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  • Articles  (140)
  • fermentation  (140)
  • Process Engineering, Biotechnology, Nutrition Technology  (140)
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Bioresource Technology 50 (1994), S. 17-23 
    ISSN: 0960-8524
    Keywords: Lignocellulosic biomass ; Trichoderma reesei ; enzymatic hydrolysis ; ethanol production ; fermentation
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 2
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    Amsterdam : Elsevier
    Bioresource Technology 47 (1994), S. 97-101 
    ISSN: 0960-8524
    Keywords: Sugar-beet pulp ; Trichoderma reesei ; fermentation ; mouse feeding
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 3
    Electronic Resource
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    Amsterdam : Elsevier
    Bioresource Technology 49 (1994), S. 237-241 
    ISSN: 0960-8524
    Keywords: Fish silage ; feed valorization ; fermentation ; yeast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 4
    Electronic Resource
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    Amsterdam : Elsevier
    Bioresource Technology 47 (1994), S. 87-88 
    ISSN: 0960-8524
    Keywords: Pig faeces wastelage ; effect of molasses ; fermentation ; lactic acid bacteria
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 5
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    Amsterdam : Elsevier
    Bioresource Technology 47 (1994), S. 195-203 
    ISSN: 0960-8524
    Keywords: BOD ; COD ; Whey ; ethanol ; fermentation ; methane ; yeast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 6
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    Amsterdam : Elsevier
    Bioresource Technology 48 (1994), S. 169-172 
    ISSN: 0960-8524
    Keywords: Cellulose ; citrus waste ; fermentation ; hemicellulose ; pectins ; polysaccharide ; xanthan
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 7
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    Amsterdam : Elsevier
    Enzyme and Microbial Technology 7 (1985), S. 217-219 
    ISSN: 0141-0229
    Keywords: Ethanol ; adsorption ; fermentation ; inhibition ; silicalite ; xylose
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 8
    ISSN: 0141-0229
    Keywords: Biotransformation ; biocatalysis ; fermentation ; leukotriene receptor antagonist ; lipase
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 9
    ISSN: 0141-0229
    Keywords: Recombinant DNA ; fermentation ; heterologous expression ; polyelectrolyte ; polyethyleneimine ; precipitation ; protein fusion ; secretion ; yeast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 10
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    Amsterdam : Elsevier
    Enzyme and Microbial Technology 15 (1993), S. 899-900 
    ISSN: 0141-0229
    Keywords: Bioprocessing ; digestible energy ; fermentation ; harvest index ; hydrolysis ; hydroponic crops ; space
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 11
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    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 66-71 
    ISSN: 0141-0229
    Keywords: Esters ; beer ; fermentation ; industrial ; kinetics ; stirred-tank
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 12
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    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 922-932 
    ISSN: 0141-0229
    Keywords: Xylose ; fermentation ; genetics ; strain selection ; taxonomy ; yeast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 13
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    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 944-956 
    ISSN: 0141-0229
    Keywords: Candida shehatae ; Hemicellulose hydrolyzate ; Pichia stipitis ; d-xylose ; ethanol ; fermentation ; kinetic parameters ; lignocellulose ; pentose sugars ; xylitol ; yeast
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 14
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    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 719-722 
    ISSN: 0141-0229
    Keywords: Zeolite ; ethanol ; fermentation ; molasses ; sugarcane
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 15
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    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 281-283 
    ISSN: 1573-0972
    Keywords: Adaptation ; fermentation ; hemicellulose ; hydrolysate ; overliming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The fermentability of a corn cob, acid-hydrolysed hemicellulose by Pichia stipitis was considerably improved by pre-treatment with Ca(OH)2. The total sugars utilized and ethanol yield for the untreated hydrolysate were 18% and 0.21 g/g, respectively, compared with 82% and 0.32 g/g respectively for the treated material. Adaptation of the yeast to the hydrolysate resulted in a significantly higher fermentation rate with over 90% of the initial total sugars being utilized and an ethanol yield and maximum ethanol concentration of 0.41 g/g and 13.3 g/l, respectively.
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  • 16
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    World journal of microbiology and biotechnology 14 (1997), S. 101-106 
    ISSN: 1573-0972
    Keywords: Batter bread ; fermentation ; Lactobacillus ; maize ; sensory evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Eight lactic acid bacteria were isolated from fermenting maize meal. They were identified as Lactobacillus brevis, L. casei, L. fermentum, Pediococcus acidilacti, P. pentosaceus, Lactobacillus spp. I and Pediococcus spp. I and II. L. brevis and Lactobacillus spp. I isolated from the spontaneously fermented maize meal together with L. brevis isolated from rye sour dough and L. plantarum from ogi, a fermented maize gruel, were selected as starter organisms. There was a decrease in the final pH from 4.9 to 3.8 and an increase in the acid equivalent and temperature of the spontaneously-generated sour maize meal at the end of 24h fermentation. There was a decrease in the pH and moisture content of the sour maize breads relative to the conventional wheat bread. An improvement in the shelf-life of the bread samples was also obtained. Crude protein values of the sour maize breads were between 4.36% and 8.87%, while crude fat contents ranged between 3.66% to 7.67%. The ash contents increased from 2.29% to 2.54% while total carbohydrate values were between 46.31% and 65.3%. Calcium, phosphorus and potassium contents ranged from 0.015, 0.26 and 0.018% to 0.036, 0.47 and 0.036% respectively. Physical examination of the bread samples showed that all were cracked and relatively hard. Weight, height and volume ranged from 316 to 380g; 4.2 to 5.2cm and 200 to 320cm3 respectively. Statistical analysis of the sensory attributes revealed a consumer acceptance of the sour maize breads, although ranking test showed preference for the baker's yeast leavened bread that served as a control.
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  • 17
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    World journal of microbiology and biotechnology 9 (1993), S. 381-382 
    ISSN: 1573-0972
    Keywords: Cocoa beans ; fermentation ; products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The maximum amounts of acetic acid produced by ripe and unripe cocoa beans were 157 mg and 110 mg/10 g wet wt of cotyledon, respectively. The unripe beans had a lower pH than the ripe beans after 6 days' fermentation. About 40% of ripe beans achieved a chocolate colour compared with 27% of unripe beans.
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  • 18
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    World journal of microbiology and biotechnology 10 (1994), S. 410-413 
    ISSN: 1573-0972
    Keywords: Enterobacteriaceae ; fermentation ; lactic acid bacteria ; maize ; mawè ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lactic acid bacteria increased from 3.2 × 106 and 1.6 × 107 c.f.u./g (wet wt) to 2 × 109 and 1.6 × 109 c.f.u./g after 12 to 24 h of fermentation of home-produced mawè (a dough produced from dehulled maize) and commercial mawè, respectively. In commercial mawè, the yeast count increased from 1.3 × 105 to 2.5 × 107 c.f.u./g after 48 h of fermentation before decreasing, whereas in the home-produced mawè it increased from 2.5 × 104 to 3.2 × 107 c.f.u./g after 72 h of fermentation; the dominant yeasts were mainly Candida krusei, although C. kefyr, C. glabrata and Saccharomyces cerevisiae were also present. Enterobacteriaceae counts increased slightly during the initial stage ofthe fermentation, but decreased below the detection level after 24 to 48 h. Enterobacter cloacae was mostly found in commercial mawè and Escherichia coli mostly in homeproduced mawè.
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  • 19
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    World journal of microbiology and biotechnology 15 (1999), S. 231-234 
    ISSN: 1573-0972
    Keywords: starter-cultures ; garri ; cassava ; fermentation ; carriers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Garri is a popular food in Nigeria derived from the fermentation of the mash obtained from the enlarged root of the cassava plant, Manihot esculenta Crantz. As currently produced, the mash used for garri production is spontaneously fermented; on account of this, there is great variability in the organoleptic properties and the quantities of residual cyanide in the garri from Nigeria. The use of starter cultures can help ensure uniformity in these properties if dry carriers can be found on which the fermentative organisms can survive for extended periods so as to facilitate the transportation of their carriers to the many small and scattered garri producers. We therefore studied the survival, singly or mixed, on dry starchy substrates derived from locally available crops, of Lactobacillus coryneformis, Lact. delbruckii, and Saccharomyces sp., which are associated with garri production, as carriers for these organisms. After 16 weeks of storage, between 75% and 85% of the organisms survived on yam, coco-yam, cassava in that order, whereas between 40 and 65% survived on rice and garri. Refrigeration at 4 °C did not improve the survival of the organisms, when compared to room temperature (30 °C) for the organisms stores on yam, coco-yam, and cassava. However where the organisms were stored on rice and garri, refrigeration improved the survivability of the organisms by between 10 and 20%.
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  • 20
    ISSN: 1573-0972
    Keywords: Conidia ; cultures ; fermentation ; G. fujikuroi ; morphological ; strains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Strain H-984 of G. fujikuroi grown for 38 h in a shake flask with medium containing 20 g glucose l−1, 3 g yeast extract l−1, 2.5 g NH4NO3 l−1, 0.5 g KH2PO4 l−1, 0.1 g MgSO4 l−1, 1 g CaCO3 l−1, and inoculated into a bioreactor with medium containing 60 g glucose l−1; 1 g NH4Cl l−1; 3 g KH2PO4 l−1 and 1.5 g MgSO4 l−1 produced 1100 mg gibberellic acid l−1.
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  • 21
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    World journal of microbiology and biotechnology 15 (1999), S. 425-430 
    ISSN: 1573-0972
    Keywords: Activity ; fermentation ; HA-1-92 ; isolation ; oxohexaene ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A new antifungal antibiotic, HA-1-92, was isolated from the biomass of Streptomyces CDRIL-312, by extracting in butanol and further purified by silica gel column chromatography followed by preparative TLC. The antibiotic is presumed to be an oxohexaene macrolide and showed promising antifungal activity against yeasts and filamentous fungi including human and plant pathogens. It was found to be less toxic in mice than known oxohexaenes.
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  • 22
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    World journal of microbiology and biotechnology 8 (1992), S. 175-182 
    ISSN: 1573-0972
    Keywords: Cassava ; cyanide ; fermentation ; fu-fu, gari ; lactic acid bacteria ; linamarin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Processes for the production ofgari, East Nigerianfu-fu and West Nigerianfu-fu are described. Changes in pH value, moisture content, microflora and sugar content of cassava duringgari andfu-fu preparation are reported. Mannitol accumulated during thegari fermentation but not in either of thefu-fu fermentations. During each stage ofgari andfu-fu production, lactic acid bacteria predominated. Homofermentative organisms occurred most frequently in the early stages of each process and heterofermenters in the latter ones. Of the 179 microorganisms that were isolated and characterized fromgari andfu-fu, 52% were able to hydrolyse linamarin and 14% starch.
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  • 23
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    World journal of microbiology and biotechnology 8 (1992), S. 284-286 
    ISSN: 1573-0972
    Keywords: Bacillus ; budu ; fermentation ; fish ; proteases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Eight different strains ofBacillus were isolated from fermented fish (Budu) and their proteolytic enzyme activities were determined after 18 h cultivation at room temperature (35° C). Four isolates possessed high protease activities. Optimum pH for these enzymes was between 7.0 and 8.0 and the optimal temperature was 55° C. The proteases retained 40% of their original activity after 20 min at 55° C but lost all activity at 65° C. Three of the four isolates were identified asBacillus subtilis, the fourth asBacillus licheniformis.
