeking or cybernetic model is proposed here, with the optimization obased on a short-term perspective of response to the environment. The model parameters are determined from the growth data on single substrates. The model predicts the entire range of microbial growth behavior on multiple substrates from simultaneous utilization of all sugars to sequential utilization with pronounced diauxic lags. It is shown to predict the many variations of the diauxic phenomenon in different growth conditions. The transients in continuous culture growth on mixed substrates caused by varying the feed strategies are easily simulated by this model. The framework of this model can be applied to batch or continuous culture growth of many bacteria on different combinations of substrates.
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    Biotechnology and Bioengineering 26 (1984), S. 1294-1305 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oil residues arising from the Christos-Bitas spillage were found to contain 28% of oil extractable by carbon tetrachloride; the remainder comprised water and undefined solids. When incubated in 8-L rectangular tanks with a mixed population of mainly bacteria to which diammonium hydrogen phosphate was added, ca. 97% of the Christos-Bitas oil fraction was degraded. When the same substrate was degraded by only three isolated Pseudomonas strains in 1-L cylindrical tanks, degradation was only ca. 56%. Raising the temperature from 20 to 50°C brought about a visible loss in cell viability with only ca. 38% of the substrate degraded. Oil degradation proceeded in direct proportion to increases in cell attachment to the dispersed oil. The aliphatic fraction of Kuwait crude oil up to nC25 measured by gas liquid chromatography (GLC) was oxidized within 48 h. Using this substrate the three pseudomonads together brought about a more complete degradation (87%) than a single Bacillus isolate. The Bacillusstrain was capable of deggrading between 50 and 65% of the crude, depending on whether diammonium hydrogen phosphate supplemented a peptone-based medium. The preferential biodgradability of fractions was the following aliphatics 〉 aromatics 〉 asphalts, as has been widely reported.
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    Biotechnology and Bioengineering 26 (1984), S. 1330-1333 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mercury-resistant bacteria, which are able to reduce mercuric ion (Hg2+) to metallic mercury (Hg0), were examined for their ability to remove mercury from waste-water aerobically. Growth studies in artificial medium indicated that mercury increases the lag phase, but does not effect the growth rate of these bacteria. Further studies demonstrated that growth was minimal during a phase of rapid mercury removal, after which growth resumed. Small but significant amounts of carbohydrates are required for the mercuric ion reduction. Prolonged periods of bacterial growth under nonsterile conditions was accomplished without the loss of the mercuric reducing ability of the culture. A continuous culture of the resistant organism was maintained on raw sewage for two weeks, during which time relatively high concentrations of mercury (70 mg/L) were removed from the sewage at a rate of 2.5 mg/L h and at efficiencies exceeding 98%.
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  • 179
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    Notes: Proper design of fermentation facilities and equipment modification can control the risks associated with largescale production and purification of microbially produced cytotoxic agents and oncogenic viruses. The primary biohazard risks to operators and the environment are generation of aerosols and accidental spills. Fermentation and recovery facilities can be constructed to contain these agents by installing fermentation equipment within a HEPA-filter-exhausted biological barrier. Within this barrier system, large-scale processing that generates potentially hazaradous areosols (filtration, centrifugation of transformed cells or crystal slurries, and banding of viruses) should be isolated from other operations. Isolation of equipment is often required, with provision for both chemical and biological decontamination of process wastes. Failsafe fermentor over-pressure sensors, parallel exhaust gas filtration, welded transfer lines, and modified sampling systems for elimination of aerosols can be installed on most fermentation equipment. Aerosol and spill containment by proper equipment design, coupled with appropriate personnel protective equipment and medical monitoring, make possible safe production of experimental growth factors and viruses from large-scale culture of transformed mammalian cells and production of cytotoxic antitumor antibiotics.
