Alkalitalea saponilacus gen. nov., sp. nov., an obligately anaerobic, alkaliphilic, xylanolytic bacterium from a meromictic soda lake

A Gram-positive, obligately anaerobic, motile, slender, flexible rod, designated SC/BZ-SP2T, was isolated from mixed alkaline water and sediment of Soap Lake, Washington State, USA. Strain SC/BZ-SP2T formed salmon to pink colonies and was alkaliphilic. The isolate grew at pH35 °C 7.5–10.5 (optimum pH35 °C 9.7), at 8–40 °C (optimum 35–37 °C) and with 0.35–1.38 M Na+ (optimum 0.44–0.69 M Na+). The isolate utilized l-arabinose, d-ribose, d-xylose, d-fructose, d-mannose, d-galactose, cellobiose, maltose, sucrose, trehalose, sorbitol, xylan, malate and yeast extract as carbon and energy sources; best growth was observed with l-arabinose, cellobiose, maltose and trehalose. The major fermentation products from beechwood xylan were propionate and acetate. The dominant fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0 3-OH, C17 : 0 3-OH and C15 : 0 3-OH. The cell-wall sugars were ribose, xylose, galactose and glucose. Thiosulfate and sulfite could be reduced to sulfide. The genomic DNA G+C content was 39.5±0.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SC/BZ-SP2T belonged to the family Marinilabiliaceae of the order Bacteroidales, class Bacteroidia. The most closely related strains were Alkaliflexus imshenetskii Z-7010T (91.8 % 16S rRNA gene sequence similarity), Marinilabilia salmonicolor Cy s1T (91.0 %) and Anaerophaga thermohalophila Fru22T (90.4 %). On the basis of phenotypic, chemotaxonomic and phylogenetic features, strain SC/BZ-SP2T represents a novel species in a new genus of the family Marinilabiliaceae, for which the name Alkalitalea saponilacus gen. nov., sp. nov. is proposed. The type strain of Alkalitalea saponilacus is SC/BZ-SP2T ( = ATCC BAA-2172T = DSM 24412T).