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  • 24
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    World journal of microbiology and biotechnology 9 (1993), S. 313-318 
    ISSN: 1573-0972
    Keywords: Cellulose ; eucalyptus wood ; fermentation ; kinetic model ; saccharification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Coupled saccharification and fermentation of Eucalyptus globulus wood, pre-treated by acid hydrolysis and sodium hypochlorite, was carried out in two column reactors: one for enzymatic hydrolysis of the substrate at 50°C and the other for fermentation of sugars with calcium alginate-immobilized Saccharomyces cerevisiae at 30°C. A buffered solution containing cellulases at pH 4.8 was recycled through both reactors. The maximum yields were about 0.26 g ethanol per g of substrate. The results were reproduced reasonably well using a simple kinetic model consisting of two successive pseudo-first-order reactions.
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  • 25
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    World journal of microbiology and biotechnology 8 (1992), S. 71-72 
    ISSN: 1573-0972
    Keywords: Enzymes ; cassava ; fermentation ; ‘fufu’
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Amylase and pectin methyl esterase activities increased rapidly during the early period of the fermentation of cassava for ‘fufu’ production, attaining their peak activities after 12 and 24h, respectively. Cellulase activity was lower and approximately constant for most of the fermentation period.
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  • 26
    ISSN: 1573-0972
    Keywords: Ethanol ; fermentation ; modelling ; molasses ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Batch fermentations of sugar-cane blackstrap molasses to ethanol, using pressed yeast as inoculum, demonstrated an exponential relationship between the time necessary to complete the fermentation and the initial concentrations of sugar and yeast cells. The parameters of the derived exponential equations depended on the experimental conditions.
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  • 27
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    World journal of microbiology and biotechnology 9 (1993), S. 269-274 
    ISSN: 1573-0972
    Keywords: Enterobacteriaceae ; fermentation ; lactic acid bacteria ; maize ; nixtamal ; pozol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Freshly prepared pozol, a traditional Mexican fermented maize dough, contained (c.f.u./g wet wt): lactic acid bacteria, 104 to 106; aerobic mesophiles, 104 to 105; Enterobacteriaceae, 102 to 103; yeasts, 102 to 104; and mould propagules, 〈103. After 30 h at 28°C the numbers were, respectively: 109, 7×106, 5×105, 106 and 104. Soaking alkali-treated grains overnight allowed lactic acid bacteria, aerobic mesophiles and Enterobacteriaceae to grow and these then constituted the primary microbial flora of the pozol dough. Grinding in a commercial mill inoculated the dough with lactic acid bacteria, aerobic mesophiles, Enterobacteriaceae and yeasts. Other processing stages, including the nature of the surface upon which the balls were made, handling of the dough, and air, contributed only minor numbers of microbes compared with the two major sources, soaking and grinding. The pH of pozol fell from an initial value of 7.3 to 4.6 after 30 h incubation at 28°C. The numbers of Enterobacteriaceae and other aerobic mesophilic bacteria remained constant between 11 and 30 h incubation and there was no evidence of the acidic conditions having any lethal effects on these organisms.
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  • 28
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    World journal of microbiology and biotechnology 9 (1993), S. 295-299 
    ISSN: 1573-0972
    Keywords: Bacillus ; Enterococcus ; fermentation ; kinema ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Kinema fermentations of Indian and Canadian No. 1 soybeans by Bacillus sp. DK-W1 and by mixed cultures of Bacillus sp. DK-W1 and Enterococcus faecium DK-C1 were essentially identical. The viable cell count of Bacillus increased from an initial 105 to 1010 c.f.u./g wet wt after 48 h incubation at 37°C. The pH of the fermentation dropped from an initial 6.9 to about 6.4 after 8 h and then rose to 8.6 after 32 h, with a coincident increase in proteolytic activity and ammonia concentration. The fermentations containing E. faecium and Bacillus exhibited a greater initial pH decline and a slightly retarded subseqent increase in pH compared with fermentations with Bacillus only. The presence of E. faecium had no detectable effects on growth of the Bacillus, proteolytic activity, ammonia production or the final pH of the fermentations.
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  • 29
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    World journal of microbiology and biotechnology 9 (1993), S. 603-604 
    ISSN: 1573-0972
    Keywords: Cocoa beans ; fermentation ; microbial populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Acetic and lactic acid bacteria on fermented cocoa beans were maximally 2.0×106 and 1.9×106 c.f.u./g wet wt, respectively. Acetic and lactic acids were detected on the second and fourth days of fermentation and were maximally 140 and 45 mg/10 g beans, respectively. There was a positive correlation between the sizes of the relevant microbial populations and the amounts of acids produced during fermentation.
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  • 30
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    World journal of microbiology and biotechnology 16 (2000), S. 341-344 
    ISSN: 1573-0972
    Keywords: Composite ; fermentation ; finger millet ; skim milk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Fermented composite beverages of finger millet and milk are popular, nutritious, traditional foods in many parts of Zimbabwe. With the aim of commercial production, we determined what type of microbial cultures can be used to ferment a composite finger millet and skimmed milk powder gruel and the optimum conditions for its production. Composites containing between 0 and 100% finger millet gruel by volume were inoculated and incubated at various temperatures. The desired pH of 4.5 or less was obtained with incubation at 30 to 45 °C (but not at lower temperatures) with lower pH values being obtained as the temperature increased. YC380 (a yoghurt type bacterial starter culture) produced a pH of 4.5 or less only when skim milk was also present; V2 (another yoghurt type bacterial starter culture) did so at all levels of finger millet gruel and JC (a mixed strain culture developed to ferment cereals) only when finger millet gruel was present. A clear relationship between incubation temperature and syneresis could not be established but syneresis decreased significantly (p 〈 0.05) with increasing proportions of finger millet gruel. A thick product with a set consistency was obtained with YC380 at an incubation temperature of 45 °C and a storage temperature of 7 °C regardless of proportion of finger millet gruel. V2 produced a thick product with a set consistency at an incubation temperature of 45 °C, and storage temperature of 7 °C and when the proportions of finger millet gruel were between 0 and 50%. It appears that yoghurt type bacterial cultures can be successfully used to produce a composite fermented beverage from finger millet and skim milk, but cultures developed for fermentation of cereals are not suitable.
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  • 31
    ISSN: 1573-0972
    Keywords: Beauveria bassiana ; fermentation ; L-glutaminase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Beauveria sp. BTMF S10 isolated from marine sediment produced extracellular L-glutaminase. Maximal L-glutaminase yield (46.9 U/ml) was obtained in a medium supplemented with 1% (w/v) yeast extract and sorbitol, 9% (w/v) sodium chloride and 0.2% (w/v) methionine, initial pH 9.0 and at 27  °C after 108 h. This enzyme was inducible and growth-associated.
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  • 32
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    World journal of microbiology and biotechnology 13 (1997), S. 619-625 
    ISSN: 1573-0972
    Keywords: Alcohol ; biofuel ; corn fibre ; corn germ ; Escherichia coli ; fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Corn hulls and corn germ meal were both evaluated as feedstocks for production of ethanol for biofuel. Currently, these fibrous co-products are combined with corn steep liquor and the fermentation bottoms (if available) and marketed as cattle feed. Samples were obtained from wet and dry corn mills. The corn hulls and germ meal were evaluated for starch and hemicellulose compositions. Starch contents were 12 to 32% w/w and hemicellulose (arabinoxylans) contents were 23 to 64% w/w. Corn fibrous samples were hydrolysed, using dilute sulphuric acid, into mixed sugar streams containing arabinose, glucose and xylose. Total sugar concentrations in the hydrolysate varied from 8.4 to 10.8% w/v. The hydrolysates were fermented to ethanol using recombinant E. coli strains K011 and SL40. Ethanol yields were 0.38 to 0.41g ethanol produced/g total sugars consumed and fermentations were completed in 60h or less. However, residual xylose was detected for each hydrolysate fermentation and was especially significant for fermentations using strain SL40. Strain K011 was a superior ethanologenic strain compared with strain SL40 in terms of both ethanol yield and maximum productivity.
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  • 33
    ISSN: 1573-0972
    Keywords: Microalgae ; soy sauce waste ; ethanol ; fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The growth of four marine microalgae was examined in a medium prepared from the effluent from the desalting process of soy sauce waste. A strain of Dunaliella that showed abundant growth on soy sauce waste extract was selected, and optimum cultivation conditions were determined. The algal cells produced were disrupted, and saccharified with glucoamylase. The saccharified solution was fermented using Saccharomyces cerevisiae IAM 4140. Stoichiometric study revealed that 11mg of ethanol was produced from 1g (dry cell weight) of Dunaliella cells. This work indicates a new method for removing waste products of the soy sauce production industry.
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  • 34
    ISSN: 1573-0972
    Keywords: Adenosine phosphates ; fermentation ; flor-veil-forming yeast ; nicotinamide adenine dinucleotides ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Significant changes in the intracellular concentrations of adenosine phosphates and nicotinamide adenine dinucleotides were observed during fermentation of grape must by three different strains ofSaccharomyces cerevisiae: S. cerevisiae var.cerevisiae, a typical fermentative yeast strain and two flor-veil-forming strains,S. cerevisiae var.bayanus andS. cerevisiae var.capensis. The intracellular concentration of ATP was always higher inS. cerevisiae var.cerevisiae than in the flor-veil-forming strains. NAD+ and NADP+ concentrations decreased at faster rates in the flor-veil-forming yeasts than in the other yeast but NADH concentration was the same in all yeasts for the first 10 days of fermentation. NADPH concentration was always lower inS. cerevisiae var.cerevisiae than in the other yeasts and this yeast also showed higher rates of growth and fermentation during the early stages of the fermentation and the presence of non-viable cells at the end of fermentation. In contrast, the flor-veil-forming strains maintained growth and fermentation capabilities for a relatively long time and viable cells were present throughout the entire fermentation process (31 days).
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  • 35
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    World journal of microbiology and biotechnology 12 (1996), S. 357-360 
    ISSN: 1573-0972
    Keywords: Ethanol production ; fermentation ; sweet-stem sorghum
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Ethanol tolerance, osmotolerance and sugar conversion efficiency were used to screen yeasts for potential ethanol production from sweet-stem sorghum juice. Of the ten strains of Saccharomyces sp. that produced ethanol from the sorghum juice or from yeast extract/phosphate/sucrose (YEPS) media, the best sugar conversion efficiencies were greater than 85% for the strains Vin7, SB9, N96 and GSL. Vin7 and SB9 had higher sugar conversion efficiencies for sweet-stem sorghum juice, while strains N96 and GSL gave higher conversions in YEPS.
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    World journal of microbiology and biotechnology 12 (1996), S. 7-11 
    ISSN: 1573-0972
    Keywords: Bacillus sphaericus ; biological control ; fermentation ; gene control
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract β-Galactosidase gene fusions have been used to monitor the progress of mosquito-larvicidal-toxin gene expression in Bacillus sphaericus strain 2362. β-Galactosidase estimation in cells from late-growth-phase batch cultures was compared with larvicidal toxicity after incubation for 48 h. Conditions which promoted efficient sporulation, such as plentiful trace elements and relatively crude protein sources (soybean or cottonseed flours), enhanced reporter gene expression and provided high toxicity. However, acetate, which repressed sporulation, similarly repressed binary toxin yield. Gene fusions to the binary and 100-kDa toxin genes of B. sphaericus could be useful for the rapid screening of fermentation conditions for the local production of this larvicidal bacterium but, in view of the poor correlation with toxicity at high toxicity levels, such experiments should be confirmed with bioassays.
