SUMMARY: A method of heterokaryon isolation with Penicillium chrysogenum is described where mycelium from mixed growth of two auxotrophs was fragmented and dispersed on a medium which only supported heterokaryon growth. This method overcomes the difficulties of producing heterokaryons in this organism which are ascribed to its slow growth rate. When heterokaryons grew they sometimes gave colonies which sectored from the centre into regions which, although still heterokaryotic, had widely different conidial ratios of each component strain. The nucleus was the major component in the inheritance of penicillin production but a minor effect was exerted through the cytoplasm. The yellow pigment, chrysogenin, produced by some strains of P. chrysogenum, was inherited as a nuclear-controlled character which was not a recessive trait.
ClutterbuckP. W.,
LovellR.,
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MacdonaldK. D.,
HutchinsonJ. M.,
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