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    Biotechnology and Bioengineering 26 (1984), S. 892-900 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proteins have been immobilized in porous support particles held in a fixed-bed reactor through which protein solution is continuously circulated. Changing the recirculation flow rate alters the observed immobilization kinetics and the maximum enzyme loading which can be achieved for glucose oxidase and glucoamylase on carbodiimide-treated activated carbon and for glucoamylase immobilized on CNBr-Sepharose 4B. Direct microscopic examination of FITC-labelled protein in sectioned Sepharose particles and indirect activity-loading studies with activated carbon-enzyme conjugates all indicate that immobilized enzyme is increasingly localized near the outer surface of the support particles at larger recirculation flow rates. Restricted diffusion of enzymes may be implicated in this phenomenon. These contacting effects may be significant considerations in the scaleup of processes for protein impregnation in porous supports, since apparent activity and stability of the final preparation depend on internal protein distribution.
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    Biotechnology and Bioengineering 26 (1984), S. 911-915 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzymatic method for the preparative resolution of racemic carnitine (whose L-isomer and its acyl-derivatives have numerous therapeutical applications) has been developed. It is based on our finding that electriceel acetylcholinesterase hydrolyzes the D- but not the L-isomer of acetylcarnitine. (Another cholinesterase tested, horse serum butyrylcholinesterase, is also stereospecific and hydrolyzes only the L-isomer of butyrylcarnitine.) Acetylcholinesterase, covalently attached to alumina, was employed for the resolution of D,L-carnitine; the latter was first chemically acetylated, then stereoselectively hydrolyzed with the immobilized enzyme, and finally the acetyl-L-carnitine and D-carnitine produced were separated by ion-exchange chromatography. Gram quantities of D,L-carnitine were thereby resolved.
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    Biotechnology and Bioengineering 26 (1984), S. 1455-1464 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The yield from glucose of ammonia-grown carbon-limited continuous cultures of Penicillium stipitatum was ca. 20% higher than that of nitrate-grown cultures at all growth rates examined. However, the yield from oxygen was similar during growth on both nitrogen sources. Under phosphate limitation the specific rate of gluconic acid and stipitatic acid production increased with growth rate, but the former product accounted for virtually 100% of the excreted carbon. Stipitatic acid was not produced under nitrogen limitation, and glucose supplied to the culture in excess of that required for growth was virtually quantatively converted into gluconic acid. Productivities of 11.4 g gluconic acid/L/h were stably maintained in continuous culture. Under conditions of glucose excess the enzyme glucose oxidase was excreted into the culture. The specific activity of this extracellular enzyme increased when the input glucose concentration to the culture was progressively increased. The excretion of a protein under nitrogen limitation suggests that this enzyme plays an important role under these conditions. Indeed, it was demonstrated that nitrogen-limited cultures did not overmetabolize gluconate at either pH 6.5 or 3.5, although up to 29 g/L gluconate was present in the culture. The Ygluconate and YO2 of C- and N-limited gluconate-grown cultures were similar indicating that the rapid conversion of glucose to gluconate probably affords a means of regulating carbon flow in this organism. Nitrogen-limited cultures of P. stipitatum overmetabolized glucose to a much greater extent than acetate, fructose, or gluconate.
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    Notes: Growing cells of Saccharomyces cerevisiae immobilized in calcium alginate gel beads were employed in fluidizedbed reactors for continuous ethanol fermentation from cane molasses and other sugar sources. Some improvements were made in order to avoid microbial contamination and keep cell viability for stable long run operations. Notably, entrapment of sterol and unsaturated fatty acid into immobilized gel beads enhanced ethanol productivity more than 50 g ethanol/L gel h and prolonged life stability for more than one-half year. Cell concentration in the carrier was estimated over 250 g dry cell/L gel. A pilot plant with a total column volume of 4 kL was constructed and has been operated since 1982. As a result, it was confirmed that 8-10%(v/v)ethanol-containing broth was continuously produced from nonsterilized diluted cane molasses for over one-half year. The productivity of ethanol was calculated as 0.6 kL ethanol/kL reactor volume day with a 95% conversion yield versus the maximum theoretical yield for the case of 8.5% (v/v) ethanol broth.
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    Biotechnology and Bioengineering 26 (1984), S. 1032-1037 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process of enzyme immobilization under the diffusion-controlled regime (i.e., fast attachment of enzyme compared to its diffusion) is modeled and theoretically solved in this article. Simple and compact solutions for the penetration depth of immobilized enzyme and the bulk enzyme concentration versus time are presented. Furthermore, the conditions for the validity of our solutions are also given in this article so that researchers can discover when the theoretical solutions can be applied to their systems.
