Food Safety and Health

Biography

Biography: Nassima Didouh

Abstract

Bacillus cereus is an endospore-forming bacterium frequently found in dairy products and dairy environment. In fact their spores have great ability to adhere to surfaces, in particular to hydrophobic surfaces and produce many toxins. Th e most B. cereus spores studied has been shown to be generally strongly hydrophobic. Many studies have shown a relationship between the bacterial spore characteristics and its ability to adhere to surfaces. In this study, molecular identifi cation (M13 RAPD, Rep PCR, PFGE), toxicogenic and physicochemical characterization of 14 Bacillus cereus strains isolated from a dairy plant located in north-western Algeria were studied using Microbial Adhesion To Hydrocarbon (MATH) method, and zeta potential measurements, respectively. Twelve (12) strains belong to Bacillus cereus group III and the two other to Bacillus cereus group IV. Spores of 11 strains presented a hydrophilic character and three a hydrophobic one. Th e spore zeta potential values for all strains were between 12.28 and -44, 51 mV. Four spore morphologies were investigated by Transmission Electron Microscopy (TEM) aft er negative staining. Th is allowed the clear observation of an exosporium surrounding all B. cereus spores. Th e ability of spores to adhere to stainless steel was also studied and varied among strains. Th e presence of an exosporium was not suffi  cient to explain the ability of spores to adhere to stainless steel surfaces. When physicochemical surface characters of B. cereus spores were compared the hydrophobicity, the appendages length, the surface of spore and exosporium were found as the signifi cant adhesion parameters.