Methane-producingcomposite Strains Anaerobic Digestion And Microbialcommunity Structure Analysis

Anaerobic digestiontechniqueis an effective treatment method of agriculture organic wastes. Recently, anaerobic digestion is widely applied to convert biomass waste into methane worldwide.Howere the anaerobic digestionsystem of high-efficiency and stable operation are immature,andlacked of deep research on microorganisms.To solve above problems, theresearchonacclimatizationand optimizationof the methane-producingcomposite strains is crucial.According to the characteristics of the composite strains in two-phase anaerobic digestionsystem toanalysis gas efficiency and the response to temperature changed.Theanalysis of the community structurethrough high-throughput sequencingprovide microbiological guidance for two-stage anaerobic digestion system.A group of methane-producingcomposite strains wasobtainedthrough subculture.Through the single factor and orthogonal experiment to optimize the culture conditions, ultimately got the optimal culture conditions for:TS concentration was12%, the C/N was27:1, PH 7.0.The resultof methanogenic characteristics ofmethane-producing composite strainsintwo-stage anaerobic digestionsystem showed that gas production of acidification-phasewas notaffected bycomposite strains, howere theacidification rate was improved.The organic waste decompositionrate was affected by temperature.The concentration of s COD and VFA gradually decreased as the temperature decreased.Composite strains can effectively improve the biogas production of methanogenic-phase, the periodic cumulative gas production increased by 51.2% and the gasproduction stabilizationtime shortened 10 d compared with control group.Methanogenic-phase gradient cooling fermentation research showed that biogas production rate, the TS productivity and gas volume biogas productionwere declined as thetemperaturedecreased.The gas production disturbance was more drastic when the temperature decressed. Thebiogas production was 3900 m L/dat 30°C stable operation period, 25°C, 23°C and 20°Cof biogas production was reduced by 33.6%, 47.2% and 33.6%respectively.The results on Miseq sequencing analysis tomicrobial community structurein two-stage anaerobicdigestion systemshowed that the community diversity of acidification-phase at 35°Cand methanogenic-phaseat 30°Cwere higher compared with other temperature period.The dominant bacterial communities of acidification-phase at35°C,30°C and 25°Cwere Clostridia and Bacteroidia,20°Cwere Gammaproteobacteria and Bacilli. In methanogenic-phase gradient coolingfermentation,the abundance of bacterial groups was higherunder the 30°C and 25°C,lacked of dominant bacterial communities.Bacill and Gammaproteobacteria weredominant bacterial communities at 23°C,Bacteroidia and Clostridiaweredominant bacterial communities at 20°C.Methanogenswere dominanted by Euryarchaeotaandunculturedarchaea, unclassified archaea accounted for a large proportion.Theresponse ofthe community structure to temperature changed showed that the acidification-phase of communitydiversity is higher under the mesotherm.Unclassified Bacteroidales, Unclassified Sybergistaceaeand Clostridium sp.were the functional microbial.The dominant bacteria ofmethanogenic-phase under the mesotherm were Unclassified Chloroflexi,Unclassified Anerolineaceae and Proteiniclasticum sp..The dominantmethanogens was Uncultured euryarchaeote and Uncultured archaeon.The methanogenic-phase of community structure was affected by low temperature fluctuationis more remarkable.When the temperature droped to 20°C, community structure and species abundance werechanged, then methanogenic-phasec of gas efficiency and operational stability decreased.