| Summary: | Nitrogen loss is an unavoidable problem during organic waste composting, while exogenous microbial inoculation is a promising strategy for reducing nitrogen loss and improving compost quality. 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 of <i>Bacillus coagulans</i> X3. Bacterial supplementation was associated with the prolongation of the thermophilic stage and improved maturity of the resultant compost. At the maturity stage, samples to which <i>B. coagulans</i> X3 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. <i>B. coagulans</i> X3 addition resulted in significant increases in relative Firmicutes abundance during the thermophilic and cooling stages while also increasing <i>amoA</i> and <i>nosZ</i> gene abundance and reducing <i>nirS</i> gene levels over the course of composting. Together, these data suggest that <i>B</i>. <i>coagulans</i> X3 supplementation provides an effective means of enhancing nitrogen content in the context of cattle manure composting through the regulation of nitrification and denitrification activity.
|
|---|