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-SP2(T), was isolated from mixed alkaline water and sediment of Soap Lake, Washington State, USA. Strain SC/BZ-SP2(T) formed salmon to pink colonies and was alkaliphilic. The isolate grew at pH(35 °C) 7.5-10.5 (optimum pH(35 °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-C(15:0), anteiso-C(15:0), iso-C(17:0) 3-OH, C(17:0) 3-OH and C(15:0) 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-SP2(T) belonged to the family Marinilabiliaceae of the order Bacteroidales, class Bacteroidia. The most closely related strains were Alkaliflexus imshenetskii Z-7010(T) (91.8% 16S rRNA gene sequence similarity), Marinilabilia salmonicolor Cy s1(T) (91.0%) and Anaerophaga thermohalophila Fru22(T) (90.4%). On the basis of phenotypic, chemotaxonomic and phylogenetic features, strain SC/BZ-SP2(T) 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-SP2(T) (=ATCC BAA-2172(T) =DSM 24412(T)).