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  • 37
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    World journal of microbiology and biotechnology 13 (1997), S. 457-462 
    ISSN: 1573-0972
    Keywords: Cocoa beans ; cocoa sweatings ; fermentation ; yeasts
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Cocoa sweatings, the pale yellowish liquid that drains off during cocoa fermentation, is the breakdown product of the mucilage surrounding the fresh cocoa bean, and constitutes about 10% of the weight of the cocoa fruit. On average, about 1.9 million l of sweatings are produced annually in Ghana during the cocoa harvesting season. It has been shown to be a suitable medium for the production of wines, alcohol, marmalade, jam and syrup. Its rapid collection in high yields and quality is the first step to its utilization on a commercial scale. Thus pure yeast culture fermentation of cocoa under controlled temperature conditions and its effect on yield of sweatings and final cocoa bean quality was investigated. Cocoa fermentations employing Saccharomyces chevalieri or Kluyveromyces fragilis alone gave significantly higher yields of sweatings (p 0.05) than controls. The initial rates of sweating by the two strains were also very high but dropped to a constant minimum value after 12h of fermentation. In contrast, fermentations employing Torulopsis candida or Candida norvengensis alone as well as different combinations of all the yeast strains did not give any significant difference in yield compared to controls (p 0.05). Fermentations using S. chevalieri alone or other combinations in which S. chevalieri was present gave beans with acceptable quality based on different quality indices used for grading cocoa beans commercially.
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  • 38
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    World journal of microbiology and biotechnology 13 (1997), S. 665-670 
    ISSN: 1573-0972
    Keywords: Dissolved oxygen tension ; fermentation ; Fusicoccins ; Fusicoccum amygdali Del
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The regulatory effect of different concentrations of dissolved oxygen on the production of fusicoccins by the fungus Fusicoccum amygdali Del. was studied. The maximum output of total fusicoccins was obtained by using a profiled dissolved oxygen tension (DOT) regime, in which the DOT was maintained at 15–20% during the biomass growth phase and at 5–8% during the fusicoccins production phase. In comparison with the profiled regime, the maintenance of DOT at 15–20% during the whole fermentation shortened the fusicoccins production phase. The fermentation performance at a low DOT (5–8%) inhibited both the accumulation of biomass and the production of fusicoccins. At high DOT (40–50%), an accelerated accumulation of the biomass with an expressed autolysis of mycelia took place, and the production of fusicoccins was lowered. The qualitative composition of individual fusicoccins varied substantially at different DOTs. Fusicoccins, A, C, D, J, H, 16-O-demethyl-J, detretpentenylfusicoccin and some minor fusicoccin metabolites were found in the fermentation broth using the method of liquid secondary ion mass spectrometry. It was established that the profiled DOT regime (15–20% to 5–8%) provided both the maximum concentration of fusicoccins and an enhanced accumulation of the main metabolite – fusicoccin A (FC A). The performance of the fermentation at a DOT of 15–20% decreased the content of FC A by 2–6% in comparison with the profiled DOT regime, and increased the content of fusicoccin C to 14–20% of the total fusicoccins. Fermentation at DOT of 5–8% was characterized by the highest content of the precursors of FC A, the less oxidized fusicoccins H and J, the contents of which were in range 7–12% and 16–17% of total fusicoccins, respectively.
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  • 39
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    World journal of microbiology and biotechnology 14 (1998), S. 451-456 
    ISSN: 1573-0972
    Keywords: Aroma ; fermentation ; starter cultures ; uji ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Three methods for fermentation of uji were compared in laboratory trials: spontaneous, backslopping (using an inoculum from a previous fermentation) and use of a starter culture of lactic acid bacteria. Spontaneous fermentation resulted in the slowest decrease in pH, while the use of starter culture led to the lowest final pH (3.5). Coliforms were eliminated in less than 8 h using backslopping or starter culture, but increased in numbers during spontaneous fermentation. The viscosity of uji was only marginally affected by the method of fermentation. The aroma profile following spontaneous fermentation contained esters with fruity notes and ethanol and higher alcohols, while mainly organic acids was produced by fermentation with the starter culture. Backslopping led to the lowest production of almost all volatiles identified.
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  • 40
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    Journal of industrial microbiology and biotechnology 15 (1995), S. 49-54 
    ISSN: 1476-5535
    Keywords: antibiotic ; fermentation ; microbial transformation ; hydroxylation ; aurodox ; heneicomycin ; Streptomyces goldiniensis ; Streptomyces filippiniensis
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Streptomyces sp GE44282 was isolated in the course of a screening program for novel antibiotics. It co-produces heneicomycin and aurodox, two kirromycin-type antibiotics, which differ by the presence of an hydroxyl group at the C30 position of aurodox. Heneicomycin is converted into aurodox both by growing and resting cells ofStreptomyces sp GE44282 and by the producer of aurodox,Streptomyces goldiniensis ATCC 21386. This bioconversion of heneicomycin is substrate-specific and is not observed using the producer of heneicomycin,Streptomyces filippiniensis NRRL 11044. The three strains show very similar taxonomic characteristics. These results suggest that heneicomycin is a precursor of aurodox, the production of which depends on the bioconversion capability expressed by the strain.
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    Journal of industrial microbiology and biotechnology 15 (1995), S. 414-417 
    ISSN: 1476-5535
    Keywords: fermentation ; scale up ; secondary metabolite ; physostigmine
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    Notes: Abstract A reliable and scalable fermentation process was developed for production of the acetylcholine esterase inhibitor physostigmine employingStreptomyces griseofuscus NRRL 5324. Initial fermentation in small-scale bioreactors reached physostigmine levels of approximately 60 mg L−1 after 139 h. Optimization of both process operating parameters and production medium composition rapidly yielded a seven-fold increase in physostigmine titer. The scaled up process routinely produced physostigmine titers of approximately 400 mg L−1 during a fermentation cycle of 180 h, and supported the rapid production of large amounts of physostigmine. A physostigmine production of 500 mg L−1 representing an eight-fold improvement over the original performance, was achieved using a glucose/ammonium fed-batch process.
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  • 42
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    Journal of industrial microbiology and biotechnology 15 (1995), S. 442-445 
    ISSN: 1476-5535
    Keywords: Zymomonas mobilis ; ethanol ; proteolipid ; fermentation
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Zymomonas mobilis produces more than three times as many colony-forming units when grown in the presence of a combination of protein and lipid medium supplements than in unsupplemented cultures. The specific ethanol production rate is twice as fast, and the percent yield is higher (92% vs 82%), in supplemented than in unsupplemented broth. In addition, there is a change in the phospholipid composition of cells grown in the presence of supplements. Both materials are required for enhancement of fermentation and growth.
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  • 43
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    Journal of industrial microbiology and biotechnology 16 (1996), S. 374-376 
    ISSN: 1476-5535
    Keywords: soy ; hydrolysate ; nutrient ; fermentation ; ethanol ; amino acids
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An optimized soy-based medium was developed for ethanol production byEscherichia coli KO11. The medium consists of mineral salts, vitamins, crude enzymatic hydrolysate of soy and fermentable sugar. Ethanol produced after 24 h was used as an endpoint in bioassays to optimize hydrolysate preparation. Although longer fermentation times were required with soy medium than with LB medium, similar final ethanol concentrations were achieved (44–45 g ethanol L−1 from 100 g glucose L−1). The cost of materials for soy medium (excluding sugar) was estimated to be $0.003 L−1 broth, $0.006 L−1 ethanol.
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  • 44
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    Journal of industrial microbiology and biotechnology 16 (1996), S. 102-109 
    ISSN: 1476-5535
    Keywords: Millet ; Pennisetum typhoides ; liquefaction ; saccharification ; baker's yeast ; Saccharomyces cerevisiae ; fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A fermentation medium based on millet (Pennisetum typhoides) flour hydrolysate and a four-phase feeding strategy for fed-batch production of baker's yeast,Saccharomyces cerevisiae, are presented. Millet flour was prepared by dry-milling and sieving of whole grain. A 25% (w/v) flour mash was liquefied with a thermostable 1,4-α-d-glucanohydrolase (EC 3.2.1.1) in the presence of 100 ppm Ca2+, at 80°C, pH 6.1–6.3, for 1 h. The liquefied mash was saccharified with 1,4-α-d-glucan glucohydrolase (EC 3.2.1.3) at 55°C, pH 5.5, for 2 h. An average of 75% of the flour was hydrolysed and about 82% of the hydrolysate was glucose. The feeding profile, which was based on a model with desired specific growth rate range of 0.18–0.23 h−1, biomass yield coefficient of 0.5 g g−1 and feed substrate concentration of 200 g L−1, was implemented manually using the millet flour hydrolysate in test experiments and glucose feed in control experiments. The fermentation off-gas was analyzed on-line by mass spectrometry for the calculation of carbon dioxide production rate, oxygen up-take rate and the respiratory quotient. Off-line determination of biomass, ethanol and glucose were done, respectively, by dry weight, gas chromatography and spectrophotometry. Cell mass concentrations of 49.9–51.9 g L−1 were achieved in all experiments within 27 h of which the last 15 h were in the fedbatch mode. The average biomass yields for the millet flour and glucose media were 0.48 and 0.49 g g−1, respectively. No significant differences were observed between the dough-leavening activities of the products of the test and the control media and a commercial preparation of instant active dry yeast. Millet flour hydrolysate was established to be a satisfactory low cost replacement for glucose in the production of baking quality yeast.
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  • 45
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    Journal of industrial microbiology and biotechnology 15 (1995), S. 424-428 
    ISSN: 1476-5535
    Keywords: Clostridium thermoaceticum ; fermentation ; acetic acid ; calcium magnesium acetate ; corn steep liquor ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A low-cost nutrient medium based on corn steep liquor (CSL) was developed for the production of acetates byClostridium thermoaceticum. Pre-treatment of CSL with dolime and vitamin supplementation increased the rate of acetate production. Adding excess nutrients in a fed-batch mode minimized by-product formation and increased final acetate concentration from 19 g L−1 to 40 g L−1 acetic acid. High yields of acetic acid (0.95 g g−1 glucose in fed-batch mode) was probably due to the conversion of the lactic acid in CSL into acetic acid by the organism.
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  • 46
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    Keywords: fermentation ; fermentation monitoring ; fermentation control ; fermentation software ; Escherichia coli
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    Notes: Abstract The advent of inexpensive computers and associated control and data acquisition software makes possible the development of sophisticated, configurable, integrated monitoring and control systems for small-scale laboratory and pilot-scale fermentors at low cost. We describe here the implementation of such a system, the interfacing of off-line instruments to enhance real time data analysis, low level process control and several substrate feeding protocols.
