Metagenomics Sequencing and Binning Reveal the Diversity, Assembly and Synergistic Variation of Microbial Sulphur Cycling Genes under Corpse Decay

The decay of animal corpses may release various nutrients into the surrounding environment and participate in the biogeochemical cycle. However, few studies have involved the sulphur cycle in animal corpse decay. Here, we conducted an indoor control experiment at five different temperature gradients (23, 26, 29, 32 and 35 °C) to explore the change of sulphur cycling microbes and genes under corpse decay by metagenomic sequencing, metagenomic binning, and 16S rRNA sequencing. Our results showed that total sulphur content decreased by 41.82% due to decomposition. The dominant phyla of the S-cycle microbes were Proteobacteria, followed by Bacteroidetes and Acidobacteria. Corpse decay decreased the pathways involved in assimilatory sulphate reduction, sulfur oxidizing (Sox) system, organic sulphur transformation, and sulphur oxidation pathway, but increased the links between inorganic and organic sulphur transformation. The alpha diversity of sulphur cycling genes decreased with increasing temperature and the deterministic process was dominant in most of temperature gradients. The diversity of microbial community was the main driving factors of sulphur cycling genes, followed by corpse decay and temperature. We obtained 257 high-quality metagenome assembled genomes (MAGs) containing sulphur cycling genes, and the results of metagenome-assembled genomes provide evidence for the covariation of sulphur cycling genes, such as sir, cysD, cysH, and ssuC, which shared the function of assimilatory sulphate reduction. Our research reveals the pathways of microbial sulphur cycling and contributes to the understanding of the elemental cycle associated with animal corpse decay.