Wild-type strain

Transform into wild-type strain parental strand is not replicated... 

Wild type Strain of microorganism isolated from nature. The usual or native form of a gene or organism. 

The small overproduction of amino adds by wild type strains in culture media is the result of regulatory mechanisms in the biosynthetic pathway. These regulatory mechanisms are feedback inhibition and repression. 

Metabolic pathways containing dioxygenases in wild-type strains are usually related to detoxification processes upon conversion of aromatic xenobiotics to phenols and catechols, which are more readily excreted. Within such pathways, the intermediate chiral cis-diol is rearomatized by a dihydrodiol-dehydrogenase. While this mild route to catechols is also exploited synthetically [221], the chirality is lost. In the context of asymmetric synthesis, such further biotransformations have to be prevented, which was initially realized by using mutant strains deficient in enzymes responsible for the rearomatization. Today, several dioxygenases with complementary substrate profiles are available, as outlined in Table 9.6. Considering the delicate architecture of these enzyme complexes, recombinant whole-cell-mediated biotransformations are the only option for such conversions. E. coli is preferably used as host and fermentation protocols have been optimized [222,223]. 

The gene for the dehydratase was expressed in E. coli under lac promoter, and an expression plasmid pOxD 90F was constructed. The transformant was cultivated under optimal condition at 30° C when much of the enzyme was expressed in a soluble form with more than thousand and several hundred times than the wild-type strain per culture (up to more than 50% of the total soluble protein of the... 

The PGI and PGII produced from strains transformed with the promoter gene fusion are in all respects tested identical to those enzymes obtained from the wild type strain when grown on pectic substances. For both PGI and PGII the pH optimum is 4.1-4.2 in 50 mM Na-acetate buffer, 30 °C. All further kinetic analyses were performed under these conditions. 

Sp245 Wild type strain, isolated from surface sterilized weat roots (Brazil) Baldani et a/., 1986... 

LMG10653 (KBC 1) wild type strain, isolated from roots and rhizosphere of rice (Iraq) Khammas e/o/., 1989... 

A. nidulans with selected phages of classes A, B, C, D and E resulted in increased polygalacturonase activity in comparison with the wild type strain. The culture media of pga transformants were further analysed by Western blotting with polyclonal antibodies raised against PGI and in all samples examined cross-reactive bands with molecular masses similar to that found for PGI or PGII were detected. 

The growth of pel mutants was compared with that of the wild-type strain.The growth rate of mutant and parental strains was similar during the first 48 h following inoculation. After this period of time, the growth of mutants was slighdy reduced. 

Lee at al. [17] recently reported that the cellular PHB accumulated in the wild-type strain of Rb. sphaeroides KCTG 12085 up to 21.9 pg/mg dry weight of cells, while the mutant did not accumulate PHB during photo-incubation. 

When acetate was used as a carbon source, the initial pH 6.8-7.0 was increased to 9.2-9.4 by the wild-type strain but 7.4-7 6 by the mutant strain. The increase in pH by the wild-type strain might be due to the accumulation of PHB in cells. Khatipov et a/. [11] also found that in nitrogen-deprived cells, the initial medium pH 7.5 increased to 10 and at the same time, PHB accumulation increased twice as compared to cells grown from an initial pH 6.8. Hydrogen production in this case decreased more than eightfold. 

Wild type strain of Rb.sphaeroides KD 131 grew well in the Sistrom s broth containing... 

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