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  • 47
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    World journal of microbiology and biotechnology 11 (1995), S. 491-493 
    ISSN: 1573-0972
    Keywords: Acidity ; fermentation ; Kunun-zaki ; lactobacilli ; microflora ; millet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract ‘Kunun-zaki’ is a beverage produced by a fermentation process involving the steeping of millet grains and wetmilling. Initially, there is a wide range of microflora but, after steeping, the moulds are eliminated, leaving a 1:1 ratio of Gram-negative bacteria to Gram-positive bacteria. By the end of the fermentation, all Gram-negative bacteria are eliminated and Lactobacillus spp. predominate. Increase in acidity during the process also encourages growth of Saccharomyces cerevisiae. Fermentation for 8 h produces an acceptable product.
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    World journal of microbiology and biotechnology 12 (1996), S. 47-49 
    ISSN: 1573-0972
    Keywords: Bacteria ; fermentation ; flour ; microalgal biomass ; potato ; rye ; wheat
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The marine microalga Phaeodactylum tricornutum was cultivated in semi-continuous culture under mixotrophic conditions with the soluble fractions of potato, rye and wheat flours that had been naturally fermented, at 2% or 4% (w/v). The rye flour produced the highest microalgal cellular density of 90×106 cells.ml-1 when supplemented with NaNO3 and NaH2PO4. The autotrophic control only gave 57×106 cells.ml-1. The value of agricultural surpluses, such as rye flour, can therefore be increased by its use in the production of valuable, microalgal biomass which is rich in protein, pigments and fatty acids.
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  • 49
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    World journal of microbiology and biotechnology 12 (1996), S. 82-84 
    ISSN: 1573-0972
    Keywords: Biosurfactants ; critical micellar concentration ; fermentation ; haemolytic capacity ; surface tension
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Haemolysis has been used as an initial selection criterion for the primary isolation of surfactant-producing bacteria. Only 37 of 492 strains of different origins had haemolytic activity. These 37 strains, together with 49 non-haemolytic ones chosen at random, were studied for surface activity. Only five strains, all of them haemolytic, tested positive. Haemolysis and biosurfactant-production are thus probably associated.
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  • 50
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    World journal of microbiology and biotechnology 12 (1996), S. 53-56 
    ISSN: 1573-0972
    Keywords: Cassava ; fermentation ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The major genera found in the microflora of fermented, sour, cassava-starch were Streptococcus, Bacillus, Lactobacillus and Saccharomyces with amylase activity. Lactic acid bacteria predominated whereas the presence of moulds was not significant. No coliforms were detected. Electron microscopy showed bacteria and yeasts in contact with the starch granules and signs of erosion on the granule surface. Lactic acid was the main metabolite; no oligosaccharides, maltose or glucose were detected, indicating their rapid utilization. The degree of acidification, which correlated with the decrease in viscosity and the final quality of the product, was influenced by the variable microbial ecology.
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    World journal of microbiology and biotechnology 14 (1998), S. 689-691 
    ISSN: 1573-0972
    Keywords: Amycolatopsis mediterranei ; fermentation ; media design ; rifamycin production
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract The fermentative production of rifamycin by Amycolatopsis mediterranei (MTCC17) has been studied. Both qualitative and quantitative aspects of the fermentation were determined by optimizing cultural conditions and medium design to improve the production of rifamycin. A pH value of 7.0, a temperature of 26°C, an aeration rate of 250rev/min for a 50ml volume, a level of inoculum of 10% grown aeration for 48h and a fermentation period of 11days were found to be optimum. Among the nitrogen sources, and culture conditions, peanut meal and aeration were found to be critical for rifamycin production respectively. The above mentioned exercise increased the yields of rifamycin from 350mg/l to 2000mg/l.
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  • 52
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    Biotechnology and Bioengineering 38 (1991), S. 831-837 
    ISSN: 0006-3592
    Keywords: fermentation ; Escherichia coli ; recombinant fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of dilution rates on the performance of a two-stage fermentation system for a recombinant Escherichia coli culture were studied. Dilution rate determines the apparent or averaged specific growth rate of a heterogeneous population of cells in the recombinant culture. The specific growht rate affects the genetic parameters involved in product formation in the second stage, such as plasmid stability, plasmid content, and specific gene expression rate. Kinetic models and correlations were developed for these parameters based on experimental data. Simulations of plasmid stability in the first stage showed that for longer fermentation periods, plasmid stability is better at higher dilution rates. However, the plasmid content is lower at these dilution rates. The optimal apparent specific growth rate for maximum productivity in the second stage was determined using two methods: (1) direct search for a constant specific growth rate, and (2) dynamic optimization using the maximum principle for a time-dependent specific growth rate profile. The results of the calculations showed that the optimum constant apparent specific growth rate for maximum over-all productivity is 0.40 h-1. This coincides with the optimal specific growht rate for maximum plasmid content in the expressed stage. A 3.5% increase in overall productivity can be obtained by using a linear time dependent apparent specific growth rate control, μ2(t) = 0.0007t, in the course of the fermentation time.
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  • 53
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    Biotechnology and Bioengineering 38 (1991), S. 1034-1040 
    ISSN: 0006-3592
    Keywords: amino acid fermentation ; culture redox potential ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We investigated the relationship of dissolved oxygen and culture redox potential (CRP) on amino acid production. Corynebacterium glutamicum ATCC 14296 was used for all experiments. The fermentation can be divided into a growth phase and a production phase. Our results indicate that in order to get higher amino acid production, a lower oxygen supply during the exponential phase is favored. A higher oxygen supply rate appears to be necessary during the production phase. Culture redox potential (CRP) was used to monitor the fermentation. CRP readings were observed to drop to a characteristic minimum value as the metabolic state changed from a growth to production phase. This was evidenced by the commencement of amino acid production and a simultaneous uptake of lactate. Upon lactate exhaustion, the CRP increased abruptly. At the same time, maximal amino acid yields were observed. By the use of minimum CRP as an indication of metabolic phase changes, the agitation rate was changed to increase oxygen supply during the production phase. This significantly increased amino acid production. These results show that culture redox potential measurements can be used to monitor and optimize amino acid production by process manipulation.
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    Biotechnology and Bioengineering 39 (1992), S. 365-368 
    ISSN: 0006-3592
    Keywords: fermentation ; adsorption ; lactic acid ; fluidized bed ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A bioreactor configuration is proposed for simultaneous fermentation and separation of the desired product. The bioreactor consists of a columnar fluidized bed of immobilized microorganisms. Denser adsorbent particles are added to this column. These adsorbent particles fall through the bed, absorb the product, and are removed from the base of the columnar reactor. The system hydrodynamics and the separability of the two types of particles were confirmed for low-density gel beads. The addition of the adsorbent, activated carbon, to a fermentation of Lactobacillus delbreuckii absorbed lactic acid. The addition of adsorbent enhanced the fermentation and controlled the pH.
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    Biotechnology and Bioengineering 39 (1992), S. 732-740 
    ISSN: 0006-3592
    Keywords: cell disruption ; chemical permeabilization ; Escherichia coli ; fermentation ; protein recovery ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Overall protein release greater than 75% in less than 1 h can be attained by exposing exponentially growing Escherichia coli cells to 0.4 M guanidine plus 0.5% Triton X-100 at 37°C in medium. Cell growth stops immediately upon addition of the chemicals, but the cells are not lysed. Guanidine concentrations lower than 0.2 M, in conjunction with 0.5% Triton X-100, do not release significant intracellular protein, nor do they inhibit cell growth. Under these conditions, the cells undergo an adaptation that confers resistance to protein release by further treatment with guanidine and Triton X-100. Cells treated with 0.2 M guanidine plus 0.5% Triton X-100 display intermediate behavior. Protein release is approximately 35%, and growth is temporarily interrupted by an extended lag phase. Subsequent resumption of cell growth results in resistant cells and no additional protein release. This resistance is shown to be reversible and is most likely due to physiological adaptation rather than genetic mutation.
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    Biotechnology and Bioengineering 39 (1992), S. 1151-1160 
    ISSN: 0006-3592
    Keywords: fluorescence ; monitoring ; methane ; fermentation ; NAD(P)H ; F420 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On-line in situ fluorescence measurements of the methanogenic fermentation were conducted with reactors receiving either glucose or a mixture of volatile fatty acids as the substrate. The reactors were perturbed from steady-state conditions in order to assess the response of fluorescencemonitoring probes. Two fluorescence-monitoring probes were evaluated over a period of 8 months; they performed in a consistent manner, and their response was not significantly affected by the changes in pH and redox potential encountered during routine reactor operation. A commercially available probe, designed to measure NAD(P)H, demonstrated particular promise for detecting imbalance caused by the entry of air, inhibitor addition and was capable of distinguishing between different substrates. This fluorescence-monitoring probe detected imbalance more rapidly than other on-line measurements such as pH, Eh, or gas production, or off-line measurements such as volatile fatty acid concentration or gas composition. An experimental fluorescence-monitoring probe, designed to measure coenzyme F420, also showed some promise in this regard. The response of the fluorescence-monitoring probes also revealed details of the metabolic routes in the reactors and the probes represent a useful research tool. For example, a failure to observe the characteristic response of the NAD(P)H-monitoring probe to formate addition during the metabolism of acetate, propionate, or glucose strongly suggests that any formate liberated during their catabolism is degraded via a different route to exogenously added formate.
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    Biotechnology and Bioengineering 40 (1992), S. 1309-1318 
    ISSN: 0006-3592
    Keywords: Saccharomyces cerevisiae ; fermentation ; cell wall ; surface electrochemistry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cell-wall properties of three strains of the yeast Sacharomyces cerevisiae have been experimentally studied at various times during fermentation. The cell walls have been characterized by electrophoretic mobility measurements, from which zeta potentials may be calculated. They have also been characterized by computerized pH titration, which gives direct information on the number and nature of groups in the yeast cell wall. The data have been quantitatively analyzed in three ways. First, a simplified analysis of the electrokinetic data of a type used by previous workers has been applied. Second, such a simplified analysis of the electrokinetic data has been developed more rigorously by means of a two-dimensional site-dissociation model of the outer cell wall-solution interface. Third, a description of the yeast cell-wall electrochemical properties in terms of a three-dimensional gel model incorporating site dissociation has been developed. The advantages and disadvantages of the three analyses are discussed. Only the three-dimensional gel model can account simultaneously for both the electrokinetic and pH surface titration data. It provides new insights into the changes that occur to the yeast cell wall during fermentation. © 1992 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 37 (1991), S. 703-707 
    ISSN: 0006-3592
    Keywords: Dextransucrase ; Leuconostoc mesenteroides ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: High yields of the enzyme dextransucrase have been produced repeatedly by fed-batch fermentation techniques. Activities in excess of 21.9 U/cm3 have been obtained by culturing Leuconostoc mesenteroides NRRL B-512(F) under nonaerated fed-batch fermentation conditions. Aerobic fermentations carried out under identical conditions have consistently produced enzyme of less than 17 U/cm3, but with no difference in the final cell concentration in the broth. Different types of yeast extract have been found to have significant effect on the final cell concentration and more especially on the enzyme activity with enzyme yields varying by as much as 50% when different types of yeast extracts were used.