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    Biotechnology and Bioengineering 26 (1984), S. 1026-1031 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: After transforming host cells of Bacillus stearothermophilus CU21 with a recombinant plasmid pLP11 that harbored constitutive penicillinase genes of B. licheniformis CO1, both the stability of the plasmid and specific rate of penicillinase production were studied. The temperature at which the plasmid could be kept in a stable fashion in the transformant of B. stearothermophilus CU21 (pLP11) ranged nearly from 44 to 50°C, irrespective of batch and continuous cultures. Continuous and steady-state cultures of the transformant could only be realized within this narrower temperature range. Indeed, the approximate temperature ranges of growth for the host and transformant were from 40 to 70°C and from 40 to 63°C, respectively. Clearly, the upper limit for the growth temperature of host cells decreased when they were transformed. Kinetic patterns of penicillinase production in continuous culture of the transformant (with plasmid) from 44 to 50°C differed remarkably from that of B. licheniformis CO1 (without plasmid) at 37°C.
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    Biotechnology and Bioengineering 26 (1984), S. 1066-1070 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effectiveness of attaching flavin adenine dinucleotide (FAD) via a C bridge to Teflon-bonded carbon black (CB), and the subsequent immobilization of glucose oxidase on the FAD-modified electrodes has been studied by cyclic voltammetry. When FAD alone is bound to the electrode, it undergoes reduction and oxidation at -0.62 and -0.5 V, respectively - values similar to those obtained with free FAD. Compared to the free enzyme, the reduction of FAD as part of the immobilized enzyme is 200 mV more cathodic, while the oxidation potential remains the same in both cases.
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    Biotechnology and Bioengineering 26 (1984), S. 1079-1084 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In search of hypercellulolytic microorganisms, ultraviolet irradiation carried out with Penicillium funiculosum has yielded a superior mutant. The investigations reported in this article are shake flask studies on some important nutritional requirements of the mutant, namely, nitrogen source, carbon source, and inducers. The mutant shows an ability to metabolize inorganic nitrogen sources like urea and sodium nitrate both for growth and enzyme production. A comparison of the long-term saccharification ability and the utilization efficiency of the mutant enzyme with those reported in the literature is also carried out, showing the superior performance of the mutant enzyme.
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    Biotechnology and Bioengineering 26 (1984), S. 1131-1133 
    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 26 (1984), S. 1136-1138 
    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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  • 190
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    Biotechnology and Bioengineering 26 (1984), S. 1140-1140 
    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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  • 191
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    Biotechnology and Bioengineering 26 (1984) 
    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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  • 192
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    Biotechnology and Bioengineering 26 (1984), S. 1189-1197 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The on-line bioreactor identification methodology of the preceding article (Part I) was tested with a series of numerical simulations and laboratory experiments. Results of these studies presented herein confirm the superior characteristics of the proposed estimator and its applicability to modelling studies, or on-line bioreactor control. The sensitivity of the estimation scheme with respect to the respiratory quotient measurement is discussed, and suggestions to bypass these problems are offered.
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  • 193
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    Biotechnology and Bioengineering 26 (1984), S. 1223-1226 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: After periodate oxidation of its glycosidic component, invertase was covalently bound onto three types of modified solid supports: glycidyl methacrylate, styrene-divinylbenzene copolymers, and bead cellulose. Direct reaction of the invertase aldehyde groups that were formed with amino groups of the support and use of the modified Ugi reaction have been employed as immobilization procedures. Apart from binding methods, the important effects of the buffer, support, conditions of periodate oxidation, and the length of the spacer on the activity of the enzyme conjugate have been investigated. Superior conjugate activity was obtained, via modified Ugi reaction, by the immobilization of a suitably oxidized invertase to a styrene-divinylbenzene copolymer having free amino groups.
