Products from fermentation mutant

Figure 8 Isolation of mutants deficient in the 4-OH cyclohexanecarboxylic acid metabolic pathway. Thin-layer chromatography radioautogram of ethyl acetate extractable products from doramectin fermentation dosed with [14C]-labeled cyclohexanecarboxylic acid. TLC was done on Kieselgel 60 F254 20 X 20 cm plates (E. Merck) and developed using benzene, ethyl acetate, and formic acid (25 25 2). Lanes A, uninoculated medium B and C, culture 109-123 D and E, mutant 324-52.

The most commonly used strain in cellulase production is the mutant from T. reesei, whose optimal temperature for growth is in the range 30-32 °C, and the optimal temperature for cellulase accumulation is 26-28 °C [2, 26]. During solid-state fermentation, a heat of metabolism will be released because of the... 

Phenylalanine production from a plasmid harbouring auxotrophic mutant of E. caii has been studied in batch cultures. Phenylalanine is produced in the stationary phase due to the release of feedback inhibition after depletion of tyrosine. The fermentation can be sununarised as ... 

The discovery of milbemycins was first reported by researchers from Sankyo in 1974 [36, 37]. The original producing strain SANK 60576 was designated Streptomyces hygroscopicus subsp. aureolacrimosus [38]. The fermentation products from this Actinomycete and its mutants are many. Thirteen milbemycins were isolated from the original strain, they were named ol to aio and to [39]. Later, the ai component was named milbemycin A3, the as component milbemycin A4. More derivatives were isolated from mutant strains [40, 41], among them milbemycin D (Fig. 29.6.3). 

Methionine is overproduced by auxotrophic and analogue-resistant mutants. E. coli K-12 mutant resistant to methionine analogues (norleucine, ethionine, and methyl methionine) produced 2mg/ml of methionine. A multianalogue-resistant mutant of Corynebacterium lilium resistant to ethionine, norleucine, and methionine sulfoxide yielded 2.3 g/L methionine in a 5L fermenter.Methionine production from different analogue-resistant yeasts are also reported in the late 1970s and 1980s. ° Mondal et al. have reported methionine production from methionine-analogue-resistant mutants of Brevibacterium heali. 

PHB synthesis from a mutant strain A. vinelandii using glucose in a batch reactor was optimized by Dhanasekar et al. The initial medium pH significantly affects the productivity. Incubation temperature does not have a significant role in PHB production. Substrate concentration significantly affects the productivity as well as the PHB yield. It was observed that maximum productivity was observed with short fermentation period and lag phase were also minimized. 

Research on growth and ethanol production by Z. mobilis is also in progress at the United States National Renewable Energy Laboratory or NREL (Himmel et al. 1997) and elsewhere (Zakpaa et al. 1997 Joachimsthal et al. 1998 McLellan et al. 1999 Silveira et al. 2001). The topics of these studies range from the selection of a mutant capable of ethanol production from glucose in the presence of 20 g/1 of sodium acetate (Joachimsthal et al. 1998) to the mechanism that causes an oscillatory behavior in the continuous fermentation of Z. mobilis... 

Ion-exchange resins are used for isolation of lysine from fermentation broths. The eluted lysine then is crystallized from water. The most common commercial form of lysine used in animal feed is 98 percent lysine monohydrochloride. It is equivalent to 78.4 percent of the amino acid lysine, which can be metabolized by animals to body proteins. The supplementation level is about 0.5 percent lysine in feed. When the Brevibacterium mutant is used to produce lysine, the entire fermentation broth may be evaporated and dried, and the dried product used as animal feed supplement. 

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