corpse decomposition and water volume

Corpse decomposition has caused lots of pollution to the environment threatening public health. At present, the distribution of antibiotic resistance genes (ARGs) has expanded and attracted the attention of numerous scholars. However, whether microbial communities and ARGs are affected by the large volume in the carcass decomposition remains unknown compared with previous researches in the small volume. We investigated the effect of the large volume on microbial communities and ARGs during cadaver decomposition based on 16S rRNA high-throughput sequencing and high-throughput quantitative PCR. Our results showed the large volume almost eliminated the effects of corpse decomposition on pH, total organic carbon (TOC), and total nitrogen (TN). ARGs were predominated by those resisting tetracycline and efflux pump mechanisms. Under 62.5 fold enlargement of the water volume, the relative abundance of some ARGs in carcass decomposition decreased about 217 fold on average, while there was also a mean 5,267 fold increase of some ARGs. The absolute abundance of ARGs resisting vancomycin and the relative abundance of ARGs resisting tetracycline, vancomycin, and sulfonamide were affected by the large volume. The alpha diversity of the microbial community decreased in the large volume, while it increased in the small volume during cadaver decomposition. The beta diversity of the microbial community was also affected by volume significantly. The abundance of opportunistic pathogens (Bacteroides) was influenced by both the corpse decomposition and the volume. Further, Bacteroides and Comamonas may be potential hosts of ARGs in carcass decomposition and expand the potential for the spread of ARGs to the environment and humans. This research highlights that the "dilution effect" can contribute to eliminating this adverse effect during corpse decomposition to a certain extent. It may provide references for environmental governance and public health.