The impact ofBacillus coagulansX3 on available nitrogen content, bacterial community composition, and nitrogen functional gene levels when composting cattle manure

Abstract

This study was designed to probe available nitrogen levels, bacterial community composition, and the levels of nitrogen functional genes present when composting cattle manure with or without the addition ofBacillus coagulansX3. Bacterial supplementation was associated with the prolongation of the thermophilic stage and improved maturity of the resultant compost. At the maturity stage, samples to whichB. coagulansX3 had been added exhibited significant increases in ammonium nitrogen, nitrate nitrogen, and total nitrogen levels. The dominant bacterial phyla observed in these composting samples were Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteriota, and Chloroflexi.B. coagulansX3 addition resulted in significant increases in relative Firmicutes abundance during the thermophilic and cooling stages, while also increasingamoAandnosZgene abundance and reducingnirSgene levels over the course of composting. Together, these data suggest thatB.coagulansX3 supplementation provides an effective means of enhancing nitrogen content in the context of cattle manure composting through the regulation of nitrification and denitrification activity.