New realtime PCR method development for detection and quantification of Bacillus subtilis

Bacillus subtilis is a widely used bacterial strain in probiotic production. The strains belong to this species are endosporogenic, tolerant to acidic pH conditions in the stomach, and many have been shown to produce enzymes that aid in food digestion and inhibit pathogenic microorganisms. In this study, a detection and qualitification method was developed based on amplification of aprE gene ultilising realtime PCR. The aprE target gene encodes subtilisin toxin precursor and is a highly conservative and specific gene of B. subtilis. The method yielded high sensitivity with LOD is 102 (CFU/mL), LOQ is 102 (CFU/mL), specificity, and accuracy are both 100%. The preparatory tools were constructed using cycle threshold (Ct) compare with B. subtilis concentration, which showed linear correlation (R2 = 1, slope = - 3.584).