AUTHOR=Wang Lei , Yang Huansen , Wang Kun , Yang Haitao , Zhao Mengdi , Shang Yuping , Wang Fang , Dong Jingquan , Zhao Weiguo , Li Li , Liang Wei , Wang Yan 

TITLE=A Visualized Isothermal Amplification Method for Rapid and Specific Detection of Emetic and Non-emetic Bacillus cereus in Dairy Products

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.802656

DOI=10.3389/fmicb.2022.802656

ISSN=1664-302X

ABSTRACT=<p><italic>Bacillus cereus</italic> is widely distributed in foods, especially dairy products, and can lead to diarrhea (non-emetic <italic>B. cereus</italic>) and emesis (emetic <italic>B. cereus</italic>). Although diarrhea due to <italic>B</italic>. <italic>cereus</italic> is usually mild, emesis can lead to acute encephalopathy and even death. To develop rapid and sensitive detection methods for <italic>B. cereus</italic> in foods, specific primers targeting the <italic>gyrase B</italic> (<italic>gyrB</italic>) and cereulide synthetase (<italic>ces</italic>) genes were designed and screened using recombinase polymerase amplification (RPA). Probes and base substitutions were introduced to improve specificity and eliminate primer-dependent artifacts. The 5′ ends of the reverse primers and probes were modified with biotin and fluorescein isothiocyanate for detection of RPA products on a lateral flow strip (LFS). The developed RPA-LFS assay allows detection within 20 min at 37°C with no cross-reactivity with other foodborne pathogens. The limit of detection was 10<sup>4</sup> copies/ml and 10<sup>2</sup> CFU/ml in pure cultures and milk, respectively. Comparisons with established methods using cream obtained similar results. A specific, rapid, and sensitive RPA-LFS assay was successfully developed for on-site detection of <italic>B. cereus</italic> in dairy products to distinguish emetic from non-emetic strains.</p>