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-LU (and related strains) and JW/NM-WN-LH1 were non-spore-forming, non-motile bacteria with a Gram-type positive cell wall. Optimal growth of strain JW/NM-WN-LU occurred at pH 9.5, 52 °C and with 3.7 M Na (2.2 M added NaCl). Optimal growth of strain JW/NM-WN-LH1 occurred at pH 9.9, 51 °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-LU and JW/NM-WN-LH1 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 within the order . Based on genotypic and phenotypic data, strain JW/NM-WN-LU (=DSM 18760=ATCC BAA-1443) represents the type strain of a novel species, sp. nov. Strain JW/NM-WN-LH1 represents a novel genus and species within the family , gen. nov., sp. nov. The type strain of the type species is JW/NM-WN-LH1 (=DSM 18770=ATCC BAA-1444).


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