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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 419-425 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The implementation of adaptive control for a fed-batch culture in order to maximize the output of product based on a self-adjusting model is discussed in the present work. Optimization methods were applied to the generalized mathematical model of a fed-batch fermentation process to determine control algorithms that could be used for on-line process control. The efficiency of the proposed adaptive algorithms was investigated by simulating a model system. The model of amylotytic enzyme fermentation that was proposed by the authors was taken from a real process. Dynamic modelling has shown that the main problem of realization is connected with the on-line identification of the adaptive model's parameters. To avoid this problem, we have introduced special limitations on the parameters' time variations that increased the convergence of the identification algorithm. The results of the investigation have shown the efficiency of the proposed adaptive algorithms, and the results of this work should be investigated for real process control.
    Additional Material: 9 Ill.
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  • 2
    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.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 426-433 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alkali treatment and steam explosion of bagasse were investigated in order to develop economical and effective methods of increasing the digestibility of bagasse. The treated bagasse was to be used as a substrate for the production of volatile fatty acids by anaerobic acidogenic bacteria. The alkalis examined were NaOH, NH3 (aqueous), NaOH + NH3, Ca(OH)2, and Ca(OH)2 + Na2CO3, at ambient temperature and in combination with steam explosion at 200°C, 6.9 MPa, and 5 min cooking times. Digestibilities of up to 733 g organic matter (OM)/kg bagasse dry matter (DM) were obtained for bagasse treated with NaOH and Ca(OH)2 + Na2CO3; less than 430 g OM was obtained for bagasse treated with aqueous NH3; and up to 724 g OM was obtained for bagasse treated with Ca(OH)2. This digestibility was only achieved by using high concentrations of Ca(OH)2, i.e., 180-300 g/kg bagasse. Steam explosion increased the digestibility of bagasse up to 740 g OM in the presence of alkali but only to 610 g OM in the absence of alkali. The digestibility of bagasse without pretreatment was 190 g OM/kg bagasse DM. More than one-half the hemicellulose present was solubilized by pretreatment. The composition of the liquid fraction of steam-exploded material was examined and contained mainly xylose monomers and oligomers (112 g/kg original bagasse DM) and acetic acid (33 g/kg original DM). The relative costs of the alkalis used were obtained for the United States, Australia, and Europe. Lime [Ca(OH)2] was the least expensive alkali per unit of additional digestible OM obtained. Ammonia was the most expensive alkali to use, except in the United States where the difference in its cost relative to other alkalis was smaller. However, ammonia provides organic nitrogen for microbial growth, and could be recycled. With acidogenic fermentations, alkali is able to double as a neutralizing agent during fermentation. Thus, concentrations of alkali equal to that required for neutralization may be used in pretreatment. Concentrations of Ca(OH)2 as high as 300 g/kg bagasse were needed for neutralization and should, therefore, be considered for pretreatment. Steam explosion of bagasse resulted in digestible, sterilized substrates of small particle size with readily separable liquid and pulp streams.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 677-681 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chlorella sp. strain VJ79 was isolated from a total heterotrophic count of a wastewater collector. It grows autotrophically, heterotrophically, and mixotrophically on a variety of organic substrates. Glucose and serine promote a mixotrophic growth from which the yield is higher than the sum of autotrophic and heterotrophic yields, but serine assimilation requires light. The interaction of glucose and light was studied in proliferating and nonproliferating cells by respirometry (IRGA and Warburg) and growth experiments. Glucose inhibits the photosynthetic CO2 fixation ten-fold and modifies the pigmentary system as it does in heterotrophic cultures. Light inhibits glucose uptake and assimilation, but under mixotrophic conditions maximal utilization of glucose is obtained. Mutants defective in autotrophic growth were isolated by mutagenesis with nitrosoguanidine. They show a degenerated pigmentary system and a mixotrophic growth yield equal to that of the heterotrophic growth. The analysis of the mixotrophic system shows that light energy, dissipated during autotrophic growth, is used under mixotrophic conditions. From the increase in growth, the increase in photosynthetic efficiency can be calculated as ca. sixfold.
    Additional Material: 3 Ill.
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  • 5
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical description of a low-frequency, dual-source acoustic treatment of protein precipitates is presented. Two mechanisms for the potential improvement of the centrifugal separation of precipitates are proposed. They are acoustic aggregation, which causes an increase in particle size, and aggregate deformation, which results in an increase in aggregate density. Experiments with isoelectric soya protein precipitate indicated that the extent of ageing prior to acoustic conditioning is important. Support for both aggregation and dewatering was found and a maximum increases in the particle settling velocity of 20% was observed.
    Additional Material: 10 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 682-686 
    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 derives a number of equations which can be used in both continuous and the semicontinuous cultures of microorganism populations in chemostat systems. Using these equations, some phenomena which have been known for many years can be explained reasonably in terms of chemical kinetics, and a number of analytical solutions can be obtained instead of numerical solutions previously published.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 4 (1962), S. 23-36 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of a number of Ustilago species, especially Ustilago maydis (DC.) Cda., to produce lysine and threonine was investigated. The organisms were grown in shake flasks or in 10-l. fermentors. Lysine and threonine were found to be excreted into the medium both in the free and bound form. The bound amino acids could be released by acid hydrolysis or by enzymes from autolyzed cells. The optimal conditions for the release by autolysis were, in the case of Ustilago maydis (DC.) Cda., pH 4.3 and 45°C. An enzyme that could liberate lysine from the bound form(s) occurring in the broth was extracted from cells of Ustilago maydis (DC.) Cda. It exhibited an apparent pH optimum near 4.0. The effect of pH and temperature during the growth phase on the yield of lysine and threonine was studied in 10-l. fermentations.
    Additional Material: 5 Ill.
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  • 9
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of Ustilago maydis (DC.) Cda. to grow and to produce lysine and threonine was investigated in shake flask cultures. Growth and production of lysine and threonine increased markedly when aeration was increased. The optimal ratio of glucose to diammonium phosphate in the medium seemed to be approximately 10:1. Ammonium phosphate, ammonium sulfate, ammonium chloride, ammonium nitrate, sodium nitrate, urea, aspartic acid, glutamic acid, and glycine were readily used as nitrogen sources. Growth and amino acid production was poor on ammonium carbonate, ammonium acetate, ammonium citrate, trimethylamine, and betaine.U. maydis (DC.) Cda. was found to grow on a number of different carbohydrates. Besides D-glucose the organism could utilize D-mannose, D-galactose, D-fructose, L-arabinose, D-xylose, D-ribose, sucrose, maltose, and the polyalcoholes D-sorbitol, D-mannitol, and i-inositol. Pectin, dextrin, and corn starch treated with α-amylase could also be used but not untreated corn starch or lactose, cellobiose, D-sedoheptulose, glycerol, or D-glucosamine. The formation of lysine and threonine was better with disaccharides and hexoses than with pentoses.No specific effects on the formation of lysine and threonine could be observed from changes in the concentration of calcium, sodium, potassium, magnesium, zinc, iron, copper, manganese, cobalt, or molybdenum. The requirement of metal ions for growth is discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 4 (1962), S. 161-170 
    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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