Inoculation regulates nitrogen transformation and microbial community
during livestock manure composting
The effects of three Bacillus strains and one Saccharomyces cerevisiae
strain on nitrogen transformation and microbial communities in pig and
chicken manure compost were investigated. The findings revealed that
employing compound microbial inoculants raised compost temperature,
expedited moisture reduction, enhanced cellulase activity, and
stimulated the accumulation of NH4+-N, NO3–N, and total nitrogen (TN),
resulting in a 9% increase in TN content. The abundance of Firmicutes
at the maturation phase decreased by 3.95%, Actinobacteria and
Bacteroidetes increased by 1.64% and 1.85%, respectively. Inoculation
resulted in an augmentation of amoA, nxrA, and nifH gene copy numbers,
while concurrently reducing the abundance of nirK, nosZ, and nirS genes.
Furthermore, it led to an increase in functional enzyme levels,
specifically nif and amo, along with a corresponding decrease in nor.
Clostridium, Phascolarctobacterium, Eubacterium, and Faecalibacterium
from class Clostridium, which exists a significant correlation with nifH
and nxrA genes, suggesting their likely pivotal role in nitrogen
retention and fixation. Inoculation helped remove pathogenic bacteria
and ARGs like fluoroquinolones, nucleoside and nitroimidazole. This
study provide effective theoretical support for nitrogen retention and
fixation mechanism and improving the quality of compost.