Characterization of Halanaerocella petrolearia gen. nov., sp. nov., a new anaerobic moderately halophilic fermentative bacterium isolated from a deep subsurface hypersaline oil reservoir New taxa: Firmicutes (Class Clostridia, Order Halanaerobiales, Halobacteroidaceae, Halobacteroides)

International audienceAn anaerobic, halophilic, and fermentative bacterium, strain S200T, was isolated from a core sample of a deep hypersaline oil reservoir. Cells were rod-shaped, non-motile, and stained Gram-positive. It grew at NaCl concentrations ranging from 6 to 26% (w/v), with optimal growth at 15% (w/v) NaCl, and at temperatures between 25 and 47°C with an optimum at 40-45°C. The optimum pH was 7.3 (range 6.2―8.8; no growth at pH 5.8 and pH 9). The doubling time in optimized growth conditions was 3.5 h. Strain S200T used exclusively carbohydrates as carbon and energy sources. The end products of glucose degradation were lactate, formate, ethanol, acetate, H2, and CO2. The predominant cellular fatty acids were non-branched fatty acids C16:1, C16:0, and C14:0. The G + C mole% of the DNA was 32.7%. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain S200T formed a distinct lineage within the family Halobacteroidaceae, order Halanaerobiales, and was most closely related to Halanaerobaculum tunisiense DSM 19997T and Halobacteroides halobius DSM 5150T, with sequence similarity of 92.3 and 91.9%, respectively. On the basis of its physiological and genotypic properties, strain S200T is proposed to be assigned to a novel species of a novel genus, for which the name Halanaerocella petrolearia is proposed. The type strain of Halanaerocella petrolearia is strain S200T (=DSM 22693T = JCM 16358T)