Bacillus cabrialesii subsp. cabrialesii subsp. nov. and Bacillus cabrialesii subsp. tritici subsp. nov., plant growth- promoting bacteria and biological control agents isolated from wheat (Triticum turgidum subsp. durum) in the Yaqui Valley, Mexico

Strain TSO2(T), a plant growth- promoting rhizobacteria and biological control agent, was isolated from wheat rhizosphere sampled from the Yaqui Valley in Mexico. The strain was identified using a polyphasic approach. Based on its analysis of the full- length 16S rRNA gene, strain TSO2(T) was assigned to the genus Bacillus, which was supported by morphological and metabolic traits, such as Gram- positive staining, rod shape, spore formation, strictly aerobic metabolism, catalase- positive activity, starch, and casein hydrolysis, reduction of nitrate to nitrite, growth in presence of lysozyme and 2 % NaCl, citrate utilization, growth at pH 6.0, acid production from glucose and indole production from tryptophan. Additionally, strain TSO2(T) possesses swarming motility, presenting a featureless mat pattern that can cover the whole petri dish. The whole- genome phylogenetic relationship analysis elucidated that strain TSO2(T) is closely related to Bacillus cabrialesii TE3(T). The maximum values for average nucleotide identity (ANI) and in silico DNA-DNA hybridization from the genome- to- genome distance calculator (GGDC) were 97 and 73.4 %, respectively, related to Bacillus cabrialesii TE3(T), where both ANI and GGDC values were barely above the species delimitation threshold, but below the subspecies limit. Also, strain TSO2T showed the ability to produce a fatty acid (C18:0) that is not present in closely related Bacillus species. These results provide evidence that strain TSO2(T) is a novel subspecies of the species Bacillus cabrialesii, for which the name Bacillus cabrialesii subsp. tritici subsp. nov. is proposed. The type strain of Bacillus cabrialesii subsp. tritici subsp. nov. is TSO2(T) (CM-CNRG TB52(T)=LBPCV TSO2(T)). The description of this novel subspecies automatically creates the subspecies Bacillus cabrialesii subsp. cabrialesii subsp. nov. for which the type strain is TE3(T) (CM-CNRG TB54(T)=CCStamb A1(T)).