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    Biotechnology and Bioengineering 40 (1992), S. 634-637 
    ISSN: 0006-3592
    Keywords: mass spectrometer ; fermentation ; oxygen uptake rate ; noise ; bias ; filter ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The calculation of many derived fermentation variables such as the respiratory quotient (RQ) and mass transfer coefficient (KLa) requires the differences between the molar percentages of oxygen and carbon dioxide in the fermentor inlet and exit gas, called the %OUR and %CER. Noise and bias in %CER data is of order that in the exit gas carbon dioxide analysis. However, the relative amount of noise in the %OUR is one to two orders of magnitude greater than the noise in the raw oxygen analyses because the %OUR is calculated as a small difference between two large quantities. The noise in the %OUR is white with a Gaussian amplitude probability distribution of absolute standard deviation 0.0145. A chi-square filter of the %OUR data is shown to considerably improve the quality of the calculated RQ and KLa for a fermentation of Streptomyces clavuligerus. © 1992 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 38 (1991), S. 304-313 
    ISSN: 0006-3592
    Keywords: Zymomonas mobilis ; molasses ; fermentation ; ethanol ; osmolality ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new osmotolerant mutant strain of Zymomonas mobilis was successfully used for ethanol production from beet molasses. Addition of magnesium sulfate to hydrolyzed molasses allowed repeated growth without the need of yeast extract addition. The kinetics and yields parameters of fermentation on media with different molasses concentrations were calculated. The anabolic parameters (specific growth rate, μ, and biomass yield, YX/S) were inhibited at elevated molasses concentrations while the catabolic parameters (specific ethanol productivity, qp, and ethanol yield, Yp/s) were not significantly affected. In addition to ethanol and substrate inhibition, osmotic pressure effects can explain the observed results.
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    Biotechnology and Bioengineering 38 (1991), S. 353-362 
    ISSN: 0006-3592
    Keywords: Rhizopus oligosporus ; fermentation ; starch ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Semimechanistic mathematical model is developed which describes the growth of Rhizopus oligosporus in a model solid-state fermentation system. Equations are presented for the release of glucoamylase, the diffusion of glucoamylase, the hydrolysis of starch, the generation and diffusion of glucose, and the uptake of glucose and conversion into new biomass. Good agreement of the model with the experimental data was obtained only after the glucoamylase diffusivity and the maximum specific glucose uptake rate were altered from their originally determined values. The model recognizes the distributed nature of the solid-state fermentation and therefore is able to predict the concentration profiles of the system components within the substrate. The model provides an insight into the possible rate-limiting steps in solid-state fermentation - the generation of glucose within the substrate and the resulting availability of glucose at the surface.
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  • 62
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    Biotechnology and Bioengineering 42 (1993), S. 1190-1198 
    ISSN: 0006-3592
    Keywords: fermentation ; bioprocess monitoring ; bioluminescence ; inner filter effect ; Escherichia coli ; cell concentration monitoring ; fiber optic ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bioluminescence has recently become a popular research tool in several fields, including medicine, pharmacology, biochemistry, bioprocessing, and environmental engineering. Beginning with purely qualitative goals, scientists are now targeting more demanding applications where accurate, quantitative interpretation of bioluminescence is necessary. Using the recent advances in fiber-optic technology, bioluminescence is easily monitored in vivo and in real time. However, the convenience of this measurement is often concealing an unsuspected problem: the bioluminescence signal might be corrupted by a large error caused by the extinction of light by biological cells. Since bioluminescent cultures not only emit light but also absorb and scatter it, the measured signal is related in a complex, nonlinear, and cell-concentration-dependent manner to the “true” bioluminescence. This light extinction effect, known as the “inner filter effect,” is significant in high-density cultures. Adequate interpretation of the bioluminescence signal can be difficult without its correction. Here, we propose a real-time algorithm for elimination of the inner filter effect in a bioreactor. The algorithm yields the bioluminescence which would be measured if the glowing culture was completely transparent. This technique has been successfully applied to batch and continuous cultivation of recombinant bioluminescent Escherichia coli. © 1993 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 41 (1993), S. 148-155 
    ISSN: 0006-3592
    Keywords: plasmid stability ; Streptomyces lividans ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Plasmid plJ303 stability in Streptomyces lividans cultures has been studied by measuring plasmid copy number under various growth conditions. An increase in mean plasmid copy number was normally seen during early rapid growth in both shaken culture and stirred vessel fermentations at 28°C. Maximum copy numbers were consistently attained in early stationary phase followed by a decline (of variable amount) upon further incubation. The imposition of environmental stress (high growth temperature, i.e., 37°C, and low dissolved oxygen tension, i.e., 〈5% air saturation) led to a plasmid copy number of zero and a 50% reduction, respectively. Interestingly, the relative proportions of plasmid topoisomers changed with time since progressively more supercoiled forms were observed throughout the stationary phase. Plasmid dimers were also observed in some cultures, and no evidence of structural plasmid instability was found. In general, this host-vector system seemed remarkably stable under normal growth conditions. However, copious organic acid production by the host was observed and was thought to be undesirable for good heterologous gene expression of a secreted protein. © 1993 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 44 (1994), S. 539-548 
    ISSN: 0006-3592
    Keywords: cross-flow filtration ; Escherichia coli ; cell harvesting ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cross-flow filtration of Escherichia coli strains was examined at the laboratory and pilot scales using Romicon 500,000 molecular-weight-cutoff hollow fiber membranes. Both the series resistance and macrosolute polarization models were employed to compare performances. Total dissolved solids content above 90 g/L and viscosity above 1.1 × 10-3 paċ s of cell-free culture media were found to decrease average filtration fluxes by over 60% both in the absence and presence of cells. Broth filtration with culture media of dissolved solids levels below 80 g/L were influenced to a greater extent by harvest cell density. The collodial nature of the complex nutrient responsible for the total solids increase affected prediction of filtration performance. Differences in strain filterability were observed with JM109 preferred over DH5 in high solids-containing media and RR1 preferred over JM109 in low dissolved solids-containing media. Their research demonstrates the importance of cell strain and media selection in the performance of early downstream processing steps. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 44 (1994), S. 21-28 
    ISSN: 0006-3592
    Keywords: cell recycle ; thermophilic ethanol fermentation ; Bacillus ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Continuous fermentation with cell recycle proved very effective in increasing the ethanol volumetric productivity of the thermophilic facultative anaerobe, Bacillus stearothermophilus strain LLD-15, on sucrose at 70°C. When complete cell recycle was used, cell viability decreased after a few residence times and sucrose consumption was reduced. Operation using a constant bleed rate resulted in greater stability and higher ethanol volumetric productivities. A mathematical model based on maintenance energy requirements provided an adequate description of the system. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 44 (1994), S. 87-94 
    ISSN: 0006-3592
    Keywords: glutamic acid ; fermentation ; fuzzy control system ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: In glutamic acid fermentation, the molasses feeding policy and time of penicillin addition significantly affected glutamic acid production, and a fuzzy supervisory control system was developed for their quasi-optimal regulation.From the trend of the experimental data, production rules and membership functions of fuzzy inference were devised to determine the quasi-optimum molasses feeding policy and penicillin addition time. A computer with multitasking operating system was used for the construction of the control system with fuzzy inferencing, which decided the control policy every minute, and the feed rate was controlled automatically. The pattern of residual sugar concentration was almost the same as that of maximum glutamic acid production under manual operation. Using the computer control system, stable production was maintained at the highest level of 71 to 75 g/L. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 43 (1994), S. 483-489 
    ISSN: 0006-3592
    Keywords: microbial fermentation control ; neural network simulation ; backpropagation ; network topology design ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article discusses the development of a prototype neural network-based supervisory control system for Bacillus thuringiensis fermentations. The input pattern to the neural network included the type of inoculum, operation temperature, pH value, accumulated process time, optical density in fermentation medium, and change in optical density. The output from the neural network was the predicted optical density for the next sampling time. The control system has been implemented in both a computer simulation and a laboratory fermentation experiment with promising results. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 44 (1994), S. 1271-1278 
    ISSN: 0006-3592
    Keywords: fermentation ; state estimation ; kalman filter ; multirate systems ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article discusses issues related to estimation and monitoring of fermentation processes that exhibit endogenous metabolism and time-varying maintenance activity. Such culture-related activities hamper the use of traditional, software sensor-based algorithms, such as the extended kalman filter (EKF). In the approach presented here, the individual effects of the endogenous decay and the true maintenance processes have been lumped to represent a modified maintenance coefficient, mc. Model equations that relate measurable process outputs, such as the carbon dioxide evolution rate (CER) and biomass, to the observable process parameters (such as net specific growth rate and the modified maintenance coefficient) are proposed. These model equations are used in an estimator that can formally accommodate delayed, infrequent measurements of the culture states (such as the biomass) as well as frequent, culture-related secondary measurements (such as the CER). The resulting multirate software sensor-based estimation strategy is used to monitor biomass profiles as well as profiles of critical fermentation parameters, such as the specific growth for a fed-batch fermentation of Streptomyces clavuligerus. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 44 (1994), S. 165-169 
    ISSN: 0006-3592
    Keywords: penicillin ; fermentation ; media ; degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Industrial production of penicillin there is a noticeable loss of the product through degradation reactions. It is shown that the degradation of penicillin-V, both in a complex and in a chemically defined medium, can be separated into a phosphate-catalyzed conversion of penicillin-V to penicilloic-V acid, overlaid by at least one other reaction in which penicillin V is degraded to as yet unknown products. Parameter values for the phosphatecatalyzed degradation are found to be independent of the type of fermentation medium. The rate of formation of other degradation products of penicillin-V is found to be significantly higher in a complex fermentation medium with corn-steep liquor in a chemically defined medium. © 1994 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 48 (1995), S. 12-16 
    ISSN: 0006-3592
    Keywords: hexopyranoside:cytochrome c oxidoreductase ; disaccharide oxidation ; oxidation ; kinetic model ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Disaccharides were microbaially transformed to their corresponding 3-keto-derivatives by resting cells of Agrobacterium tumefaciens NCPPB 396. The kinetics and yield of this highly specific oxidation depend on several factors. The oxygen concentration especially has a major influence on the production of 3-keto-derivatives and was investigated kinetically with respect to low stationary oxygen concentrations in solution. Experiments showed unconventional results that conflicted with normal Michaelis-Menten kinetics. A kinetic model was developed and the kinetic constants were calculated. The model and experimental data for sucrose, maltose, iso-maltulose (palatinose), and leucrose are in good agreement with each other. Initial reaction rates with different sugars using constant oxygen concentrations resulted in a Michaelis-Mentent type function. The complete kinetics, including the effect of disaccharide and oxygen concentrations, are presented. © 1995 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 48 (1995), S. 631-638 
    ISSN: 0006-3592
    Keywords: Saccharomyces cerevisiae ; fermentation ; on-line simulation ; state estimation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to study and control fermentation processes, indirect on-tine measurements and mathematical models can be used. In this article we present a mathematical on-line model for fermentation processes. The model is based on atom and partial mass balances as well as on equations describing the acid-base system. The model is brought into an adaptive form by including transport equations for mass transfer and unstructured expressions for the fermentation kinetics. The state of the process, i.e., the concentrations of biomass, substrate, and products, can be estimated on-line using the balance part of the model completed with measurement equations for the input and output flows of the process. Adaptivity is realized by means of on-line estimation of parameters in the transport and kinetic expressions using recursive regression analysis. These expressions can thus be used in the model as valid equations enabling prediction of the process. This makes model-based automation of the process and testing of the validity of the measurement variables possible. The model and the on-line principles are applied to a 3.5-L laboratory tormentor in which Saccharomyces cerevisiae is cultivated. The experimental results show that the model-based estimation of the state and the predictions of the process correlate closely with high-performance liquid chromatography (HPLC) analyses. © 1995 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 53 (1997), S. 372-378 
    ISSN: 0006-3592
    Keywords: glucose ; lactate ; on-line monitoring ; mammalian cell culture ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On-line monitoring and control of cell culture fermentation is important for optimal and consistent production of biologicals. In this work, glucose and lactate concentrations are monitored on-line using a commercially available analyzer (Model 2700, Yellow Springs Instruments, Yellow Springs, OH) during batch and perfusion hybridoma cell fermentation. Cell free samples from the reactor are obtained using a 0.45 μm hollow fiber filtering system placed in a circulation loop. The samples were analyzed at specified times and the data are collected on a computer. A process control strategy was developed to control the concentrations of glucose and lactate in a perfusion reactor where the feed rate is adjusted to maintain their concentrations at desired set points. Hybridoma cells (A10G10) were cultivated in a high density perfusion culture where cell density increased from 2 to 14 million cells/mL. During this period the control algorithm successfully adjusted the perfusion rate while maintaining constant glucose and lactate concentrations. Glucose consumption and lactate accumulation rates as well as net lactate yield on glucose were monitored continuously during perfusion culture. These metabolic rates were observed to be independent of cell concentration and were used for the estimation of viable cell density in the reactor. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 372-378, 1997.
