Prevalence of the Strains of <i>Bacillus cereus</i> Group in Artisanal Mexican Cheese

Abstract

<i>Bacillus cereus</i> is a microorganism associated with food poisoning. It has been found in products, such as milk and dairy products. The aim of this study was to isolate and identify <i>B. cereus</i> group strains in artisan cheeses sold in southwestern Mexico, as well as its toxigenic profile, its psychrophilic ability, and its biofilm production. <i>B. cereus</i> isolation was performed on Mannitol Yolk Polymyxin (MYP) agar and this was molecularly confirmed by the amplification of the <i>gyrB</i> gene. Polymerase chain reaction was used to determine the toxigenic profile, amplifying conserved regions of <i>hblABD</i> and <i>nheABC</i> operons, which code for the subunits of <i>Hbl</i> and <i>Nhe</i> toxins, respectively, as well as <i>ges</i> and <i>cytK</i> genes, which code for toxin cereulide and cytotoxin K (Cytk). Frequency of <i>B. cereus</i> contamination in artisan cheeses was 29.48% (23/78), and the bacterium was isolated in similar quantities in all types of products. All strains were amylase positive, and 60.86% (14/23) were able to produce biofilm; 91.30% (21/23) of the strains were psychrophilic. In most of the strains, at least one gene related to enterotoxins was identified (21/23). <i>B. cereus</i> strains in this study have a high toxigenic potential, which increases the risk of food poisoning due to the consumption of artisan cheeses made in Mexico.