Identification and genomic analysis of a thermophilic bacterial strain that reduces ammonia loss from composting.

ABSTRACT

Ammonia loss is the most severe during the high-temperature stage (>50°C) of aerobic composting. Regulating ammonia volatilization during this period via thermophilic microbes can significantly improve the nitrogen content of compost and reduce air pollution due to ammonia loss. In this study, an ammonia-assimilating bacterial strain named LL-8 was screened out as having the strongest ammonia nitrogen conversion rate (32.7%) at high temperatures (50°C); it is able to significantly reduce 42.9% ammonia volatile loss in chicken manure composting when applied at a high-temperature stage. Phylogenetic analysis revealed that LL-8 was highly similar (>98%) with Priestia aryabhattai B8W22T and identified as Priestia aryabhatta. Genomic analyses indicated that the complete genome of LL-8 comprised 5,060,316 base pairs with a GC content of 32.7% and encoded 5,346 genes. Genes, such as gudB, rocG, glnA, gltA, and gltB, that enable bacteria to assimilate ammonium nitrogen were annotated in the LL-8 genome based on the comparison to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The results implied that the application of thermophilic ammonia-assimilating strain P. aryabhatta LL-8 would be a promising solution to reduce ammonia loss and mitigate air pollution of aerobic composting.IMPORTANCEAerobic composting is one of the essential ways to recycle organic waste, but its ammonia volatilization is severe and results in significant nitrogen loss, especially during the high-temperature period, which is also harmful to the environment. The application of thermophilic bacteria that can use ammonia as a nitrogen source at high temperatures is helpful to reduce the ammonia volatilization loss of composting. In this study, we screened and identified a bacteria strain called LL-8 with high temperature (50°C) resistance and strong ammonia-assimilating ability. It also revealed significant effects on decreasing ammonia volatile loss in composting. The whole-genome analysis revealed that LL-8 could utilize ammonium nitrogen by assimilation to decrease ammonia volatilization. Our work provides a theoretical basis for the application of this functional bacteria in aerobic composting to control nitrogen loss from ammonia volatilization.