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    Biotechnology and Bioengineering 39 (1992), S. 607-613 
    ISSN: 0006-3592
    Keywords: lactic acid ; Lactobacillus delbreuckii ; extractive ; fermentation ; product inhibition ; packed-column and ion-exchange resin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lactic acid fermentation is an end-product-inhibited reaction. The restriction imposed by lactic acid on its fermentation can be avoided by extractive fermentation techniques. Studies were performed by attaching an ion-exchange resin packed column with a 2-L fermentor for separation of lactic acid. The fermentation, in a conventional batch mode, resulted in a lactic acid yield of 0.828 g · g-1 and a lactic acid productivity of 0.313 g · L-1 · h-1. However, these could be further enhanced to 0.929 g · g-1 and 1.665 g · L-1 · h-1 by extractive fermentation techniques. The effect of temperature on extractive fermentation was remarkable and has been included in this work.
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    Biotechnology and Bioengineering 39 (1992), S. 815-827 
    ISSN: 0006-3592
    Keywords: Penicillium roquefortii ; sporulation ; solid substrate ; fermentation ; buckwheat ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When Pencillium roquefortii is grown on two kinds of buckwheat, exhibiting a low [0.85 g water/g dry matter (DM), buckwheat A] and a high [1.5 g water/g initial dry matter (IDM), buckwheat B] water content, a marked difference in the mode of development of the fungus is observed. Material balances for buckwheat A show that growth does not stop because of nutrient exhaustion. Analysis of water balance shows that active growth proceeds with a permanent limitation by the turgor potential which disappears when the water activity of the substrate is close to 0.96, thus arresting growth. This limitation causes intensive water excretion from the system due to the lowering of the water activity of the substrate. The water content of the mycelium thus decreases from 79% at the beginning of the cultivation to 74% when the growth stops. This is linked to a substantial oxidative metabolism and a high sporulation efficiency, close to 0.85. The spores obtained have a low dry weight and a reduced nitrogen content. In the case of buckwheat B, the active growth is shown to stop because of available mineral nitrogen depletion. No significant decrease in the water activity of the substrate is found during the protein synthesis, and the turgor potential remains high at the end of this period. Culture proceeds with new wall synthesis; the sporulation efficiency remains high and the spores obtained exhibit a high dry weight and a high nitrogen content. The bioenergetic balances show that the P/O ratio varies with the kind of substrate used; its value is close to 1.56 for the low water medium and to 2.21 for the high one. The ATP yield Z is always close to 1, and fungal development occurs with limitations of both anabolism and catabolism on buckwheat B and only of anabolism and catabolism on buckwheat B and only of anabolism on buckwheat A.
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    Biotechnology and Bioengineering 40 (1992), S. 334-336 
    ISSN: 0006-3592
    Keywords: sampling, automatic containment ; Escherichia coli ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A containment sampling system for shake flasks and fermentors has been developed from a blood collection system used in hospitals. The core of the system is a collection vial with a vacuum inside. When a needle connected to the fermentation fluid penetrates a rubber seal on the vial, a sample is withdrawn. The system has been developed in two versions, a manual method for shake flasks, and an automated version for fermentors including cool storage of samples. The sampling system offers the same safety for fermentation containment as the original system offers safety for patients and hospital staff. © 1992 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 39 (1992), S. 293-304 
    ISSN: 0006-3592
    Keywords: control ; fermentation ; baker's yeast ; high cell density ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A methodology for the design and evalution of bioprocess control strategies is presented. The strategies manage nutrient supply with demand and vary with the metabolic condition and phase of fermentation operation. Six carbon source addition strategies are based on different combinations of available measurements; they are described and evaluated under different operating conditions for yeast cultivation. It is concluded that a single control strategy is not the most appropriate under all possible operating conditions. An oxygen uptake rate-based control strategy performs better with a mean respiratory quotient (RQ) value less than 1.1 during an oxygen limitation than an ethanol control strategy which had a mean RQ of 14. The designed strategies and an approach of applying the strategy that best matches fermentation conditions consistently enables achievement of high cell densities 78.7 g DCW/L and yields 0.50 g DCW/g glucose as the mean values for three fermentations.
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    Biotechnology and Bioengineering 40 (1992), S. 875-888 
    ISSN: 0006-3592
    Keywords: cell concentration ; light scatter ; solid substrate ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel sensor was developed, based on light scatter, to estimate the cell concentration in the presence of suspended solids. The light scatter properties of cells in the presence of suspended solids were investigated. Two crucial observations were made: first, that the light scatter from cells is essentially a linear function of cell concentration and, second, that invariant regions are present in the light scatter spectrum of cell/solid substrate mixtures. Invariant regions are wavelength intervals of the light scatter spectrum in which the light scatter reading is independent of solid substrate concentration and only a function of cell concentration. The occurrence of invariant regions is the key behavior which allowed the quantification of cell concentration in the presence of suspended solids.An algorithm was developed for the estimation, from light scatter data, of cell concentration in the presence of solid substrate. The light scatter approach was validated by comparing cell concentrations estimated by this technique to those obtained from DNA and carbon dioxide evolution rate measurements during a series of fermentations. The model system used was Bacillus subtilis var sakainensis ATCC 21394 growing on fishmeal as the sole nitrogen source.A model was developed based on the interactions of scatter and absorbance. This model reflects the hypothesis that invariant regions are caused by changes in the absorbance of the solid substrate as a function of wavelength. © 1992 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 39 (1992), S. 898-902 
    ISSN: 0006-3592
    Keywords: diffusion coefficient ; fermentation ; Aspergillus niger ; solid state fermentor ; ion-exchange resin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple experimental diffusion controlled fermentor (DCF), coupled with the use of a mathematical model based on mass balance, is proposed to measure the variation of the gas (CO2 and O2) diffusion coefficients in solid state fermentation. The DCF was packed with an ion-exchange resin impregnated with a nutritive medium and inoculated with Aspergillus niger. The growth conditions in the DCF were very similar to those found in equipment operated with convective oxygen supply. The diffusion coefficient was shown to be very dependent on the biomass concentration within the solid state fermentor, and attained values of less than 5% of the molecular diffusion in air when the biomass in the fermentor reached 27 mg dry/g dry support.
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    Biotechnology and Bioengineering 41 (1993), S. 503-511 
    ISSN: 0006-3592
    Keywords: mathematical modeling ; fermentation ; Claviceps purpurea ; alkaloid production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An new systematic approach for describing Claviceps purpurea growth and ergot alkaloid production during batch fermentation is presented. The model is based on microbial life, as the main characteristic for microbial development during fermentation process. The aging process of the microorganism is represented by life function, defined in microbial life space. The life space is defined as a measure in which the observer follows the development of a biosystem through physiological and morphological changes of a microorganism. As a consequence of such approach the relativistic theory is recognized. To validate the model developed, a test on growth and alkaloid synthesis data from an industrial batch fermentation was performed. © 1993 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 42 (1993), S. 50-58 
    ISSN: 0006-3592
    Keywords: emulsion liquid membrane ; lactic acid ; organic acid recovery ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies on the batch extraction of lactic acid using an emulsion liquid membrane system are reported. The membrane phase consists of the tertiary amine carrier Alamine 336 and the surfactant Span 80 dissolved in n-heptane/paraffin and aqueous solutions of sodium carbonate in the internal phase. The effects of internal phase reagent, extraction temperature, and initial external phase pH on the extraction efficiency and the emulsion swelling are examined. A statistical factorial experiment on extraction from clarified lactic acid fermentation broth was carried out to obtain knowledge of the performance of the extraction system from a broth. The extraction efficiency from the fermentation broth is found to be lower as compared to aqueous solutions of pure lactic acid. The effect of pH and the presence of other ionic species on selectivity are discussed. © 1993 John Wiley & Sons, Inc.
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  • 81
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    Keywords: hybridoma ; kinetics ; curve fitting ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of partial cubic spline data interpolation for the calculation of volumetric metabolite exchange rates suggested the existence of three distinct metabolic phases during bioreactor culture of a hybridoma cell line. During phase 1, a rapid amino acid uptake rate and ammonia release rate were observed. The growth rate was low and glutamine synthetase activity fell. In phase 2, maximum growth rate and minimum glutamine assimilation and ammonium production rates were observed. Attempts to corroborate the apparent ammonia assimilation in this phase using 15NH4Cl resulted in low incorporation rates into alanine and glutamine. Maximum glutamine synthetase activity took place during this period. Maximum antibody production rate was observed during phase 3 during which peaks in glutamine assimilation, ammonia release, and glutamine synthetase activity were observed. The apparent existence of the three phases prompted us to carry out Northern blot analysis of glutamine synthetase RNA at appropriate times during the process. This revealed a pattern of appearance and dis-appearance of mRNA consistent with the three phases indicated by the fermentation parameters. © 1993 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 42 (1993), S. 538-541 
    ISSN: 0006-3592
    Keywords: ethanol ; fermentation ; levoglucosan ; lignocellulose ; pyrolysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Waterloo Fast Pyrolysis Process (WFPP) can produce an organic liquid high in levoglucosan (1, 6-anhydro-β-D-glucopyranose) content from suitably pretreated lignocellulosics. A variety of fungi and yeasts were screened for their ability to utilize and ferment this organic liquid. To enhance its fermentability, the pyrolysis tar was posttreated in three different ways: (1) an aqueous extract (lignin removed); (2) activated charcoal treated (lignin and aromatics removed); and (3) acid hydrolysate (lignin and aromatics removed with the levoglucosan hydrolyzed to glucose). Four fungal strains were examined. None grew in the aqueous extract, but all grew equally well in both the activated charcoal treated and the acid hydrolysate, suggesting that the aromatic species were inhibitory to growth. Seven yeast species were examined, two of which did not grow on any of the extracts. Five of the yeast strains grew well on both the aqueous extract as well as the activated charcoal extract. The hydrolysate was optimal in terms of biomass yield and ethanol production. Ethanol yields on the hydrolysate were comparable or better than those on glucose. Ethanol was also produced in the aqueous extract and activated charcoal-treated substrate, but yields were considerably lower than on the hydrolysate or glucose. It is apparent that a wood pyrolysate maximized for levoglucosan can serve as a fermentable substrate, although postpyrolysis clean-up appears necessary. © 1993 John Wiley & Sons, Inc.
