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 1Sehel(T), was strictly halophilic and proliferated at NaCl concentrations of between 5% and 30% (saturation), with optimal growth at 20% NaCl. Strain 1Sehel(T) 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 1Sehel(T) 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 1Sehel(T) 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 C151ω6c/7c, C161ω7c, C160 and C150. On the basis of phylogenetic and physiological properties, strain 1Sehel(T) (=DSM 25582(T)=JCM 18213(T)) is proposed as the type strain of Halanaerobium sehlinense sp. nov., within the family Halanaerobiaceae.