Strain improvement of Rhizopus oryzae for production of l(+)-lactic acid and glucoamylase

Thirty‐eight l(+)‐lactic acid‐overproducing mutants were isolated by mutagenizing a parent strain of Rhizopus oryzae NRRL 395 with u.v. and/or N‐methyl‐N'‐nitro‐N‐nitrosoguanidine. Three mutants, 1N1, 3N4 and 3N6, were found to yield significantly more l(+)‐lactic acid in a rice medium than the parent strain. Of the mutants examined, only mutant 3N4 produced more glucoamylase than the parent strain.