Sulfurimonas autotrophica gen. nov., sp. nov., a novel sulfur-oxidizing {varepsilon}-proteobacterium isolated from hydrothermal sediments in the Mid-Okinawa Trough

Researchers isolated a novel sulfur-oxidizing bacterium, strain OK10T, from deep-sea hydrothermal sediments at Hatoma Knoll in the Mid-Okinawa Trough. The organism is a mesophilic, motile Gram-negative rod belonging to the epsilon-Proteobacteria. It grows chemolithoautotrophically using elemental sulfur, sulfide, and thiosulfate as electron donors, with oxygen as the electron acceptor. The bacterium thrives at temperatures of 10–40°C (optimum 25°C) and pH 4.5–9.0 (optimum 6.5), requires sea salts for growth, and shows optimal growth in 5–8% oxygen. With a genomic DNA G+C content of 35.2 mol%, phylogenetic analysis based on 16S rRNA gene sequences places it within epsilon-Proteobacteria Group B, the most predominant phylotype in low-temperature hydrothermal microhabitats. The authors propose strain OK10T as the type species of a new genus, Sulfurimonas autotrophica. This isolate likely represents one of the most abundant sulfur-cycling microorganisms in global deep-sea hydrothermal systems.

Key findings

• Sulfurimonas autotrophica is a novel mesophilic, aerobic, chemolithoautotrophic sulfur-oxidizing bacterium isolated from deep-sea hydrothermal sediments
• The organism oxidizes sulfide, elemental sulfur, and thiosulfate to sulfate, using only oxygen as an electron acceptor, with optimal growth at 5–8% O2
• Phylogenetic analysis reveals strain OK10T belongs to epsilon-Proteobacteria Group B, the most abundant bacterial phylotype in low-temperature hydrothermal vent environments globally
• The organism cannot grow on organic substrates or hydrogen, is strictly aerobic, and requires marine salts for growth, with optimal conditions at 23–26°C and pH 6.0–7.5