Isolation Of Effective Banana Stalk Cellulose-Degrading Microorganism And Construction Of Composite Microbial System

In the paper, isolation of effective banana stalk cellulose-degrading microorganism from nature, identification and optimization enzyme production conditions were carried out. Meanwhile, combining culture of isolated strain and purchase of effective cellulose-decomposing strain, proper strains combination was obtained through banana stalk degradation test. The results could be summerized as follows:First,99 cellulose-degrading strains were isolated from banana gardens by using mineral salt media(MSM) added banana stalk as solo carbon source. The degradation ratio of strains was measured by CMC enzyme activity (CMC) and filter paper enzyme activity (FPA). Eight of the strains showed higher enzymes activity, which contained 3 bacteria,4actinomycete and 1 fungi. The FPA of one fungus(11F4) was equivalent to that of Trichoderma Koningii, which was recognized strain with high cellulase activity. Basing on 18srDNA, the sequence of the strain 11F4 has 99.4% homology with the 18S rDNA of plectosphaerella cucumerina。Second, the effects of incubation time, carbon source, nitrogen source, temperature, initial PH and incubation concentration on enzyme production conditions were determined. The highest enzyme production activity showed under the conditions of banana stalk and wheat bran(mass ratio of 9:1) as carbon source,30℃, PH6, incubation concentration 10% and urea as nitrogen source when the strain was cultured in 4d. Under the optimal enzyme production condition。Third, the effects of strains combination culture (isolated stain and strain from nature; nature strain and purchase of effective cellulose-decomposing strain) on biodegradation capacity of coarse fiber of banana stalk were studied through measuring the content of coarse fiber after solid fermentation. The results indicated that:Comparing with pure culture,6 combinations could enhance biodegradation rate of lignocelluloses of banana stalk. The combination of 11F4 and Penicillium janthinellum showed the highest biodegradation rate, whose biodegradation rate of coarse fibre was 29.71%, higher than that of 11F4 and Penicillium janthinellum pure culture 5.46 and 9.32 percentage point respectively. And the content of coarse fibre of samples came down to 22.17% under the optimal combination.