Bacillus alkalisediminis sp. nov., an alkaliphilic and moderately halophilic bacterium isolated from sediment of extremely shallow soda ponds

Abstract

Alkaliphilic strains characterized by optimal growth at pH 9.0 and 5 % (w/v) NaCl designated K1-25T and H3-93 were isolated from extremely shallow soda ponds located in Hungary. Cells of both strains were Gram-stain-positive, non-motile, straight rods and formed central, ellipsoidal endospores with swollen sporangia. The isolates were aerobic, catalase-positive, oxidase-negative and contained a peptidoglycan of type A1γ based on meso-diaminopimelic acid. In both strains, menaquinone-7 (MK-7) was the predominant isoprenoid quinone and the major cellular fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The DNA G+C contents of strains K1-25T and H3-93 were 39.0 and 36.3 mol%, respectively. 16S rRNA gene sequence-based phylogenetic analysis revealed 99.2 % similarity between strains K1-25T and H3-93 and the novel isolates had the highest similarities to Bacillus akibai 1139T (97.8 and 98.3 %, respectively), Bacillus wakoensis N-1T (97.0 and 97.4 %), Bacillus okhensis Kh10-101T (97.1 and 97.4 %) and Bacillus krulwichiae AM31DT (96.9 and 97.1 %). DNA–DNA hybridization between our strains and the type strains of closely related Bacillus species was lower than 70 %. Although DNA–DNA hybridization between strains K1-25T and H3-93 was 27 %, the phenotypic and chemotaxonomic data did not support the differentiation of these two strains into separate species. Therefore, they represent genomovars of a novel species, for which the name Bacillus alkalisediminis sp. nov. is proposed. The type strain is K1-25T ( = DSM 21670T  = NCAIM B02301T).