Desulfosporosinus sediminicola sp. nov., an acidophilic sulfate-reducing bacterium isolated from acidic sediments of a disused iron mine site

An anaerobic, Gram-stain-positive and spore-forming acidophilic sulfate-reducing bacterium, designated as SYSU MS00001^T, was isolated from acidic sediments of Zhongshan Iron Mine, P.R. China. The strain was straight-rod-shaped and motile, oxidase-negative and catalase-negative, with circular, convex, regular-edged and black-pigmented colonies (1–3 mm in diameter) on the solid basal salts/yeast extract plate. Growth and proliferation occurred at 10–40 °C (optimal: 30 °C), pH 3.5–7.5 (optimal: 5.0–5.5) and NaCl concentration of 0–1.6% (optimal: 0.2%), with a doubling time of 8.2 h under the optimal conditions. The strain utilised H₂/CO₂, organic acids (fumarate, citrate, pyruvate, malate, acetate, propionate, lactate, butyrate), alcohols (glycerol), and sugars (fructose, glucose, xylose) as electron donors for sulfate reduction. Sulfate, sulfur, sulfite, thiosulfate, fumarate and nitrate were used as electron acceptors in the presence of glycerol. It also fermented ethanol and methanol without sulfate. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified phospholipids, unidentified aminophospholipid, unidentified lipids and unidentified glycolipids. The major fatty acids (> 5%) were C_14:0, C_16:0 and summed features 3 (C_16:1ω7c/C_16:1ω6c). The respiratory quinones identified were MK-7 and MK-8(H₄). Phylogenetic analyses based on 16S rRNA gene and genome sequences indicated that the isolated strain should be assigned to the genus Desulfosporosinus, and the 16S rRNA gene sequence was most closely related to Desulfosporosinus acididurans M1^T with similarity of 98.34%. The genomic DNA G + C content of SYSU MS00001^T was 41.7%. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between SYSU MS00001^T and D. acididurans M1^T were 50.6% and 90.95%, respectively. On the basis of phenotypic, phylogenetic and genetic characteristics, strain SYSU MS00001^T represents a novel species within the genus Desulfosporosinus, for which the name Desulfosporosinus sediminicola sp. nov. is proposed. The type strain is SYSU MS00001^T (= GDMCC 1.4736 ^T = KCTC 25900 ^T).