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-6 T clustered together with other species of the genus Bacillus and showed highest similarities with Bacillus drentensis LMG 21831 T (99.1 %), Bacillus vireti LMG 21834 T (98.7 %) and Bacillus soli LMG 21838 T (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-C 15 : 0 , iso-C 15 : 0 and C 16 : 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 21831 T , B. vireti LMG 21834 T and B. soli LMG 21838 T 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-6 T represents a novel species of the genus Bacillus , for which the name Bacillus cucumis sp. nov. is proposed, with AP-6 T ( = CIP 110974 T  = CCM 8651 T ) as the type strain.