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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 259-280 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Since it has not been possible to produce penicillin in tower-loop reactors with highly viscous filamentous molds of Penicillium chrysogenum which are employed in stirred-tank reactors, a new strategy has been developed to avoid the formation of this morphology and to use the pellet form of the fungi. When employing definite impeller speeds in the subculture in connection with definite inoculum amounts and substrate concentrations in the main culture (bubble column), it is possible to generate a suspension of isolated small pellets, which shows a low broth viscosity up to a sediment content of 45% over the entire fermentation time. Volumetric mass-transfer coefficients kLas are by a factor of 4 to 5 higher in these pellet suspensions than in filamentous broths. It was easy to maintain the necessary oxygen supply for penicillin production in these pellet suspensions. Under these conditions the specific penicillin productivities were higher with regard to power input (up to 90%), biomass, and consumed substrate than in the stirred-tank reactors with highly viscous filamentous morphology of the fungi. Under nonoptimized operating conditions the absolute penicillin production in the tower loop was 35% lower than in the stirred-tank reactor due to lower possible biomass concentrations. The separation of the biomass, and therefore the penicillin recovery, is much simpler when employing pellets. It is shown how the particular mass transfer resistances at the gas/liquid and liquid/pellet interfaces and within the pellets change with the pellet diameter. There should be a particular pellet diameter at which penicillin productivity has its maximum. These investigations indicate that the use of tower-loop reactors can, in the future, be an alternative for more economical penicillin production methods.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1024-1036 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A microcoaxial needle sensor with a tip diameter of ca. 0.7 μm was used as a microprobe to measure profiles of dissolved oxygen tension (DOT) within fixed pellets of Penicillium chrysogenum as a function of the DOT level around the pellet, in the presence and absence of bulk convective flow and turbulence. The investigations indicate that the oxygen transfer mechanism is complex. The results were interpreted by assuming the penetration convective flow into the entire pellet and penetration of turbulence into the outer range. A model was developed which was able to describe the measured DOT profiles very well. The model takes into account molecular and turbulent diffusion as well as convective flow as transfer mechanisms inside of the pellet. Structures of pellets used for microprobe measurements were evaluated by histological investigations. Considerable variations of mycelial density with radius within the pellets were found.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 33-43 
    ISSN: 0006-3592
    Keywords: knowledge-based system ; algorithmic systems ; time-dependent knowledge ; bioprocess automation ; bioprocess supervision ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the control of bioprocesses, a priori knowledge exists which cannot be readily incorporated as a mathematical model but which can be represented by language-based rules, such as “IF/THEN” conditions. This knowledge is usually implemented via a process operator for the automation of the fermentation. A knowledge-based system has been developed which can use this kind of knowledge and which is complemented by algorithmic systems, such as statistical analyses and mathematical modeling, for the supervision and control of a bioprocess. In this article, a description of this system is presented. Furthermore, the following features of the system are discussed in detail which are especially important for the development of real-time, on-line, knowledge-based systems: the representation of time-dependent knowledge; processing of imprecise, uncertain, and incomplete knowledge; the combination of shallow reasoning with model-based reasoning; informing the bioprocess operator about the inferences and decisions; the demands of the diversity of the knowledge handling; performance; and maintenance and extension of the system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0006-3592
    Keywords: E. coli JM103 ; fusion protein ; temperature induction ; chemical induction ; fed-batch ; airlift tower loop reactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SPA::EcoRI fusion protein was produced by Escherichia coli JM103 carrying the multicopy expression plasmid pMTC48, the multicopy repressor plasmid pRK248, and the multicopy protection plasmid pEcoR4 in a 60-L working volume airlift tower loop reactor on M9 minimal medium with glucose. Cell mass concentration, total cell count, number of colony-forming units, specific growth rate, yield coefficient, and metabolite (acetate, pyruvate, succinate, lactate, ethanol) concentrations were monitored during the growth phase and gene expression. Gene expression was induced by temperature shift or chemically by isopropyl-thiogalactosidase in the airlift tower loop reactor (ALTR) at constant cultivation time and in a small stirred tank reactor at different cultivation times. During induction, the cultivation medium was supplemented with concentrated Luria-Bertani (LB) medium. The intracellular enzyme activity was evaluated as a function of the time after the start of the induction. It was found that the reduction of the glucose concentration and increase of the dissolved oxygen concentration reduced the acetate produced and increased the intracellular enzyme activity. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 67 (1996), S. 276-280 
    ISSN: 0268-2575
    Keywords: simultaneous ; on-line monitoring ; glucose ; total sugar ; FIA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A flow injection analysis (FIA) system is presented which is able to monitor simultaneously and on-line the concentrations of glucose and total malto sugars during fermentation or hydrolysis processes. The system consists of glucoamylase (GA), glucose oxidase (GOD) EC 1.1.3.4 and mutarotase (MUT) EC 5.1.3.3 immobilized on synthetic polymer beads contained in cartridges serving as reactors. A high degree of selectivity towards non-malto sugars and carbohydrates, amino acids, and other possible components in the fermentation medium was exhibited by the system. The measurements delivered by the system during the monitoring of Bacillus licheniformis fermentation for protease production in complex media described the actual progress of the process. A correlation of the on-line measurements with the off-line enzymatic and off-line colorimetric measurements rendered correlation coefficients (r2) of 0·997 and 0·995, respectively. The enzyme reactors could be used on a long-term basis at 30°C and a pH of 5·5.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 14 (1993), S. 753-758 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Plasmid DNA prepared from cultivation samples of recombinant Escherichia coli was analyzed by capillary gel electrophoresis. We used this method to control the genetic stability during a fed-batch culture. The plasmid DNA and a standard DNA mixture with molecular weights in the size range of 3000-22 000 base pairs (bp) were analyzed in capillaries that were filled with solutions of non-cross-linked polyacrylamide. With this method the plasmid DNA from recombinant E. coli cultivation samples was analyzed within 30 min. Separation parameters such as gel concentration, capillary length and current were optimized for that purpose. The method was modified to allow the analysis of proteins. Crude cell lysate samples could be screened for the protein pattern within 15 min in sodium dodecyl sulfate-polyacrylamide filled capillaries. The method was also used to verify product purity after the down-stream process.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 61 (1994), S. 81-86 
    ISSN: 0268-2575
    Keywords: simultaneous determination ; starch ; glucose ; flow injection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A flow injection analysis (FIA) system capable of simultaneously determining the concentrations of starch and glucose in samples was set up. The system consisted of glucoamylase (GA), glucose oxidase (GOD), (EC 1.1.3.4) and mutarotase (MUT, EC 5.1.3.3) immobilized on macroporous polymer packed in reaction cartridges was operated at 30°C. Glucose resulting from the action of glycoamylase or originally present in the samples was determined amperometrically. The starch was analysed with the system without needing prehydrolysis with α-amylase, and inclusion of mutarotase was found necessary only when the sample originally contained α-glucose. A linear detection range up to 1.5 g dm-3 and 4.0 g dm-3 was obtained for the streams from which glucose and total sugar concentrations were measured, respectively. The system was able to analyse up to 10 samples per hour.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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