Physico-chemical surface characterization of Bacillus cereus spores isolated from an Algerian dairy plant

Bacillus cereus is an endospore-forming bacterium frequently found in dairy products and dairy environment. In this study, the hydrophobicity and surface electrical charge of spores from fourteen (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. Spores of eleven (11) strains presented a hydrophilic character and three (3) a hydrophobic one. The 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) after negative staining. This allowed the clear observation of an exosporium surrounding all B .cereus spores. The ability of spores to adhere to stainless steel was also studied and varied among strains. The presence of an exosporium was not sufficient to explain the ability of spores to adhere to stainless steel surfaces. When physico-chemical surface characters of B. cereus spores were compared: the hydrophobicity, the appendages length, the surface of spore and exosporium were found as the significant adhesion parameters.