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  • Title: Genetic instability of industrial strains of Penicillium chrysogenum.
    Author: Künkel W, Berger D, Risch S, Wittmann-Bresinsky B.
    Journal: Appl Microbiol Biotechnol; 1992 Jan; 36(4):499-502. PubMed ID: 1368203.
    Abstract:
    It has shown that several characteristics of high-producing industrial strains of Penicillium chrysogenum tend to segregate in the course of cultivation (slant-to-slant transfer). Segregation includes a decrease in the yield of penicillin, mean conidial size, mean size of the nuclei, and an increase in the proportion of morphologically wild-type colonies. These lower-producing segregants also have a higher sensitivity against ultraviolet radiation and, as shown by cytofluorometric methods, a lower DNA content in the conidia, a decrease in phosphate uptake and in the activity of extracellular alkaline phosphatases compared to high-producing strains. Obviously, during mutagenesis/selection programmes ploidy mutants have been selected, which entails an increase in the number of genes coding enzymes responsible for penicillin biosynthesis. In the absence of selection pressure these high-producing strains segregate to lower-producing strains by chromosome losses in the course of slant-to-slant transfers.
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