Bacterial community structure in pig manure composted with a deodorizing strain combination

Abstract:

[Background] Aerobic composting is a common resource utilization method to treat agricultural solid waste, while odorous gases (NH₃ and H₂S) generated during the composting process pose a threat to the health of humans and animals. Microbial deodorization has low costs and good effects, while single strains have poor environmental adaptability and limited effects. [Objective] To develop a combination of efficient deodorizing strains and optimize microbial deodorization conditions to address the foul odor in composting. [Methods] The effects of the deodorizing strain combination on the changes of bacterial community structure during composting were studied by screening of deodorizing microbial strains and temperature-controlled simulated composting. Furthermore, the relevant functional genes were analyzed and annotated. [Results] The maximum release of NH₃ and H₂S from the compost supplemented with the deodorizing strain combination E was only about 40% of that from the compost treated with the commercial microbial agent X. The species classification results show that the phyla with relatively high abundance during composting include Proteobacteria, Actinomycetota, Firmicutes and Bacteroidota. Group E showed higher relative abundance of Proteobacteria and Actinomycetota than groups X and CK. The dominant genera included Pseudomonas, Corynebacterium, and Pseudogracilibacillus, among which Corynebacterium kept being dominant in group E. The annotation results from the KEGG database indicated that the addition of the deodorizing strain combination E promoted the amino acid metabolism in the microbial community during composting. Similarly, functional gene annotation results revealed higher abundance of ammonia assimilation-related genes (gs, gdh, asn, and gln) and the sulfur-containing amino acid synthesis-related gene (cysC), suggesting that the combination E reduced NH₃ and H₂S emissions by facilitating the conversion of nitrogen and sulfur into amino acids and other organic compounds. [Conclusion] The deodorizing strain combination E can effectively inhibit the release of NH₃ and H₂S in the manure composting process, providing microbial resources for the treatment of waste gases generated in the manure resource utilization process.

Key words:deodorizing strain combination;aerobic composting;NH₃;H₂S;bacterial community