MUTANTS OF CAROTENE PRODUCTION IN BLAKESLEA-TRISPORA

The filamentous fungus Blakeslea trispora, an industrial carotene sour ce, contains beta-carotene and precursors of its synthesis - phytoene, phytofluene, lycopene, and gamma-carotene. Strain improvement through mutagenesis is difficult because all life stages are multinucleate. M utants have been obtained following exposure of wild-type spores to N- methyl-N'-nitro-N-nitroso-guanidine. Changes in the colour of the myce lia reflect variations in the accumulation of various precursors and t he final product. Quantitative analysis of the mutants leads to the co nclusion that the biosynthetic pathway is similar to that of the relat ed fungus Phycomyces blakesleeanus, but the regulation is completely d ifferent. In particular, interruption of the pathway does not lead to overacummulation of precursors.