Physiological and comparative proteomic characterization of Desulfolithobacter dissulfuricans gen. nov., sp. nov., a novel mesophilic, sulfur-disproportionating chemolithoautotroph from a deep-sea hydrothermal vent

In deep-sea hydrothermal environments, inorganic sulfur compounds are important energy substrates for sulfur-oxidizing, -reducing, and -disproportionating microorganisms. Among these, sulfur-disproportionating bacteria have been poorly understood in terms of ecophysiology and phylogenetic diversity. Here, we isolated and characterized a novel mesophilic, strictly chemolithoautotrophic, diazotrophic sulfur-disproportionating bacterium, designated strain GF1(T), from a deep-sea hydrothermal vent chimney at the Suiyo Seamount in the Izu-Bonin Arc, Japan. Strain GF1(T) disproportionated elemental sulfur, thiosulfate, and tetrathionate in the presence of ferrihydrite. The isolate also grew by respiratory hydrogen oxidation coupled to sulfate reduction. Phylogenetic and physiological analyses support that strain GF1(T) represents the type strain of a new genus and species in the family Desulfobulbaceae, for which the name Desulfolithobacter dissulfuricans gen. nov. sp. nov. is proposed. Proteomic analysis revealed that proteins related to tetrathionate reductase were specifically and abundantly produced when grown via thiosulfate disproportionation. In addition, several proteins possibly involved in thiosulfate disproportionation, including those encoded by the YTD gene cluster, were also found. The overall findings pointed to a possible diversity of sulfur-disproportionating bacteria in hydrothermal systems and provided a refined picture of microbial sulfur disproportionation.

Automated summary

A novel mesophilic sulfur-disproportionating bacterium named Desulfolithobacter dissulfuricans was isolated from a deep-sea hydrothermal vent chimney in the Izu-Bonin Arc, Japan. This bacterium is able to disproportion elemental sulfur, thiosulfate, and tetrathionate in the presence of ferrihydrite, as well as grow via respiratory hydrogen oxidation coupled to sulfate reduction. Proteomic analysis revealed specific and abundant production of proteins related to tetrathionate reductase during thiosulfate disproportionation. This study provides insights into the diversity of sulfur-disproportionating bacteria in hydrothermal systems.