Attachment of Bacillus cereus spores with and without appendages to stainless steel surfaces

Bacillus cereus is an important cause of bacterial food poisoning. It is a spore former and the spores attach easily to stainless steel surfaces. The spores have long appendages and it is believed that these play an important role in the attachment to surfaces. In this study, spores of three different strains (NVH 74, NVH 1230-88 and IAM 1110) where the appendages had been removed by ultrasonication, were compared with the native spores with respect to the ability to attach to stainless steel and polypropylene surfaces. Both static conditions and fluid flow conditions were studied. Under static conditions, the attachment of the native spores to the surface was slightly, but significantly, higher than the attachment of the same spores without appendages. Under fluid flow conditions, however, for NVH 74 and IAM 1110 spores without appendages seemed to adhere slightly better to the surface than native spores. For NVH 1230-88, spores without appendages adhered very poorly to the surface compared with native spores. The results indicate that the importance of the appendages in the attachment of Bacillus cereus spores to surfaces may depend both upon the strain and the hydrodynamic conditions under which the attachment takes place.