Isolation,identification,and community structure analysis of thermophilic bacteria during composting
The addition of thermotolerant bacterial agents is a common technique to accelerate the composting process and improve compost quality.Combined with the culture omics research method with 48 culture conditions,including 6 culture media,2 oxygen environmental conditions(aerobic & anaerobic)and 4 high temperature scenarios(50,60,70,and 80 ℃),196 thermotolerant strains were isolated and purified from the thermophilic stage of composting.A total of 35 species belonging to 14 genera from 4 phyla of thermotolerant bacteria were identified.Among them,the phylum Firmicutes(98％),the genus Bacillus(51.5％)and Bacillus licheniformis(28.6％)were predominant at the phylum,genus,and species levels,respectively.Additionally,some thermotolerant genera such as Caldibacillus and Thermus were also identified.Among the isolated strains,27 exhibited thermophilic characteristics and showed enhanced degradation capabilities for at least one of the macromolecules(starch,cellulose,protein,and fatty acids)under high-temperature conditions,with 6 thermophilic strains simultaneously demonstrating strong degradation capabilities for all four macromolecular organic compounds.Furthermore,a comparative analysis of the thermotolerant bacterial community structures in high-temperature compost samples from different sources was conducted through 16S rRNA amplicon sequencing.The results revealed that the phyla Firmicutes,Actinobacteria,and Bacteroidetes were dominant,while the genera Bacillus,Savagea,Caldibacillus,Limnochorda,and Proteocatella were the predominant thermotolerant genera.The study highlighted the need for further screening and exploration of thermotolerant/thermophilic bacterial resources in composting,with a requirement for the establishment of more diversified cultivation conditions.Moreover,functional predictions of the thermotolerant bacterial community using PICRUSt2 indicated that sugar metabolism,amino acid metabolism,and cofactor and vitamin-related metabolism were the predominant metabolic pathways during the high-temperature composting phase.
compostingthermotolerant bacteriaisolation and purificationthermotolerant bacterial communityfunction prediction
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