Genetic instability of industrial strains of Penicillium chrysogenum.
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.
Institut für Mikrobiologie und experimentelle Therapie (ZIMET) Jena, Federal Republic of Germany.
W
W
Künkel
D
D
Berger
S
S
Risch
B
B
Wittmann-Bresinsky
D007218:Industrial Microbiology; D010406:Penicillins / Q000096:biosynthesis*; D010408:Penicillium chrysogenum / Q000235:genetics*; D011003:Ploidies; D012641:Selection, Genetic
D010406:Penicillins