AUTHOR=Wei Shuai , Chelliah Ramachandran , Park Byung-Jae , Kim Se-Hun , Forghani Fereidoun , Cho Min Seok , Park Dong-Suk , Jin Yong-Guo , Oh Deog-Hwan 

TITLE=Differentiation of Bacillus thuringiensis From Bacilluscereus Group Using a Unique Marker Based on Real-Time PCR

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00883

DOI=10.3389/fmicb.2019.00883

ISSN=1664-302X

ABSTRACT=<p>The efficiency of a novel biomarker (the transcriptional regulator, <italic>XRE</italic>) was tested and evaluated in differentiating <italic>Bacillus thuringiensis</italic> from <italic>Bacillus cereus</italic> group species in environmental and spiked samples based on PCR and real-time PCR. Totally 120 strains, representing two bacterial groups, <italic>B. cereus</italic> group and non-<italic>Bacillus</italic> sp., were used to evaluate the performance of <italic>XRE</italic> and crystal protein (<italic>cry</italic>2, an existing biomarker). Further, three diverse samples (kimbap, lettuce, and spinach) were inoculated with <italic>B. thuringiensis</italic> and prominent biomarkers <italic>XRE</italic> and <italic>cry</italic>2 were used as targets. Direct analysis of the detection results for the pure cultures of <italic>B. cereus</italic> group wild-types, references and type strains revealed an accuracy rate of 97.5% targeting <italic>XRE</italic>, and 83.3% targeting <italic>cry</italic>2. The real-time PCR was constructed with a <italic>R</italic><sup>2</sup>-value of 0.993. For the artificially contaminated samples, a concentration of 10<sup>3</sup> CFU/g of <italic>B. thuringiensis</italic> in spiked food samples could be detected using real-time PCR targeting <italic>XRE.</italic> A good performance was obtained with <italic>XRE</italic> in discriminating <italic>B. thuringiensis</italic> from <italic>B. cereus</italic> groups, as well as detecting <italic>B. thuringiensis</italic> in spiked food samples with PCR or real-time PCR. Therefore, this real-time PCR targeting X<italic>RE</italic> can be used as a dependable and promising tool to identify <italic>B. thuringiensis</italic> in foods.</p>