Description of Sporanaerobium hydrogeniformans gen. nov., sp. nov., an obligately anaerobic, hydrogen-producing bacterium isolated from Aravali hot spring in India

An obligately anaerobic bacterium XHS1971 T , capable of degrading cellulose and xylan, was isolated from a sediment sample of Aravali hot spring, Ratnagiri, India. Cells of strain XHS1971 T were Gram-stain-negative, spore-forming, motile, long-rods. Growth was observed at temperatures 30–50 °C (optimum 40–45 °C), pH 5.0–10.0 (optimum pH 8.0) and NaCl concentrations 0–0.5% (optimum 0%). Generation time of strain XHS1971 T was 5 h under optimised growth conditions. Strain XHS1971 T showed the ability to metabolise different complex and simple sugars constituting lignocellulosic biomass. Glucose was fermented majorly into hydrogen, formic acid, acetic acid, and ethanol, whereas carbon dioxide, butyric acid, lactic acid and succinic acid were produced in traces. 16S rRNA gene analysis of strain XHS1971 T revealed < 94.5% homology with Cellulosilyticum lentocellum DSM5427 T followed by Cellulosilyticum ruminicola JCM14822 T , identifying strain as a distinct member of family Lachnospiraceae . The major cellular fatty acids (> 5%) were C 14:0 , C 16:0 , C 18:0 , and C 16:1 ω7 c . The genome size of the strain was 3.74 Mb with 35.3 mol% G + C content, and genes were annotated to carbohydrate metabolism, including genes involved in the degradation of cellulose and xylan and the production of hydrogen, ethanol and acetate. The uniqueness of strain was further validated by digital DNA-DNA hybridisation (dDDH), Average Nucleotide Identity (ANI), and Average Amino Acid Identity (AAI) values of 22%, 80%, and 63%, respectively, with nearest phylogenetic affiliates. Based on the detailed analyses, we propose a new genus and species, Sporanaerobium hydrogeniformans gen. nov., sp. nov., for strain XHS1971 T (= MCC3498 T = KCTC15729 T = JCM32657 T ) within family Lachnospiraceae .