GLUCOSE-OXIDASE OVERPRODUCING MUTANTS OF PENICILLIUM VARIABILE (P16)

Conidia of Penicillium variabile P16 were subjected to mutagenesis and selection for glucose oxidase production on media containing o-dianisidine. Studies of the relationship between dose of UV irradiation and conidial survival and frequency of mutation showed that the best frequency of positive mutation (17%) was obtained in correspondence to a conidial survival of 52%. Out of 54 overproducing mutants tested in shaken flasks, M-80.10 showed the highest level of glucose oxidase activity (127% higher than the wild-type). M-80.10 mutant, transferred every 15 days to fresh medium and tested monthly for 8 months, appeared stable. The time course of growth and enzyme production by the mutant M-80.10 showed an increase of the glucose oxidase activity in the culture medium up to 19 U ml(-1) after 96 h of fermentation.