Impacts of Desulfobacterales and Chromatiales on sulfate reduction in the subtropical mangrove ecosystem as revealed by SMDB analysis

Sulfate reduction is an important process in the sulfur cycle. However, the relationship between this process and the genotype of microorganisms involved in subtropical mangrove ecosystems is poorly understood. A dedicated and efficient gene integration database of sulfur metabolism has not been established yet. In this study, a sulfur metabolism gene integrative database (SMDB) had been constructed successfully. The database achieved high coverage, fast retrieval, and low false positives. Then the sulfate reduction by microorganisms in subtropical mangroves ecosystem had been evaluated quickly and accurately with SMDB database. Due to the environmental factors, dissimilatory sulfite reductase was significantly high in mangrove samples. Sulfide, Fe, and available sulfur were found to be the key environmental factors that influence the dissimilatory sulfate reduction, in which sulfur compounds could be utilized as potential energy sources for microorganism. Taxonomic assignment of dissimilatory sulfate-reduction genes revealed that Desulfobacterales and Chromatiales are completely responsible for this process. Sulfite reductase can help the community cope with the toxic sulfite produced by these Bacteria order. Collectively, these findings demonstrated that Desulfobacterales and Chromatiales play essential roles in dissimilatory sulfate reduction.