Fuchsiella alkaliacetigena gen. nov., sp. nov., an alkaliphilic, lithoautotrophic homoacetogen from a soda lake

The first alkaliphilic obligately anaerobic hydrogenotrophic homoacetogenic bacterium, strain Z-7100T, was isolated from sediments of the soda-depositing soda lake Tanatar III (Altay, Russia). Cells were thin, flexible rods, motile, Gram-negative and spore-forming. The organism was an obligate alkaliphile, growing at pH 8.5 to 10.5, with optimum growth at pH 8.8–9.3, and it grew in soda brines containing 1.9–4.7 M total Na+ (optimum at 2.8–3.3 M). It exhibited an obligate dependence upon sodium carbonate but not upon chloride ions with an NaCl range for growth of 0–14 % (w/v) and an optimum at 7.0–8.5 % (w/v). The isolate was mesophilic and grew at temperatures from 25 to 45 °C, with an optimum at 40 °C. An H2+CO2 mixture, ethanol, pyruvate and lactate were utilized with the formation of acetate as the sole metabolic product. Carbohydrates and amino acids did not support growth. The isolate had a respiratory type of metabolism, reducing [Formula], SeO42− or anthraquinone-2,6-disulfonate (as electron acceptors with ethanol as an electron donor). It was able to grow chemolithotrophically on H2+CO2 in medium supplemented with a vitamin solution only. The major cellular fatty acids were the saturated fatty acids anteiso-C15, C14 : 0 and C16 : 0 and the aldehydes C16, C14 and anteiso-C15. The DNA G+C content of the isolate was 32.0 mol%. 16S rRNA gene sequence analysis showed that strain Z-7100T is a member of the order Halanaerobiales and represents a new branch within the family Halobacteroidaceae, clustering with the type strain of Selenihalanaerobacter shriftii (92.9 % gene sequence similarity). On the basis of its physiological characteristics and phylogenetic position, the isolate is considered to represent a novel species in a new genus within the family Halobacteroidaceae. The name Fuchsiella alkaliacetigena gen. nov., sp. nov. is proposed. The type strain of the type species is Z-7100T ( = DSM 24880T = VKM B-2667T).