Isolation Of Effective Cellulytic Anaerobic Bacteria, Construction And Application Of Mix Culture

Cellulosic materials are the main substrates for the stage of hydrolysis during the anaerobic digestion of agricultural waste. Because of their insolubility and heterogeneity, they are extremely difficult to be degraded. It is the limited step of the whole fermentation to use them. The study of pure culture and mix culture which are capable of degrading cellulose has important applied value for the anaerobic decomposition of biomass. This research is also a preparation for the microorganism agent of biogas fermentation.The results concluded: (1)Ten mesophilic cellulytic anaerobic bacteria were isolated by Hungate anaerobic technique, which ascribed to four species in Clostridium, from the diverse environments. Strain CSZM-6 isolated from wetwood of trees was ascribed to Clostridium papyrosolvens primarily based on the physiological and biochemical characteristics and phylogenetic analysis. Its specific taxonomic status should be determined by further trials.(2)Microbial communities h-11 and CBC which were constructed by natural selection were capable of degrading cellulose to methane with high efficiency. Irrespective of the initial pH of the medium with inoculum, the pH values reached approximately neutrality or meta-alkalescence in the end of fermentation. The degradation ability was tolerant to heating at 100°C for 30 minutes. The range of growth pH and temperature were wide. Under the optimal conditions, the paper filter degradation ratios of h-11 and CBC consortias were 78.87% and 73.23% within 5 days at 45°C respectively. The waste materials riched in cellulose can be degraded without pretreatment and /or sterilization. (3)The addition of h-11 mix culture led to 3.72% increase in biogas production with 70 days at about 30°C. The biogas production increased by 114.1% with 50 days before fermentation ending at about 20°C, the effect distinct, extending the whole fermentation period. The conversion rate of substrates and biogas quality were improved. In field trial, after the addition of the microorganism agent , which contained mix culture capable of using cellulose, biogas production improved markedly at low temperature(15℃～-3℃～13℃)with enough raw materials in methane-generating pit for farm household.