Staleya guttiformis gen. nov., sp nov and Sulfitobacter brevis sp nov., alpha-3-Proteobacteria from hypersaline, heliothermal and meromictic antarctic Ekho Lake

Two Gram-negative, aerobic, pointed and budding bacteria were isolated from various depths of hypersaline, heliothermal and meromictic Ekho Lake (Vest fold Hills, East Antarctica). 16S rRNA gene sequence comparisons show the i solates to be phylogenetically close to the genera Sulfitobacter and Roseob acter. Cells can be motile and contain storage granules. Sulfite addition d oes not stimulate growth. Isolate EL-38(T) can produce bacteriochlorophyll a and has a weak requirement for sodium ions; polar lipids include phosphat idylglycerol. phosphatidylchaline, phosphatidylethanolamine and an unidenti fied amino lipid, but not dilphosphatidylgycerol. The dominant fatty acid i s 18:1 omega 7c; other characteristic fatty acids are 3-OH 10:0, 3-OH 14:1, 16:0, 18:0, 18:2 and 19:1. The DNA base composition is 55.0-56.3 mol% G+C. Isolate EL-162(T) has an absolute requirement for sodium ions. Diphosphati dylglycerol, phosphatidylglycerol. phosphatidylcholine, phosphatidylerthano lamine and an unidentified amino lipid are present in the polar lipids. Dom inant fatty acids of this isolate are 18:1 omega 7c and 18:1 omega 9e as we ll as 18:2 which is present as two isomers. Other characteristic fatty acid s are 3-OH 10:0, 3-OH 14:1, 16:0 and 18:0. The G+C content is 57 9-58 1 mol 9/0. Morphological, physiological and genotypic differences from related, t hus far known genera support the description of Staleya guttiformis gen, no v, and sp. nov. with EL-38(T) (= DSM 11458(T)) as the type strain and of Su lfitobacter brevis sp. nov, with the type strain EL-162(T)(= DSM 11493(T)).