Phylogenomic analysis shows that ‘Bacillus vanillea’ is a later heterotypic synonym of Bacillus siamensis

‘Bacillus vanillea’ XY18 ( = CGMCC 8629 = NCCB 100507) was isolated from cured vanilla beans and involved in the formation of vanilla aroma compounds. A draft genome of this strain was assembled and yielded a length of 3.71 Mbp with a DNA G+C content of 46.3 mol%. Comparative genomic analysis with its nearest relatives showed only minor differences between this strain and the genome of the Bacillus siamensis KCTC 13613T ( = BCC 22614T = KACC 16244T), with a calculated DNA–DNA hybridization (DDH) value of 91.2 % and an average nucleotide identity (ANI) of 98.9 %. This DDH value is well above the recommended 70 % threshold for species delineation, as well as the ANI threshold of 95 %. In addition, the results of morphological, physiological, chemotaxonomic and phylogenetic analyses indicate that the type strains of these two taxa are highly similar with phenotype coherence. A core genome multi-locus sequencing analysis was conducted for the strains and the results show that ‘Bacillus vanillea’ XY18 clusters closely to the type strain of Bacillus siamensis. Therefore, it is proposed that the species ‘Bacillus vanillea’ XY18 ( = CGMCC 8629 = NCCB 100507) should be reclassified as a later heterotypic synonym of Bacillus siamensis KCTC 13613T ( = BCC 22614T = KACC 16244T). An emended description of Bacillus siamensis is provided.