Carotene-superproducing strains of Phycomyces.

Production of beta-carotene by wild-type Phycomyces blakesleeanus can be stimulated by light, chemicals, regulatory mutations, and sexual interaction between mycelia of opposite sex. Through genetic manipulations, we have isolated strains which have simultaneously and constitutively incorporated several of these stimulatory effects. In the dark and in a simple medium, some of the strains produce up to 25 mg of beta-carotene per g (dry weight), or about 500 times the wild-type production under the same conditions. High lycopene-producing strains have also been isolated by using carR mutants, which are blocked in the conversion of lycopene to beta-carotene. These strains should be useful in both industrial production of these pigments and basic research related to carotenogenesis.