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  • 83
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    Biotechnology and Bioengineering 42 (1993), S. 625-634 
    ISSN: 0006-3592
    Keywords: polyunsaturated fatty acid (PUFA) ; microbial oil ; gamma linolenic acid (GLA) ; production ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fatty acid production characteristics of fungi are described. These characteristics are the relationship between the oil content of the cell and the fatty acid content of the oil. For example, for polyunsaturated fatty acid (PUFA) production by Mucor hiemalis IPD 51, the oil content of the cell and the GLA content of the oil are coupled. For fungal production of some PUFA, synthesized after the rate-limiting step in the fatty acid anabolic chain, a maximum fatty acid production model was developed to link the fatty acid content of the oil and the oil content of the cell. Maximum volumetric productivity of gamma linolenic acid (GLA) by molds was found to occur at a specific GLA content of the oil. For example, for M. hiemalis IPD 51, a maximum volumetric of 4.7 mg GLA/L · h was produced at a GLA content of the oil of 8% to 10%. Similarly for Mucor circinelloides v. Tieghem IPD 155 a maximum volumetric productivity of 4.8 mg GLA/L · h was produced at a GLA content of the oil of 14% to 16%. These results imply that, when screening microorganisms for GLA or other fatty acid production, a number of medium compositions need to be evaluated to determine the tradeoff between oil content of the cell and fatty acid content of the oil. © 1993 John Wiley & Sons, Inc.
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  • 84
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    Biotechnology and Bioengineering 44 (1994), S. 1228-1234 
    ISSN: 0006-3592
    Keywords: broth recycle ; water reuse ; Apiotrichum curvatum ; fermentation ; microbial lipid ; inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation is a water-intensive process requiring treatment of large amounts of effluent broth. It is desirable to increase the ratio of product produced to the volume of effluent by minimizing the discharge of effluent from the fermentation process. A study of recycling spent fermentation process. A study of recycling spent fermentation broth for the subsequent fermentation was carried out with Apiotrichum curvatum an oleaginous yeast, as the working culture. Spent broth from a defined medium was recycled t replace as much as 75% of the water and salts for subsequent batches and this was repeated for seven sequential batches without affecting cell mass and lipid production. A 64% vlume reduction of wastewater was achieved in this manner. However, when using whey permeate as the medium, lipid production dropped after three consecutive recycle operations at 50% recycle, and after two consecutive recycle operations at 75% and 100% recycle. Accumulation of ions in the broth appeared to be responsible for the inhibition. An ion exchange step was able to eliminate the ion buildup and restore fermentation performance. © 1994 John Wiley & Sons, Inc.
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  • 85
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    Biotechnology and Bioengineering 45 (1995), S. 205-211 
    ISSN: 0006-3592
    Keywords: monoclonal antibodies ; fermentation ; fluidized bed adsorption ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To achive the coarse purification of a monoclonal antibody from whole hybridoma fermentation broth a fluidized bed cation exchange process was used. The procedure consisted of application of the crude sample and washing of the bed in a fluidized mode and elution in a fixed bed mode. A completely clarified eluate was obtained with purification factors between 4 and 8 and a concentration of the desired product (monoclonal antibody) by a factor of more than 3 was achived. Thus, a combination of the three early steps of the downstream process clarification, concentration and coarse purification was possible. Two different materials were tested: a commercially available agarose-based matrix (Stream-line-SP), and a self-derivatized material based on controlled-pore glass (Bioran). Initial experiments were performed to describe the fluidization of the glass material. Comparison with the agarose material showed several differences, the agarose matrix allowing liquid flow closer to plug flow than the glass material. Increased backmixing in the liquid phase was detected when fluidizing the glass adsorbent compared with the agarose-based matrix. Despite this fact, comparison of the two materials with respect to antibody binding and elution demonstrated a similar performance. © 1995 John Wiley & Sons, Inc.
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  • 86
    ISSN: 0006-3592
    Keywords: lignocellulose ; ethanol ; Klebisella oxytoca ; fermentation ; cellulase ; cellulose ; cellobiose ; biomass ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pretreatment of sugar cane bagasse is essential for a simultaneous saccharification and fermentation (SSF) process which uses recombinant Klebsiella oxytoca strain P2 and Genencor Spezyme CE. Strain P2 has been genetically engineered to express Zymomonas mobilis genes encoding the ethanol pathway and retains the native ability to transport and metabolize cellobiose (minimizing the need for extracellular cellobiase). In SSF studies with this organism, both the rate of ethanol production and ethanol yield were limited by saccharification at 10 and 20 filter papaer units (FPU) g-1 acid-treated bagasse. Dilute slurries of biomass were converted to ethanol more efficiently (over 72% of theoretical yield) in simple batch fermentations than slurries containing high solids albeit with the production of lower levels of ethanol. With high solids (i.e., 160 g acid-treated bagasse L-1), a combination of 20 FPU cellulase g-1 bagasse, preincubation under saccharification conditions, and additional grinding (to reduce particle size) were required to produce ca. 40 g ethanol L-1. Alternatively, almost 40 g ethanol L-1 was produced with 10 FPU cellulase g-1 bagasse by incorporating a second saccharification step (no further enzyme addition) followed by a second inoculation and short fermentation. In this way, a theoretical ethanol yield of over 70% was achieved with the production of 20 g ethanol 800 FPU-1 of commercial cellulase. © 1994 John Wiley & Sons, Inc.
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  • 87
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    Biotechnology and Bioengineering 45 (1995), S. 245-250 
    ISSN: 0006-3592
    Keywords: Escherichia coli enterotoxin ; fed batch ; high cell density ; fermentation ; purification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: High cell density fermentation studies were performed to produce the B subunit of Escherichia coli heat-labile enterotoxin (LTB) from a Vibrio cholerae culture that carries a recombinant plasmid with an ampicillin resistance gene, tac promoter, and the gene encoding LTB. Upon induction with isopropyl-β-D-thiogalactopyranoside (IPTG) the culture secreted the protein into the extracellular milieu. Fed-batch fermentation with stepwise addition of a total of 5 mM of IPTG during the active growth phase of the organism resulted in the production of 400 mg/L of LTB in 9 h and a cell optical density (OD) of 24. The LTB was purified to homogeneity with 70% recovery from the fermentation broth and was found to be chemically and biologically identical to the native protein by N-terminal amino acid sequencing and receptor binding assay. © 1995 John Wiley & Sons, Inc.
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  • 88
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    Biotechnology and Bioengineering 47 (1995), S. 444-450 
    ISSN: 0006-3592
    Keywords: acetone-butanol fermentation ; fermentation ; cell recycle ; fed-batch ; clostridium acetobutylicum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel acetone-butanol production process was developed which integrates a repeated fed-batch fermentation with continuous product removal and cell recycle. The inhibitory product concentrations of the fermentation by Clostridium acetobutylicum were reduced by the simultaneous extraction process using polyvinylpyridine (PVP) as an adsorbent. Because of the reduced inhibition effect, a higher specific cell growth rate and thus a higher product formation rate was achieved. The cell recycle using membrane separation increased the total cell mass density and, therefore, enhanced the reactor productivity. The repeated fed-batchoperation overcame the drawbacks typically associated with a batch operation such as down times, long lag period, and the limitation on the maximum initial substrate concentration allowed due to the substrate inhibition. Unlike a continuous operation, the repeated fed-batch operation could beoperated for a long time at a relatively higher substrate concentration without sacrificing the substrate loss in the effluent. As a result, the integrated process reached 47.2 g/L in the equivalent solvent concentration (including acetone, butanol, and ethanol) and 1.69 g/L · h in the fermentor productivity, on average, over a 239.5-h period. Compared with a controlled traditional batch acetone-butanol fermentation, the equivalent solvent concentration and the tormentor productivity were increased by 140% and 320%, respectively. © 1995 John Wiley & Sons Inc.
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  • 89
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    Biotechnology and Bioengineering 49 (1996), S. 1-14 
    ISSN: 0006-3592
    Keywords: polyhydroxyalkanoate ; poly(3-hydroxybutyrate) ; biodegradable plastic ; biopolymer ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates (HAs) synthesized by numerous bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. More than 80 HAs have been detected as constituents of PHAs, which allows these thermoplastic materials to have various mechanical properties resembling hard crystalline polymer or elastic rubber depending on the incorporated monomer units. Even though PHAs have been recognized as good candidates for biodegradable plastics, their high price compared with conventional plastics has limited their use in a wide range of applications. A number of bacteria including Alcaligenes eutrophus, Alcaligenes latus, Azotobacter vinelandii, methylotrophs, pseudomonads, and recombinant Escherichia coli have been employed for the production of PHAs, and the productivity of greater than 2 g PHA/L/h has been achieved. Recent advances in understanding metabolism, molecular biology, and genetics of the PHA-synthesizing bacteria and cloning of more than 20 different PHA biosynthesis genes allowed construction of various recombinant strains that were able to synthesize polyesters having different monomer units and/or to accumulate much more polymers. Also, genetically engineered plants harboring the bacterial PHA biosynthesis genes are being developed for the economical production of PHAs. Improvements in fermentation/separation technology and the development of bacterial strains or plants that more efficiently synthesize PHAs will bring the costs down to make PHAs competitive with the conventional plastics. © 1996 John Wiley & Sons, Inc.
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  • 90
    ISSN: 0006-3592
    Keywords: one-line monitoring ; fermentation ; cell culture ; monoclonal antibodies ; real-time immunoassays ; BioCad/RPM ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On-line, “real-time” monitoring of product concentration is important for mammalian cell culture fermentation. The continuous measurement of monoclonal antibodies allows for instantaneous determination of cell productivity and effective manipulation of the fermentor operating conditions for optimal production. This article will present the evaluation and application of a BioCad/RPM system (Per Septive Biosystems) for rapid analysis of lgG concentration for hybridoma cell cultivation. Several commercial crossflow filtration devices are tested for low protein retention and fouling properties. A protein G column is used successfully for analyzing about 400 samples of lgG1, without significant loss in separation efficiency. The Immuno Detection system is integrated into a computer-controlled 15-L fermentor. This fermentor could be operated in batch and perfusion modes with cell densities up to 20 million cells/mL. A continuous cell-free sample stream obtained by a hollow fiber filter system is introduced to the BioCad/RPM for analysis. The speed of this system allows for real-time monitoring even at high densities with fast dynamics. A murine hybridoma cell (A10G10) is cultivated in batch and continuous reactors and antibody concentration is measured continuously with complete sterility. The results are compared to offline measurements with good agreement. © 1995 John Wiley & Sons, Inc.