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  • 194
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    Biotechnology and Bioengineering 26 (1984), S. 1245-1251 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The forces required to remove living, fully attached barnacles from the surface of a number of polymeric solids were measured. The forces were related to the surface energy components of the materials. The results indicate a positive correlation between polymer surface energy and force required for barnacle removal. The nonpolar component of the surface energy was more closely related to the removal force than the polar component, although the polar component is significant. Adherence to some composite materials was greater than was consistent with the correlation for noncomposites.
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  • 195
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    Biotechnology and Bioengineering 26 (1984), S. 1372-1382 
    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 based on known molecular interactions has been formulated to describe quantitatively regulation of expression of the lactose (lac) operon in the Escherichia coli chromosome and in multicopy plasmids. This model is genetically structured such that a nucleotide sequence change affecting transcription initiation at the lac promoter-operator influences one or very few directly corresponding model parameters. The model simulates chromosomal lac operon function in good agreement with previous experimental measurements for many lacl and lacO mutant systems as well as for diploid cells which carry F'lac episomes. Simulation results clearly show the loss of cloned lac operator regulation as the plasmid copy number increases, in agreement with experimental trends. The importance of this class of models in designing DNAs, organisms, and reactors for precise regulation of cloned gene expression is discussed.
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  • 196
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    Biotechnology and Bioengineering 26 (1984), S. 1398-1401 
    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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  • 197
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    Biotechnology and Bioengineering 26 (1984), S. 1436-1444 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In many anaerobic fermentation processes, high energy bonds in adenosine triphosphate (ATP) are produced when available electrons are converted from organic substrate into extracellular organic products such as ethanol. The true growth yield and maintenance parameters are directly related to the product formation kinetic parameters for these anaerobic processes. Methods are presented which allow all of the experimental measurements to be used simultaneously to estimate these parameters. Results are presented for several different anaerobic fermentations.
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  • 198
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    Biotechnology and Bioengineering 23 (1981), S. 19-27 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pilot-scale investigations into the application of ultrafiltration (UF) for concentrating bovine blood or a mixture of bovine and ovine blood are described. Tests were carried out in an Iopor 6CL UF system and a Romicon (hollow fiber) UF system. Optimal operating conditions for these two system were evaluated. Starting from a 18-20% TS lood concentration final concentrations of 28-30% TS were achieved. The lopor system was found to be more suited for processing blood and the average flux values obtained indicated UF to be a more economical process for concentrating blood than vacuum evaporation.
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  • 199
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    Biotechnology and Bioengineering 23 (1981), S. 79-95 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A flat-bed hollow-fiber cell culture system has been developed which maximizes the utilization of the large fiber surface while diminishing significantly the problems inherent in a cartridge-type reactor. The reactor core consists of a shallow bed of hollow fibers sandwiched between two stainless-steel microporous filter plates through which the media flow is directed normal to the plane of the fiber bed. Reactors with both 930 and 9300 cm2 of fiber surface have been successfully constructed and operated. A variety of cells has been grown in these reactors including SV3T3 cells, baby hamster kidney cells, Vero cells, and rhesus money kidney cells, and cell products such as plasminogen activator and migration inhibition factor (MIF) were produced. This system offers an excellent prototype for scaleup design.
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  • 200
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    Biotechnology and Bioengineering 23 (1981), S. 185-199 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mixed cultures which were used were isolated from municipal sludge digesters, and the production of organic acids (acetic, propionic, butyric, etc.) from carbohydrates was tested. The behavior of the reference population (culture R) obtained directly from the sewage treatment plant, is compared to that obtained after three months in a plug-flow reactor (Gradostat fermentor) without pH control (culture A) and after six months with pH control (culture B). For culture B, the specific rate of acid production is related to the cell growth rate by (1/X)rp= 17 µ + 1.6 with a maximal acid concentration of 40 g/liter. The batch culture yields are improved from 0.36g/g for the initial culture (R) to 0.72 g/g for culture B after six months in continuous culture, and 0.8 g/g in plug-flow continuous culture. The productivity of organic acids reaches 1.7 g/liter·hr. It is suggested that the acidogenic fermentation, the first step of methanogenesis, is a potential process to produce acetic, propionic, and butyric acids.
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