Desulfosporosinus paludis sp. nov., an acidotolerant sulphate-reducing bacterium isolated from moderately acidic fen soil

An obligately anaerobic, spore-forming sulphate-reducing bacterium, strain SB140^T, was isolated from a long-term continuous enrichment culture that was inoculated with peat soil from an acidic fen. Cells were immotile, slightly curved rods that stained Gram-negative. The optimum temperature for growth was 28 °C. Strain SB140^T grew at pH 4.0-7.5 with an optimum pH of 6.0-7.0 using various electron donors and electron acceptors. Yeast extract, sugars, alcohols and organic acids were used as electron donors for sulphate reduction. SB140^T additionally used elemental sulphur and nitrate as electron acceptors but not sulphite, thiosulphate or iron(III) provided as ferrihydrite and fumarate. The 16S rRNA gene sequence placed strain SB140^T in the genus <i>Desulfosporosinus</i> of the phylum <i>Bacillota</i>. The predominant cellular fatty acids were iso-C_{15 : 0} (52.6%) and 5,7 C_{15 : 2} (19.9%). The draft genome of SB140^T (5.42 Mbp in size) shared 77.4% average nucleotide identity with the closest cultured relatives <i>Desulfosporosinus acididurans</i> M1^T and <i>Desulfosporosinus acidiphilus</i> SJ4^T. On the basis of phenotypic, phylogenetic and genomic characteristics, SB140^T was identified as a novel species within the genus <i>Desulfosporosinus</i>, for which we propose the name <i>Desulfosporosinus paludis</i> sp. nov. The type strain is SB140^T (=DSM 117342^T=JCM 39521^T).