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  • 91
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    Biotechnology and Bioengineering 51 (1996), S. 131-140 
    ISSN: 0006-3592
    Keywords: mixing power ; convection ; fermentation ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The phenomena of mixing and mass transfer of substrates to microorganisms greatly affect the biochemical reactions which take place in fermentation processes. The effect that agitation power has on the observable reaction kinetics involved in beer fermentation has been studied in different types of bioreactors, from laboratory to industrial scale. With this aim in mind, an effectiveness factor, η, is introduced which is defined as the relation between the existing rate of reaction, whichever bioreactor is considered, and the reaction rate in the well-mixed, and therefore presumably homogeneous, bioreactor with no diffusional limits. The limitation to homogeneously supplying nutrient material to the cells produces a decrease in this effectiveness factor, which has been correlated to the energy dissipation rate with a similar slope to that which appears in an existing correlation in the literature between this energy and the mass transfer coefficient. Additionally, a dimensionless reaction-convection number, NRC, which is a function of the power input per unit volume, is proposed, which has been appropriately employed in correlating the effectiveness factor for the types of processes in which convection may be the key resistance factor. © 1996 John Wiley & Sons, Inc.
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  • 92
    ISSN: 0006-3592
    Keywords: glycolysis ; Zymomonas mobilis ; flux control ; fermentation ; ethanol ; glucose 6-phosphate dehydrogenase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glycolytic genes in Zymomonas mobilis are highly expressed and constitute half of the cytoplasmic protein. The first four genes (glf, zwf, edd, glk) in this pathway form an operon encoding a glucose permease, glucose 6-phosphate dehydrogenase (G6-P dehydrogenase), 6-phosphogluconate dehydratase, and glucokinase, respectively. Each gene was overexpressed from a tac promoter to investigate the control of glycolysis during the early stages of batch fermentation when flux (qCO2) is highest. Almost half of flux control appears to reside with G6-P dehydrogenase (CJG6-P dehydrogenase = 0.4). Although Z. mobilis exhibits one of the highest rates of glycolysis known, recombinants with elevated G6-P dehydrogenase had a 10% to 13% higher glycolytic flux than the native organism. A small increase in flux was also observed for recombinants expressing glf. Results obtained did not allow a critical evaluation of glucokinase and this enzyme may also represent an important control point. 6-Phosphogluconate dehydratase appears to be saturating at native levels. With constructs containing the full operon, growth rate and flux were both reduced, complicating interpretations. However, results obtained were also consistent with G6-P dehydrogenase as a primary site of control. Flux was 17% higher in operon constructs which exhibited a 17% increase in G6-P dehydrogenase specific activity, relative to the average of other operon constructs which contain a frameshift mutation in zwf. It is unlikely that all flux control residues solely in G6-P dehydrogenase (calculated CJG6-P dehydrogenase = 1.0) although these results further support the importance of this enzyme. As reported in previous studies, changes in flux were not accompanied by changes in growth rate providing further evidence that ATP production does not limit biosynthesis in rich complex medium. © 1996 John Wiley & Sons, Inc.
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  • 93
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    Biotechnology and Bioengineering 52 (1996), S. 713-717 
    ISSN: 0006-3592
    Keywords: abiotic proton balance ; fermentation ; linear relations ; net conversion rates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Linear relations among net conversion rates of primary metabolites in fermentation processes can be determined by using the macroscopic or pathway balancing methods. It is shown that the process observability can be improved by incorporating both the abiotic proton balance and the pH control reagent addition rate measurement into the balancing methods. © 1996 John Wiley & Sons, Inc.
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  • 94
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    Biotechnology and Bioengineering 54 (1997), S. 17-25 
    ISSN: 0006-3592
    Keywords: hybridoma cell culture ; fermentation ; MAb heterogeneity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A stable murine hybridoma cell line, secreting IgG1 antibodies (7H3) against the soluble type I receptor for Tumor Necrosis Factor (sTNF-R1), was cultivated in two different bioreactor systems, a hollow fiber and a stirred tank fermentor, in order to evaluate the effect of culture conditions on antibody structural and functional heterogeneity. Conventional serum-supplemented and serum-free media were chosen for fermentation in stirred tank bioreactor, whereas only serum-supplemented media were used for hollow fiber cultivation. Extent of glycosylation, determined by lectin binding assays, and charge heterogeneity of murine monoclonal antibodies displayed relevant variations according to the fermentation system used. After complete sugars removal by N-glycosidase F treatment, charge heterogeneity were still observed suggesting the occurrence of additional modifications at the protein level. In vitro culture in serum-supplemented media carried out with the hollow fibre system led to higher productivity but greater antibody charge heterogeneity and differences in lectin-binding profile than cultivation in the stirred tank bioreactor.Results cumulatively indicated that hybridoma cultivation methods, but also cultivation time, influence antibody heterogeneity, both in the protein and sugar moieties. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 17-25, 1997.
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  • 95
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    Biotechnology and Bioengineering 55 (1997), S. 715-726 
    ISSN: 0006-3592
    Keywords: fungal morphology ; pellets ; hyphae ; hair of pellets ; agitation intensity ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Both parallel fermentations with Aspergillus awamori (CBS 115.52) and a literature study on several fungi have been carried out to determine a relation between fungal morphology and agitation intensity. The studied parameters include hyphal length, pellet size, surface structure or so-called hairy length of pellets, and dry mass per-wet-pellet volume at different specific energy dissipation rates. The literature data from different strains, different fermenters, and different cultivation conditions can be summarized to say that the main mean hyphal length is proportional to the specific energy dissipation rate according to a power function with an exponent of -0.25 ± 0.08. Fermentations with identical inocula showed that pellet size was also a function of the specific energy dissipation rate and proportional to the specific energy dissipation rate to an exponent of -0.16 ± 0.03. Based on the experimental observations, we propose the following mechanism of pellet damage during submerged cultivation in stirred fermenters. Interaction between mechanical forces and pellets results in the hyphal chip-off from the pellet outer zone instead of the breakup of pellets. By this mechanism, the extension of the hyphae or hair from pellets is restricted so that the size of pellets is related to the specific energy dissipation rate. Hyphae chipped off from pellets contribute free filamentous mycelia and reseed their growth. So the fraction of filamentous mycelial mass in the total biomass is related to the specific energy dissipation rate as well.To describe the surface morphology of pellets, the hyphal length in the outer zone of pellets or the so-called hairy length was measured in this study. A theoretical relation of the hairy length with the specific energy dissipation rate was derived. This relation matched the measured data well. It was found that the porosity of pellets showed an inverse relationship with the specific energy dissipation rate and that the dry biomass per-wet-pellet volume increased with the specific energy dissipation rates. This means that the tensile strength of pellets increased with the increase of specific energy dissipation rate. The assumption of a constant tensile strength, which is often used in literature, is then not valid for the derivation of the relation between pellet size and specific energy dissipation rate. The fraction of free filamentous mycelia in the total biomass appeared to be a function of the specific energy dissipation in stirred bioreactors. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 715-726, 1997.
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  • 96
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    Biotechnology and Bioengineering 40 (1992), S. 1282-1285 
    ISSN: 0006-3592
    Keywords: Candida shehatae ; ethanol ; D-xylose ; viability ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ethanol was added at concentrations of 25 and 50 g/L to active cultures of Canida shehatae under oxygen-limited (fermentative) conditions. Added ethanol completely inhibited grwoth and fermentation of D-xylose by C. shehatae. Cultures with added ethanol rapidly declined in cell viability as measured by plate counts and methylene blue staining. The rate of decline in cell viability was dependent on the amount of added ethanol. Over the course of the fermentation, cell viability, as measured by plate counts, was significantly lower in all experiments (with or without ethanol addition) compared with the viability measurements by methylene blue staining. Thus, data from the plate counts provided a more sensitive measure of the toxic effects of added ethanol and long-term anaerobiosis on C. shehatae growth/fermentation. Mean cell volume and total cell volume declined in fermentations with added ethanol. © 1992 John Wiley & Sons, Inc.
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  • 97
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    Biotechnology and Bioengineering 41 (1993), S. 830-832 
    ISSN: 0006-3592
    Keywords: ionic equilibrium ; pH computation ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An algorithm developed for pH computation has been tested to calculate the theoretical pH changes in a culture medium during the course of a fermentation. A divergence between the computed pH value and the value measured with the electrode allows us to highlight the presence of undetected ionic products. The calculation with the algorithm by means of a computer requires only the knowledge of the ionic properties of the substrates and detected products and existing thermodynamic constants. © 1993 Wiley & Sons, Inc.
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  • 98
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    Biotechnology and Bioengineering 43 (1994), S. 314-320 
    ISSN: 0006-3592
    Keywords: Spongiococcum exetricicum ; fed-batch fermentation ; fermentation ; microalgae fermentation ; feedback control ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimization of cellular productivity of an industrial microalgae fermentation was investigated. The fermentation was carried out at Coors Biotech Products Company, Fort Collins, Colorado. A mathematical model was developed based on the data collected from pilot plant test runs at different operating conditions. Pontryagin's maximum principle was used for determining the optimal feed policy. A feedback control algorithm was also studied for maximizing the cellular productivity. During continuous operation, the optimum dilution rate was determined by an adaptive optimization scheme based on the steepest descent technique and a recursive least squares estimation of model parameters. A direct search algorithm was also applied to determine the optimum feed rate. Comparison of the theoretical results of the different optimization schemes revealed that the direct search algorithm was preferable because of its simplicity. The experimental results of real time application of the feedback algorithm agreed fairly well with those of the theoretical analyses. © 1994 John Wiley & Sons, Inc.
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  • 99
    ISSN: 0006-3592
    Keywords: acetate production ; E. coli ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An integrated metabolic model for the production of acetate by growing Escherichia coli on glucose under aerobic conditions is presented. The model is based on parameters which are easily determined by experiments. Forming the basis for this integrated metabolic model are the 12 principal precursor metabolites for biosynthetic pathways, the Embden-Meyerhof-Parnas pathway, the pentose phosphate cycle, the tricarboxylic acid cycle and the anapleurotic reactions, the Crabtree effect, the Pasteur effect, and the details of bacterial respiration. The result can be used to explain phenomena often observed in industrial fermentations, i.e., increased acetate production which follows from high glucose uptake rate, a low oxygen concentration, a high specific growth rate, or a combination of these conditions. © 1993 John Wiley & Sons, Inc.
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  • 100
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    Biotechnology and Bioengineering 42 (1993), S. 1175-1180 
    ISSN: 0006-3592
    Keywords: self-cycling fermentation ; secondary metabolite ; biosurfactant ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Self-cycling fermentations (SCFs) were conducted in a stirred tank apparatus using Bacillus subtilis and Acinetobacter calcoaceticus. The systems were very stable and the experiments lasted through many cycles. The variation of parameters such as biomass and doubling time from cycle to cycle was small. The stirred tank reactor (STR) allowed a much better control of the working volume in the fermentor from cycle to cycle, compared to the cyclone column, and it was not necessary to make periodic corrections.The production of surfactin from B. subtilis was achieved without extending the cycle time. The harvested broth at the end of each cycle was allowed to remain in a secondary vessel, at ambient temperature, before being collected. It is exhaustion of the limiting nutrient which causes an increase in dissolved oxygen (DO). At this point, the computer, which constantly monitors the DO, triggered the harvesting sequence to end the cycle. Thus, the mature culture in the secondary vessel experienced appropriate conditions for the production of the secondary metabolite. Meanwhile, the next batch of cells was being grown in the primary reactor.The response of a gas analyzer on the effluent paralleled that of the DO measurements in the fermentor. These data for oxygen and carbon dioxide exhibited less noise than the DO readings. Either would be a more reliable parameter for feedback control of the SCF because the problem of fouling of the DO probe after extended runs of many cycles would be eliminated. © 1993 John Wiley & Sons, Inc.
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