Use of a series of chemostat cultures to isolate ‘improved’ variants of the Quorne myco-protein fungus, A3/5 Free

Abstract

Variants (designated A23-S and A24-S) of the Quorne myco-protein fungus, A3/5 were isolated from a series of glucose-limited cultures grown at a dilution rate of 0.18 hfor a combined total of 109 d. These variants had unchanged mycelial morphologies but, when grown in mixed culture with the parental strain (A3/5) in glucose-limited chemostat culture at 0.18 h, A23-S and A24-S had selection coefficients of 0.013 and 0.017 h, respectively, and supplanted A3/5. When a monoculture of A23-S was grown in a glucose-limited culture at a dilution rate of 0.18 h, the appearance of highly branched (so-called colonial) mutants was delayed compared with their appearance in chemostat cultures of the parental strain. Furthermore, when a monoculture of A24-S was grown in glucose-limited culture at 0.18 h, the appearance of colonial mutants was delayed even further. Thus, it is possible to isolate advantageous (relative to A3/5) variants of A3/5 which have unchanged mycelial morphologies, but in which the appearance of colonial mutants is delayed.

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1994-11-01
2024-03-28
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