Analysis Of Microbial Community Structure And Metabolite Characteristics In Aerobic Composting Of Pig Manure

In this study,pig manure and corn stalks were used as composting materials,and microbial sequencing,metabolomics and separation and culture techniques were used to analyze the succession of microbial community and the characteristics of microbial metabolites in the process of pig manure composting.The test content and results were shown as follows:(1)A laboratory-scale aerobic fermentation reactor was used for pig manure compost fermentation.Composting was divided into three stages: mesophilic phase,thermophilic phase,and cooling phase.During the composting process,the p H increased first and then decreased.Compared with the initial composting,the content of NH4+-N increased significantly on the fourth day of composting(P<0.05).Microbial sequencing results showed that the dominant bacteria at the genus level were Pseudomonas(8.90%),Lactobacillus(3.99%),Bacteroides(3.39%)and Flavobacterium(3.25%).Lactobacillus had the greatest abundance in mesophilic phase;In the high temperature phase,the abundance and diversity of microbial communities decreased,and the abundance of Bacteroides first increased and then decreased;Compared with the Day–0 of composting,the abundance of Pseudomonas and Flavobacterium increased by 14.12% and 4.08%,respectively during cooling period(P<0.05).Gene function prediction results showed that the abundance of genes encoding corresponding metabolic function modules was higher than the abundance of genes encoding cellular processes and genetic information processing functions.(2)Metabolomics analysis was carried out on the samples of 3 phases of composting.The SA_SD group,SA_SF group and SD_SF group were screened out 1005,1095 and 1007 differental metabolites,respectively.These metabolites were classified into lipids,polyketides,organic heterocyclic compounds,benzoates,nucleotides and their analogs.Among them,fatty acyl substances accounted for 27.36%,25.57% and 24.13% of the three comparison groups,respectively.The three metabolic pathways of linoleic acid metabolism,primary bile acid biosynthesis,and peroxisome proliferator activated receptor(PPARs)signal transduction were extremely enriched in the compost(P<0.01).In terms of the correlation of metabolites,Pseudomonas,Flavobacterium,and Proteobacterium had different correlations with Prevotella for the same metabolites in compost(P<0.05).(3)Through isolation and culture technology,a strain that could reduce ammonia production during the high temperature period of composting was screened out,and the strain was identified as B.paraconglomeratum of the genus Brachybacterium.At 4% of the inoculation dose,the ammonia suppression rate could reach 42%.