Halanaerobium sehlinense sp. nov., an extremely halophilic, fermentative, strictly anaerobic bacterium from sediments of the hypersaline lake Sehline Sebkha

Abstract

A strictly anaerobic, extremely halophilic, Gram-positive, rod-shaped bacterium was isolated from the hypersaline (>20 % NaCl) surface sediments of Sehline Sebkha in Tunisia. The strain, designated 1SehelT, was strictly halophilic and proliferated at NaCl concentrations of between 5 % and 30 % (saturation), with optimal growth at 20 % NaCl. Strain 1SehelT was non-spore-forming, non-motile, appearing singly or in pairs, or occasionally as long chains and measured 0.5–0.8 µm by 3–10 µm. Strain 1SehelT grew optimally at pH values of 7.4 but had a very broad pH range for growth (pH 5.2–9.4). It grew at temperatures between 20 and 50 °C with an optimum at 43 °C. Strain 1SehelT required yeast extract for growth. The isolate fermented glucose, galactose, fructose, glycerol, mannose, maltose, ribose, pyruvate and sucrose. The fermentation products from glucose utilization were lactate, acetate, formate, ethanol, CO2 and H2. The G+C ratio of the DNA was 32.7 mol%. The major fatty acids were C15 : 1ω6c/7c, C16 : 1ω7c, C16 : 0 and C15 : 0. On the basis of phylogenetic and physiological properties, strain 1SehelT ( = DSM 25582T = JCM 18213T) is proposed as the type strain of Halanaerobium sehlinense sp. nov., within the family Halanaerobiaceae .