Unique biomarkers as a potential predictive tool for differentiation of Bacillus cereus group based on real-time PCR.

ABSTRACT

The aim of the study was to develop unique biomarkers for qPCR detection of Bacillus cereus group. Clinical and soil isolates were identified by specifically designed biomarkers - Lipoprotein (OPL-114-lipo), Methyltransferase (MT-17) and S-layer homology domain protein (151-1BC). In order to design biomarkers, we used 120 bacterial strains grouped into B. cereus and non-Bacillus group. The B. cereus group was confirmed by 108 strains of B. cereus and B. thuringiensis (30 reference and 78 wild), along with 3 strains of B. mycoides, B. pseudomycoides, and B. weihenstephanensis; while the non-Bacillus group was composed of 9 Gram-positive and Gram-negative strains. Direct analysis of samples revealed specificity towards identification and characterization of B. cereus group. The newly developed markers OPL-114-lipo and MT-17 showed specificity of 95% and 81%, respectively in identification of B. cereus. They are efficient tools to identify contaminated sources and the degree of bacterial contamination. Environmental and food samples do not require band isolation, re-amplification, sequencing or sequence identification. Thus, reducing the time and cost of analysis. Hence, it will be an alternative approach to traditional culture methods. Commercial food processing industries will be able to employ these biomarkers specific for B. cereus group as a detection tool to reduce economic loss due to B. cereus contamination.