Beyond the tip of the iceberg; a new view of the diversity of sulfite- and sulfate-reducing microorganisms

Abstract

Sulfite-reducing and sulfate-reducing microorganisms (SRM) play important roles in anoxic environments, linking the sulfur and carbon cycles. With climate warming, the distribution of anoxic habitats conductive to dissimilatory SRM is expanding. Consequently, we hypothesize that novel SRM are likely to emerge from the rare biosphere triggered by environmental changes. Using the dsrB gene as a molecular marker of sulfite-reducers and sulfate-reducers, we analyzed the diversity, community composition, and abundance of SRM in 200 samples representing 14 different ecosystems, including marine and freshwater environments, oil reservoirs, and engineered infrastructure. Up to 167,397 species-level OTUs affiliated with 47 different families were identified. Up to 96% of these can be considered as "rare biosphere SRM". One third of the dsrB genes identified belonged to uncharacterized lineages. The dsrB sequences exhibited a strong pattern of selection in different ecosystems. These results expand our knowledge of the biodiversity and distribution of SRM, with implications for carbon and sulfur cycling in anoxic ecosystems.

Sulfur intermediates as new biogeochemical hubs in an aquatic model microbial ecosystem

“…In the anoxic saline layer, the dissimilatory sulfate reduction pathway (Sat, Qmo, AprAB and DsrAB genes) occurred in the Deltaproteobacteria bins as expected [7], but was also found in genomic bins a liated with Chlorolexi, Planctomycetes, Calditrichaeota and Parcubacteria (Ca. Nealsonbacteria, Ca.…”

“…Although sulfate reduction and sul de oxidation have received most attention, our knowledge of the identity of microorganisms and metabolic pathways involved in these processes is limited and novel lineages of microorganisms mediating steps in the sulfur cycle remain to be discovered [6,7].…”

“…Due to the abundance of sulfur compounds in sea water, much of our knowledge on sulfur cycle comes from marine sediments, which constitute a major biotope for sulfur cycling microorganisms [3]. However, the distribution of sulfur cycling microorganisms is not limited to marine environments, and sulfur cycling microorganisms also have important ecological roles in sulfate-poor environments such as wetlands and lakes [7,15].…”

Distinct assembly mechanisms underlie similar biogeographical patterns of rare and abundant bacteria in Tibetan Plateau grassland soils

“…The bacteria in low abundance represent the majority of Earth's biodiversity [1], and these rare bacteria contain an enormous pool of genetic novelty [2]. Accumulating evidence has confirmed the crucial ecological functions of rare bacteria in terrestrial and aquatic ecosystems.…”

Draft Genome Sequence of Desulfofundulus thermobenzoicus subsp. thermosyntrophicus DSM 14055, a Moderately Thermophilic Sulfate Reducer

“…The taxonomic and ecological distribution and genetic diversity of dissimilatory sulfate-reducing microorganisms remain topics of significant interest, with major relevance for understanding biogeochemical cycles (10,11), including the regulation of methanogenesis in sedimentary environments (11)(12)(13). The genome of D. thermobenzoicus is therefore valuable for expanding our understanding of sulfate reducers capable of syntrophic growth with methanogens, as well as for improving the genomic representation of sulfate-reducing Firmicutes.…”