Bacillus mexicanus sp. nov., a biological control bacterium isolated from the common bean (Phaseolus vulgaris L.) crop in Sinaloa, Mexico.

Abstract

Strain FSQ1T was isolated from the rhizosphere of the common bean (Phaseolus vulgaris L.) crop sampled in a commercial field located in the Gabriel Leyva Solano community, which belongs to the Guasave municipality (state of Sinaloa, Mexico). Based on its full-length 16S rRNA gene sequence, strain FSQ1T was assigned to the genus Bacillus (100 % similarity). This taxonomic affiliation was supported by its morphological and metabolic traits. Strain FSQ1T was a Gram-stain-positive bacterium with the following characteristics: rod-shaped cells, strictly aerobic, spore forming, catalase positive, reduced nitrate to nitrite, hydrolysed starch and casein, grew in the presence of lysozyme and 2 % NaCl, utilized citrate, grew at pH 6.0-8.0, produced acid from glucose, was unable to produce indoles from tryptophan, and presented biological control against Sclerotinia sclerotiorum. The whole-genome phylogenetic results showed that strain FSQ1T formed an individual clade in comparison with highly related Bacillus species. In addition, the maximum values for average nucleotide identity and from Genome-to-Genome Distance Calculator analysis were 91.57 and 44.20 %, respectively, with Bacillus spizizenii TU-B-10T. Analysis of its fatty acid content showed the ability of strain FSQ1T to produce fatty acids that are not present in closely related Bacillus species, such as C18 : 0 and C20 : 0. Thus, these results provide strong evidence that strain FSQ1T represents a novel species of the genus Bacillus, for which the name Bacillus mexicanus sp. nov. is proposed. The type strain is FSQ1T (CM-CNRG TB51T=LBPCV FSQ1T).