Increased Cellulase Activity of EO22 in Binary Associations with Streptomycetes

The search for new methods for activating and controlling the enzymatic activity of cellulose destructor organisms through joint cultivation is relevant. is a basidiomycete from the group of white rot fungi, known for its biotechnological versatility. It has not yet found effective application in the field of bioconversion of agricultural waste, in particular, straw of cereals. An assessment of the possibility of creating based on a strain EO22 artificial bacterial and fungal associations for the development of an effective strategy for the utilization of straw, a by-product of crop production. The effects of co-cultivation of EO22 with cellulolytically active bacteria of the genus Streptomyces were studied. The dynamics of cellulase activity was determined during the cultivation of EO22 fungus in monoculture and in binary cultures with strains Mb4-2, T1-3, N27-25, “” H13-3. Binary crops were grown in a liquid mineral medium with straw as the only carbon source. The enzyme activity was measured in a culture liquid supernatant at 50°C and pH 5 according to the initial rate of formation of reducing sugars, the concentration of which was determined spectrophotometrically at 540 nm with a reagent based on 3,5-dinitrosalicylic acid. As a unit of activity, such an amount of enzyme was taken, when exposed to the substrate in an enzymatic reaction, 1 micromole of reducing sugars in terms of glucose equivalent is formed in 1 hour. The cellulase activity of EO22 joint cultures with each of the bacterial strains reached a maximum 3-6 days earlier than in the monoculture of the fungus (maximum reached on the 7th day) under the same conditions. When the fungus was co-cultured with the Mb4-2 strain, there was no significant increase in cellulase activity (122 ± 13.1 units/ml) compared with the monoculture of the fungus (114.4 ± 37.1 units/ml). The maxima of cellulase activity of binary associations with strains T1-3, N27-25 and H13-3 exceeded the maximum of the EO22 monoculture by 2.3, 1.6 and 1.3 times, respectively. The degree of decomposition of straw, determined by weight loss, increased by 10.3, 2.3 and 22.4%, respectively, compared with the monoculture of the fungus. There was no statistically significant correlation between a decrease in straw weight and cellulase activity under experimental conditions. The results obtained indicate the prospects of creating artificial bacterial and fungal associations for the effective destruction of straw and other cellulose--containing waste from crop production.