Characterization of <i>Bacillus</i> Species from Market Foods in Beijing, China

• Main Authors: Qiao Hu, Yuwen Fang, Jiajia Zhu, Wenjiao Xu, Kui Zhu
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Processes
• Subjects: emerging foodborne pathogens; <i>Bacillus</i>; probiotics; antimicrobial resistance
• Online Access: https://www.mdpi.com/2227-9717/9/5/866

Foodborne diseases have been witnessing a constant rising trend worldwide, mainly caused by pathogenic microorganisms, such as <i>Bacillus</i> spp., posing a direct threat to public health. The purpose of this study was to evaluate the biological risk of foodborne and probiotic <i>Bacillus</i> spp. in Beijing markets. A total of 55 <i>Bacillus</i> isolates, including 29 <i>B. cereus</i>, 9 <i>B. licheniformis</i> and 7 <i>B. subtilis</i>, mostly found in dairy products (32.7%), were recovered from 106 samples and identified by matrix-assisted laser desorption/ionization mass spectrometry and polymerase chain reaction methods. The susceptibility towards 16 antibiotics was determined using a broth microdilution method. <i>Bacillus</i> showed a high level of resistance to florfenicol (100%), lincomycin (100%), tiamulin (78.2%) and ampicillin (67.3%), while they were all susceptible or intermediate to vancomycin and rifampin. Additionally, we obtained the whole genome of 19 <i>Bacillus</i> strains using high-throughput sequencing, and the rates of resistance genes <i>van</i>, <i>fosB</i>, <i>erm</i> and <i>tet</i> were 57.9%, 57.9%, 21.1% and 26.3%, respectively. Moreover, 100%, 9.1%, 45.5% and 100% of these isolates carried virulence genes <i>nhe</i>, <i>hbl</i>, <i>cytK</i> and <i>entFM</i>, respectively. Lastly, 60% <i>Bacillus</i> strains were positive in hemolysis tests, and 3 <i>B. licheniformis</i> strains displayed an inhibitory activity on the growth of <i>S. aureus</i> ATCC 29213 using agar overlay technique. Our study outlines the characteristics of foodborne <i>Bacillus</i> spp. and provides information for the monitoring of food safety.