L-Cysteine Synthase Enhanced Sulfide Biotransformation in Subtropical Marine Mangrove Sediments as Revealed by Metagenomics Analysis

Abstract

High sulfides concentrations can be poisonous to environment because of anthropogenic waste production or natural occurrences. How to elucidate the biological transformation mechanisms of sulfide pollutants in the subtropical marine mangrove ecosystem has gained increased interest. Thus, in the present study, the sulfide biotransformation in subtropical mangroves ecosystem was accurately evaluated using metagenomic sequencing and quantitative polymerase chain reaction analysis. Most abundant genes were related to the organic sulfur transformation. Furthermore, an ecological model of sulfide conversion was constructed. Total phosphorus was the dominant environmental factor that drove the sulfur cycle and microbial communities. We compared mangrove and non-mangrove soils and found that the former enhanced metabolism that was related to sulfate reduction when compared to the latter. Total organic carbon, total organic nitrogen, iron, and available sulfur were the key environmental factors that effectively influenced the dissimilatory sulfate reduction. The taxonomic assignment of dissimilatory sulfate-reducing genes revealed that Desulfobacterales and Chromatiales were mainly responsible for sulfate reduction. Chromatiales were most sensitive to environmental factors. The high abundance of cysE and cysK could contribute to the coping of the microbial community with the toxic sulfide produced by Desulfobacterales. Collectively, these findings provided a theoretical basis for the mechanism of the sulfur cycle in subtropical mangrove ecosystems.

Living in mangroves: a syntrophic scenario unveiling a resourceful microbiome

“…2 d). In such tidal microhabitats, the sulfate deposition would favor the increase in abundance of SRB, which grow by sulfate reduction to sulfide, coupled with oxidation of hydrogen or organic compounds [ 34 , 70 ] (Fig. 2 e).…”

“…The electrochemical conditions may be balanced by volatile fatty acids (VFA) production and oxidation (Fig. 2 f) and sulfide biotransformation strategies [ 34 ] (Fig. 2 g).…”

“…3 a; Table 2 ). The presence of DSR genes in these MAGs is expected since members of Desulfobacterales [ 27 , 34 , 72 , 81 ], and Thermodesulfovibrionales [ 82 – 84 ] orders are known as SRB. The enrichment of genes related to sulfate reduction were previously described in Brazilian mangroves [ 4 , 7 , 8 , 30 , 31 , 72 ].…”

“…The enrichment of genes related to sulfate reduction were previously described in Brazilian mangroves [ 4 , 7 , 8 , 30 , 31 , 72 ]. SRB activity is strongly dependent on several environmental factors, with genes working in both reductive and oxidative directions [ 34 , 78 ]. Although the presence of DSR genes per se does not confirm SRB activity, flux was predicted in DE and TH88 (Table 3 ).…”

“…The advent of environmental DNA (eDNA) methods such as metagenomics has been a driving force of biodiversity discovery, allowing the investigation of unknown uncultured organisms and providing access to the genetic content of whole communities from any ecosystem [ 7 , 32 ]. Most mangrove studies using eDNA have explored, for example, the impacts of anthropogenic contamination [ 27 , 29 – 31 , 33 ], detailed investigations on methane, nitrogen and sulfur cycling genes/pathways [ 4 , 11 , 34 ], enzymes with potential use in biotechnological processes [ 15 , 16 , 22 , 23 , 25 , 26 , 30 , 35 ], community responses to global warming and sea level rising [ 5 , 12 , 21 , 36 ], and microbial diversity of mangroves from distinct biomes to micro-habitats [ 12 , 37 ].…”