Regulation of Endo-1,4-beta-glucanase Production in Sporotrichum pulverulentum

Abstract

Regulation of endo-1,4-β-glucanases in the white-rot fungus Sporotrichum pulverulentum has been investigated using a new, sensitive method. The method is based upon the viscosity-lowering effect of endo-1,4-β-glucanases on solutions of CM-cellulose. The effect of inducers and repressors can be determined whether the enzymes are localized on the cell wall surfaces or are released into the surrounding solution. The results show that cellobiose causes induction at concentrations as low as 1 mg/l and that glucose concentrations as low as 50 mg/l cause repression of the enzyme formation. Mixtures of inducer and repressor produce a delayed induction compared with solutions of inducer only. Corresponding studies of the mould Trichoderma viride show that cellobiose is not an efficient inducer. Sophorose, however, causes induction of endo-1,4-β-glucanases at 1 mg/l. In mixtures of sophorose and glucose a delayed induction time is also obtained with this fungus. The comparison between the regulation of endo-1,4-β-glucanases in the two fungi shows several other important differences. Thus the solution with CM-cellulose alone induces enzyme formation in S. pulverulentum but not in T. viride. In our experiments no endo-1,4-β-glucanases were actively excreted into the solution by T. viride. the enzymes were bound to the cell wall. S. pulverulentum, however, released the enzymes into the solution although they first appeared bound to the cell wall. These differences imply that the two fungi in their natural environments assure their nutrition in different ways.