Research On Characteristics And The Change Of Microbial Community Structure In Continuous Anaerobic Fermentation From Different C/N-contained Materials

The pig manure,needle mushroom fungus bag,rice straw and sugarcane leaves as the different C/N material were applied in the continuous anaerobic fermentation in order to resolve the characteristics of anaerobic fermentation and structural change analysis of bacterial flora.The characteristics of anaerobic fermentation were obtained from the batch anaerobic fermentation and continuous anaerobic fermentation.The structural changes of bacterial flora in the continuous anaerobic fermentation were analyzed by denaturing gradient gel electrophoresis(DGGE)technology.The main contents are as follow:(1)The methane potential test was done by the Automatic Methane Potential Test System II(AMPTS II)that is explored by Sweden BioProcess company.The results indicated that the methane production potential of pig manure,needle mushroom fungus bag,rice straw and sugarcane leaves was 387.4.2±8.6、210.2±12.0、269.0±8.8 and 152.4±16.7 mL/gVS,respectively.The methane production potential of material was related to the material types,material structure and nutritional composition and other factors.The rate curve of daily methane yield was close.The peak of methane yield was achieved in a short time,and then the rate of daily methane yield was decreased with the time increasing gradually.However,the peak time of the methane yield was different.The peak time of sugarcane leaves,rice straw pig manure and needle mushroom fungus bag was second,fourth,fifth and fifth day,respectively.The peak value of sugarcane leaves,rice straw pig manure and needle mushroom fungus bag was 76.3,130.8,279.5 and 137.8 mL,respectively.The four kinds of materials could be decomposed in a relatively short period of time,and 90% methane production was prepared.(2)The four kinds of materials were made in the continuous anaerobic fermentation experiment which the hydraulic retention time was 30 days,and the OLR was 1.11,1.67,2.22 and 2.78 gVS/(L.d),respectively.It was shown that the daily methane production increased when the OLR was increased.The daily methane yield of pig manure was the highest,and quickly response to the increases of OLR.However,the diversity index of bacteria and archaea decreased with the increase of the OLR,and the methane production declined.The C/N of the needle mushroom fungus bag was about 24:1 which was the most suitable for microbial growth.Its(3)physical and chemical properties were relatively stable.The diversity index of bacteria and archaea increased with the increases of the OLR,and the rate of methane yield of unit material was about 140 mL/(gVS)and relatively stable.The C in the rice straw and sugarcane leaves was rich,and the diversity index of microbial community increased when their OLR was increased firstly.However,the bacteria and archaea were suppressed so that the diversity index of microbial community decreased and the methane production declined under the condition that the OLR was2.78 gVS/(L.d).The structural changes of bacterial flora and dominant bacteria in the continuous anaerobic fermentation were affected by the different C/N of materials,which was analyzed by denaturing gradient gel electrophoresis technology.There were seven dominant bacteria in the four kinds of materials made in the continuous anaerobic fermentation experiment,such as Bacteroides,Carboxylicivirga,Treponema,Clostridium,and so on.Dethiosulfovibrio salsuginis belongs to the dominant bacteria from pig manure which grows in the moderate alkaline condition,and produces acid through lipolysis.Acetivibrio cellulolyticus and Proteiniphilum acetatigenes belong to the dominant bacteria from needle mushroom fungus bag and sugarcane leaves pig manure.There were acetic acid nutrition type,hydrogen nutrition type and methyl nutrition type archaea,which were identified for dominant archaea and could produce methane.There were seven dominant bacteria in the four kinds of materials made in the continuous anaerobic fermentation experiment,such as Methanobacterium,Methanothiermoccous and Methanomassiliicoccus luminyensis,and so on.There were five dominant bacteria in needle mushroom fungus bag,rice straw and sugarcane leaves made in the continuous anaerobic fermentation experiment,such as Methanococcus maripaludis,Methanobrevibacter smithii,Methanoculleus hydrogenitrophicus,Methanospirillum hungatei and Methanosaeta concilii.Methanolobus zinderi belongs to the dominant bacteria from pig manure.