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  • 1
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary For the efficient production of l-alanine from ammonium fumarate using the aspartase activity of immobilized Escherichia coli cells and l-aspartate β-decarboxylase activity of immobilized Pseudomonas dacunhae cells, alanine racemase and fumarase activities should be eliminated. We investigated various procedures to eliminate these side reactions, and found that both activities of intact E. coli cells could be eliminated by treating the culture broth at pH 5.0 and 45° C for 1 h, and those of intact P. dacunhae cells could be eliminated by treating the culture broth at pH 4.75 and 30° C for 1 h. Further, it was confirmed that l-alanine was efficiently produced using these two immobilized pH-treated microorganisms.
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  • 2
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The immobilized growing cell system using Serratia marcescens was applied to continuous L-arginine production. From the determination of oxygen uptake rate, it was shown that the cells entrapped in carrageenan gel were in an oxygen-limited state due to the diffusion barrier to oxygen transport created by the gel layer. This limited state in gel was relieved by supply of oxygen-enriched gas instead of air into the medium. The maximum population of immobilized cells increased to five times that of free cells with the supply of pure oxygen gas. The L-arginine-producing activity of the immobilized growing cells was proportional to the concentration of oxygen gas supplied and was 6 mg/h per millilitre in gel supplied with pure oxyges gas. The continuous L-arginine containing production was constantly maintained by controlling the medium penicillin G at pH 6.5 and more than 10 mg/ml of L-arginine were obtained at 10h of residence time for at least 12 days.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary In order to improve L-malic acid productivity by Brevibacterium flavum immobilized with ϰ-carrageenan, addition of Chinese gallotannin to the immobilization medium was investigated. As the results show, the optimal concentration of Chinese gallotannin was 0.1% (w/v). Fumarase activity and the stability of this improved preparation were higher than in one with only ϰ-carrageenan. Addition of Chinese gallotannin was more advantageous to stability towards ethanol than addition of polyethyleneimine. The L-malic acid productivity of the immobilized cells at 37°C was 42.2 kg/h per 1,000 l column, and increased threefold compared with that of B. flavum immobilized with only ϰ-carrageenan, and was 25 times that of B. ammoniagenes immobilized with polyacrylamide. Persimmon tannin also increased the stability of fumarase.
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  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary For continuous production of 6-aminopenicillanic acid (6-APA) the microbial cells ofEscherichia coli ATCC 9637 having high penicillin amidase (penicillin amidohydrolase, E.C. 3. 5. 1. 11) activity were immobilized by entrapment in a polyacrylamide gel lattice. Enzymatic properties of penicillin amidase of the immobilizedE. coli cells were investigated and compared with those of the intact cells. With regard to optimal pH and temperature, no marked difference was observed. The heat stability was somewhat increased by immobilization of the cells. The enzyme activity of the immobilized cell column was stable, and its half-life was 17 days at 40°C and 42 days at 30°C. From the effluent of the column, 6-APA was easily obtained in a good yield.
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  • 5
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Continuous production ofL-malic acid from fumaric acid using immobilized microbial cells was investigated. Several microorganisms having fumarase activity were immobilized into a polyacrylamide gel lattice. Among the microorganisms tested, immobilizedBrevibacterium ammoniagenes IAM 1645 showed the highest enzyme activity, but produced an unwanted by-product, succinic acid. Conditions for suppression of this side reaction were investigated, and bile extract treatment of immobilized cells was found to be effective. The bile extract treatment of immobilized cells also resulted in a marked increase of reaction rate forL-malic acid formation. No difference was observed between the native enzyme and immobilized cells in optimal pH and temperature of the enzyme reaction. The effect of temperature on the reaction rate and the stability of fumarase activity of an immobilized cell column were investigated under conditions of continuous enzyme reaction. The decay of enzyme activity during continuous enzyme reaction was expressed by an exponential relationship. Half-life of the fumarase activity of the immobilized cell column at 37°C was calculated to be 52.5 days.
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary To develop an efficient method for continuous production of L-malic acid from fumaric acid using immobilized microbial cells, screening of microorganisms having high fumarase activity was carried out and cultural conditions of selected microorganisms were investigated. As a result of screening microorganisms belonging to the genera Brevibacterium, Proteus, Pseudomonas, and Sarcina were found to produce fumarase in high levels. Among these microorganisms Brevibacterium ammoniagenes, B. flavum, Proteus vulgaris, and Pseudomonas fluorescens were further selected for their high fumarase levels in the cultivation on several media. These 4 microorganisms were entrapped into a k-carrageenan gel lattice, and the resultant immobilized B. flavum showed the highest fumarase activity and operational stability. Cultural conditions for the fumarase formation and the operational stability of fumarase activity of immobilized B. flavum are detailed. Productivity for L-malic acid using immobilized B. flavum with k-carrageenan was 2.3 fold of that using immobilized B. ammoniagenes with polyacrylamide.
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new immobilization of microbial cells based on the growth of cells in gel is presented. The cells grew very well in carrageenan gel when fed nutrients required for growth. The growing cells immobilized in gel formed a dense layer of cells near the gel surface. Because the cells were near the gel surface, they efficiently catalyzed single enzyme reactions. In addition, the immobilized growing cell system was applied to the complicated multienzyme reactions since large numbers of cells in the gel could constantly be maintained for long periods.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Escherichia coli cells possessing glutathione synthetase and acetate kinase activities were immobilized with carrageenan gel. To enhance the operational stability, immobilized cells were treated with hardening agent, glutaraldehyde in the presence of hexamethylenediamine. The continuous production of glutathione was investigated using the column packed with immobilized Escherichia coli cell preparations. Glutathione was continuously produced by this column in the presence of acetyl phosphate and the half-life of this column was calculated to be 8 days at the flow rate of S.V.=0.1 h−1 at 37°C.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Immobilized growing yeast cells were prepared in kappa-carra-geenan gel. Gel beads containing a small number of cells were incubated in a complete medium. The cells grew very well in the gel and the number of living cells per ml of gel increased to over 10 times that of free cells per ml of culture medium. After growing in the gel, the cells formed a dense layer of cells near the gel surface and produced large amounts of ethanol. The conditions for continuous production of ethanol using immobilized growing yeast cells were investigated. The supply of appropriate nutrients for growth was essential for the continuous production. The living cells in the gel were maintained at the high level of 109 per ml of gel and continuous production of ethanol using the complete medium containing 10% glucose was carried out with a retention time of 1 h. In this operation, a stable steady state was maintained for longer than 3 months. The ethanol concentration was 50 mg/ml and the conversion of glucose utilized to ethanol produced was almost 100% of the theoretical yield.
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  • 10
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Whole cells of Saccharomyces cerevisiae were immobilized in polyacrylamide gel. Consuming glucose, the immobilized cells produced glutathione from its constituent amino acids, and glutathione produced was excreted out of the gels. The conditions for immobilization of the yeast cells and for glutathione production were studied. Based on these data, the properties and the feasibility of the glycolytic pathway as an ATP regeneration system were discussed in reference to glutathione production.
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