Natronovirga wadinatrunensis gen. nov., sp. nov. and Natranaerobius trueperi sp. nov., halophilic, alkalithermophilic micro-organisms from soda lakes of the Wadi An Natrun, Egypt.

Novel strains of anaerobic, halophilic, alkalithermophilic bacteria were isolated from sediments of the alkaline, hypersaline lakes of the Wadi An Natrun, Egypt. Strains JW/NM-WN-LUT (and related strains) and JW/NM-WN-LH1T were non-spore-forming, non-motile bacteria with a Gram-type positive cell wall. Optimal growth of strain JW/NM-WN-LUT occurred at pH55 degrees C 9.5, 52 degrees C and with 3.7 M Na+ (2.2 M added NaCl). Optimal growth of strain JW/NM-WN-LH1T occurred at pH55 degrees C 9.9, 51 degrees C and with 3.9 M Na+ (2.3 M added NaCl). Both strains were obligately anaerobic and chemoorganotrophic; producing lactate and acetate as organic acids from pyruvate in different ratios. The DNA G+C contents of strains JW/NM-WN-LUT and JW/NM-WN-LH1T were 41.0 and 42.0 mol%, respectively. The main cellular fatty acids in both strains were anteiso-branched 15:0 and iso-branched 15:0. Phylogenetic analysis showed that both novel isolates belonged to the family Natranaerobiaceae within the order Natranaerobiales. Based on genotypic and phenotypic data, strain JW/NM-WN-LUT (=DSM 18760T=ATCC BAA-1443T) represents the type strain of a novel species, Natranaerobius trueperi sp. nov. Strain JW/NM-WN-LH1T represents a novel genus and species within the family Natranaerobiaceae, Natronovirga wadinatrunensis gen. nov., sp. nov. The type strain of the type species is JW/NM-WN-LH1T (=DSM 18770T=ATCC BAA-1444T).