development of a specific real-time pcr assay targeting the poly-γ-glutamic acid synthesis gene, pgsb, for the quantification of bacillus amyloliquefaciens in solid-state fermentation

a taqman real-time pcr procedure was developed for specific detection and quantification of strains belonging to bacillus amyloliquefaciens group. the primer pair pgsb726-f/pgsb791-r and the pgsb-probe were designed from one of the poly-γ-glutamic acid synthesis gene (pgsb) of b. amyloliquefaciens. the detection limit was approximately between 10²–10³ cells/ml. a linear correlation between the log10 input pmd–pgsb plasmid dna copies and the threshold cycle values were observed with a magnitude of linearity in the range of 9.415 × 10³–10⁷ copies/ml for the standard curve, which exhibited a slope of −3.35 and an r² value of 99.8%. results of validation of this method with artificially contaminated and natural solid-state fermentation samples showed that it was suitable for specific and sensitive detection and quantification for the target strains in solid-state fermentation samples. this could be more useful to understand the fermentation starting strain and the final microbiological properties of fermentation products.