Geosporobacter ferrireducens sp. nov., an anaerobic iron-reducing bacterium isolated from an oil-contaminated site

In this study, an alkaliphilic and heterotrophic iron-reducing bacterial strain, IRF9 T , was isolated from an oil-contaminated soil in the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain IRF9 T belongs to the genus Geosporobacter in the family Clostridiaceae and is most closely related to Geosporobacter subterraneus VNs68 T (96.9 % sequence similarity). Cells of strain IRF9 T were observed to be straight or curved rod-shaped, motile and Gram-negative. Optimal growth of strain IRF9 T was observed at pH 9.0–9.5 and 40 °C. The strain was found to grow within pH and temperature ranges of 6.5–10.0 and 25–45 °C, respectively. NaCl was not required for growth. Fe(III), but not sulfate, thiosulfate or elemental sulfur can be used by strain IRF9 T as an electron acceptor. A limited number of carbohydrates and amino acids, including d -glucose, d -fructose, d -mannitol, d -ribose and l -arginine, support growth of strain IRF9 T . The main fatty acids (>10 %) of strain IRF9 T were identified as C 14:0 (18.4 %), C 16:1 cis9 (13.6 %), C 16:0 (12.4 %) and C 16:0 dimethyl acetal (17.7 %). Major respiratory quinone was identified as menaquinone MK-5 (V-H 2 ). The main polar lipids were found to be phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The DNA G+C content of strain IRF9 T was determined to be 37.2 mol%, which is lower than that of G. subterraneus VNs68 T (42.2 mol%). Based on phenotypic, chemotaxonomic, and phylogenetic studies, we conclude that strain IRF9 T (=JCM 19987 T = KCTC 15395 T ) represents a new species of the genus Geosporobacter , for which we propose the name Geosporobacter ferrireducens sp. nov.