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Appl. Environ. Microbiol., Sep 1997, 3657-3661, Vol 63, No. 9
BJ Mehta, LM Salgado, ER Bejarano and E Cerda-Olmedo
The accumulation of (beta)-carotene by the zygomycete Phycomyces
blakesleeanus is increased by mutations in the carS gene. The treatment of
spores of carS mutants with N-methyl-N(prm1)-nitro-N-nitrosoguanidine led
to the isolation, at very low frequencies, of mutants that produced higher
levels of (beta)-carotene. Strain S556 produced about 9 mg of
(beta)-carotene per g of dry mass when it was grown on minimal agar.
Crosses involving strain S556 separated the original carS mutation from a
new, unlinked mutation, carF. The carF segregants produced approximately as
much carotene as did carS mutants, but they were unique in their ability to
produce zygospores on mating and in their response to agents that increase
carotenogenesis in the wild type. The carotene contents of carF segregants
and carF carS double mutants were increased by sexual interaction and by
dimethyl phthalate but were not increased by light or retinol. Mixed
opposite-sex cultures of carF carS mutants contained up to 33 mg of
(beta)-carotene per g of dry mass. Another strain, S444, produced more
(beta)-carotene than did S556 but was marred by slow growth, defective
morphology, and bizarre genetic behavior. In all the strains tested, the
carotene concentration was minimal during the early growth phase and became
higher and constant for several days in older mycelia.
Copyright © 1997, American Society for Microbiology
New Mutants of Phycomyces blakesleeanus for (beta)-Carotene Production
Departamento de Genetica, Universidad de Sevilla, Seville, Spain
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