f Bacillus cucumis sp. nov. isolated from the rhizosphere of cucumber (Cucumis sativus)

A facultative anaerobic, Gram-positive staining, endospore-forming bacterium, isolated from the rhizosphere of cucumber (Cucumis sativus), was taxonomically investigated. Based on 16S rRNA gene sequence similarity comparisons, strain AP-6T clustered together with other species of the genus Bacillus and showed highest similarities with Bacillus drentensis LMG 21831T (99.1 %), Bacillus vireti LMG 21834T (98.7 %) and Bacillus soli LMG 21838T (98.5 %). The 16S rRNA gene sequence similarity to the sequences of the type strains of other species of the genus Bacillus was 98.5 % or less. Chemotaxonomic features supported the grouping of the strain in the genus Bacillus; for example, the major fatty acids were anteiso-C15 : 0, iso-C15 : 0 and C16 : 0, the polar lipid profile contained the major components diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified glycolipid, the major quinone was menaquinone MK-7 and the major compound in the polyamine pattern was spermidine. Additionally, DNA–DNA hybridization with B. drentensis LMG 21831T, B. vireti LMG 21834T and B. soli LMG 21838T resulted in relatedness values that were clearly below 70 %. Physiological and biochemical test results were also different from those of the most closely related species. As a consequence, AP-6T represents a novel species of the genus Bacillus, for which the name Bacillus cucumis sp. nov. is proposed, with AP-6T ( = CIP 110974T = CCM 8651T) as the type strain.