SELECTION AND CULTIVATION OF CELLULOSE-DEGRADING AND LIGNIN-DEGRADING FUNGI

Wood-degrading fungi isolated from different sources, and cultures from collections of the Institute of Microbiology and Institute of Botany, Uzbekistan Academy of Sciences,, were screened. Among the 34 selected cultures possessing cellulose-degrading capability, 15 were capable of oxidizing tannin and gallic acid, which is characteristic of ligninolytic cultures. The following active cultures of basidiomycetes were selected: Panus tigrinus (Bull. ex. Fr.) Sing. UzBI-013, Pleurotus ostreatus (Jacg. ex. Fr.) Kumm. UzBI-H105, Fomes fomentarius (L. ex. Fr.) Kickx. Fr. UzBI-155, and Inonotus hispidus (Pers.) UzBI-T8. They actively utilized hemp-mallow shaft lignin (HMSL) as the sole source of carbon in the medium. It was established that cellulolytic, xylanolytic, and ligninolytic enzymes were produced during growth of the cultures on ligninocellulose wastes (depleted bagasse of cotton seed ground oilcake, rice hull, and hemp-mallow shaft). Along with cellobiase, endoglucanase, and xylanase activity, P. ostreatus and P. tigrinus fungi were capable of secreting the enzymes peroxidase and laccase, unlike F. fomentarius and I. hispidus, which did not secrete laccase. The chemical composition of ligninocellulose wastes was studied before and after cultivation of the fungi. During 30-day growth and development of the fungi, 23-78% of cellulose was utilized, 21-80.4% of hemicellulose, and 21-58% of lignin. Degradation of biopolymers was highest during 10 days of fungal cultivation. It was shown that the production of those enzymes responsible for biopolymer degradation depended on the composition of the ligninocellulose components of the medium.