Two alkaliphilic and moderately halophilic bacterial strains B16-10T and Z23-18 characterized by optimal growth at pH 9.0-10.0 and 5 % (w/v) NaCl, were isolated from the rhizosphere soil of the bayonet grass (Bolboschoenus maritimus) in the Kiskunság National Park, Hungary. Cells of both strains stained Gram-positive, were motile straight rods, and formed terminal, ellipsoidal endospores with swollen sporangia. The isolates were facultative anaerobic, catalase positive, oxidase negative. Both strains contained meso-diaminopimelic acid as diagnostic diaminoacid of the peptidoglycan. Menaquinone-7 (MK-7) was the predominant isoprenoid quinone. Anteiso-C15 : 0, C16 : 1ω11c and iso-C14 : 0 were the major cellular fatty acids. The DNA G+C content of both strains was 35.8 mol%. The 16S rRNA gene based phylogenetic analysis revealed that the facultative anaerobic strains B16-10T and Z23-18 showed the highest similarities to the type strains of anaerobic Anaerobacillus isosaccharinicus NB2006T (98.7 and 99.1 %), A. macyae JMM-4T (98.2 and 98.4 %), A. alkalidiazotrophicus MS 6T (97.7 and 98.4 %), A. alkalilacustris Z-0521T (97.5 and 98.3 %) and A. arseniciselenatis DSM 15340T (97.5 and 98.2 %). However, the distinctive phenotypic and genetic results of this study confirmed that strains B16-10T and Z23-18 represent a novel species, for which the name Anaerobacillus alkaliphilus sp. nov. is proposed. The type strain is B16-10T (=DSM 29790T=NCAIM B 02608T).
Keywords: Anaerobacillus; alkaliphilic and moderately halophilic bacterium; soda soil.