Carcass degradation and denitrifying community

Corpse degradation may release amounts of hazardous materials (e.g., cadaverine, putrescine and ammonia) into surrounding areas, which deteriorate environments and result in nitrogen contamination. Denitrifying bacteriacan reduce nitrate or nitrite to nitrogen gas, thus alleviating nitrogen pollution and purifying aquatic environments. However, the reaction of nirS-encoding denitrifiers on carcass degradation is less studied. Therefore, we used high-throughput sequencing technologies and water physiochemical analysis to explore the succession of nirS denitrifying communities in tap water and Yellow river water during three stages of animal cadaver decay (submerged fresh, advanced floating decay and sunken remains) as well as the corresponding control groups. NH4+-N and NO3-N concentration in the corpse groups are higher than that in control groups. The dominant phylum for nirS denitrifying communities was Proteobacteria. Abundant denitrifying genera Paracoccus, Alicycliphilus and Diaphorobacter were detected, and these genera have been reported to participate in the degradation of organic pollutants. Particularly, nirS-type community structures were remarkably influenced by corpse decay and become similar with succession. Water total dissolved solids (TDS), salinity, conductivity (CON) and phosphate, but not water type, were the main impacting factors driving the community structures. Notably, null model analysis showed that deterministic processes rather than stochastic processes dominated the denitrifying community assembly, and the relative importance of deterministic processes in most of the corpse groups was higher compared with the control groups, indicating that environmental filtering regulates the denitrifying communities. Our results provide new insight into environmental purification for hazardous materials produced by corpse degradation, thereby providing valuable advice to environmental administration.