Selective Isolation of Fusarium graminearum Mutants Derepressed for Production of β-Glucosidase

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Abstract
A strain of Fusarium graminearum produced extracellular β-glucosidase (β-d-glucoside glucohydrolase [EC 3.2.1.21]) subject to carbon catabolite repression. Derepressed mutants were selectively isolated by the use of 2-deoxyglucose, a nonmetabolizable catabolic repressor. On each plate of cellobiose and 2-deoxy-glucose inoculated with 106 spores and irradiated with UV light, a few colonies emerged. Comparative growth experiments with one of the derepressed mutants and the parent strain showed that the mutant produced β-glucosidase in the presence of glucose. Furthermore, the same mutant produced more β-glucosidase than did the wild-type strain on cellobiose alone.