Formation Mechanism And Application Of Lignocellulose Degradation Microbial Community

Nowdays overuse of fossil energy leads to environmental problems such as global warming,deterioration of ecosystem,widespread haze.With the double press of energy safe and environmental pollution,biomass resources get more and more attention.Improper conducts of straw resources like burning bring about air pollution and resources waste.Microbial community has the ability of effectively degrading lignocelluloses material.The further study of microbial community would theoretically support the utilization of lignocelluloses material like straw resources.The aim of this study is to further prove the formation mechanism of microbial community,reveal the mechanism of "Reverse out" and "Balance the acid and alkali" in long-time restrictive cultures.The following results are gotten:1.Multiple microbial communities were screening by long-time restrictive culture.The microbial seed source was compost from different fermentation stage,and the substrate was rice straw.Microbial communities A2 and A3 were screened from a source of rotten period composting,and microbial communities B1 and B3 were screened from a source of high temperature period composting.Though A2,A3 and B1,B3 had different community structure,all of them had good ability in straw decomposition.There was no significant difference in degrading capability among them.2.The change of microbes in restrictive culture process met the "Reverse out" rule,while some different change also had a chance and occurred occasionally.After restrictive culture,microbial structure of screened microbial communities and compost bacteria flora were obviously different.A lot of microbes who had low correlation with cellulose decomposing were eliminated.The community structure changed all through the screen process,and lead to a unstable state,which increased the occurrence chance of out rule change.Under the same culture condition and from the same source of microbe seed,microbial community A1's straw degradation rate was significantly lower than parallel microbial communities A2 and A3,and three days pH was much higher than A2 and A3's.3."Balancing the acid and alkali" of community that pH declined slowly and community that pH return back slowly.Before mixed,auxiliary represented by producing alkali bacteria Alcaligenes got a high quantitative proportion(67.06%)in microbial community A1,and the quantitative proportion of potential decompose lignocelluloses microbes was very low.Those lead to a low straw weight loss and a slow pH decline.While in microbial community A3 and B3,quantitative proportion of auxiliary bacteria were low,potential decompose lignocelluloses microbes were higher compared with Al.Straw weight loss rate of A3 and B3were high,and a fast declined pH.However pH returned back slowly in A3 and B3.After mixed,potential decomposing bacteria and auxiliary bacteria were adjusted to a appropriate proportion,the new communities maintained high straw weight loss rate and pH change of them comply with the principle of stable microbial community." "Balancing the acid and alkali" is beneficial to secure a stable microbial community.4.High-throughput sequencing technology has been used to study microbial community structure of ADC6,MC1,WSD5,WDC2 and XDC2.Those microbial communities were screened under the condition of high temperature or medium temperature,and with substrate of rice straw or wheat straw.Archaea were found in those five microbial communities;Community composition might be influenced by culture temperature and substrate.Microbial diversity of WSD5 and XDC2 in medium temperature microbial community was higher than that of high temperature microbial community ADC6,MC1 and WDC2.5.Explored the application of microbial community MC1 in the biogas anaerobic fermentation,the following results are gotten:1)Microbial community MC1 had strong decomposition capability and community structure maintained stable.MC1 was used to pretreat rotted silage maize straw which carried many microbes prior to biogas production.After 5 d pretreatment,MC1 enhanced biogas yields by 74.7%compared with the untreated group.The proportions of five key strains in MC1 were almost the same as in the unsterilized and sterilized groups,MC1 was resistant to microbial contamination.2)Methanogens could grow in microbial community MCI.Based on characteristics of MC1 the simple operation,low cost biological additive for bioaugmentation were explored.After added biological additive to the high organic load,high volatile organic acid accumulation anaerobic digestion system,the biogas yields were increased by 11.75%to 24.78%.It indicated that the bioaugmentation was helpful for anaerobic digestion system recovery.