INFLUENCE OF ENVIRONMENTAL-STRESS ON THE KINETICS AND STRENGTH OF ATTACHMENT OF LISTERIA-MONOCYTOGENES SCOTT-A TO BUNA-N RUBBER AND STAINLESS-STEEL

Attachment and detachment of Listeria monocytogenes Scott A to Buna-N rubber and stainless steel under varying conditions of temperature and pH were investigated using model systems. Numbers of attached cells i ncreased with increasing attachment temperature (10 to 45 degrees C) a nd time (up to 120 min) for both test surfaces. Compared to Buna-N rub ber, the rate of attachment to stainless steel was markedly more rapid for all temperature and pH conditions studied and could not be calcul ated, Rate of attachment to Buna-N rubber was found to be significantl y lower when cells were attached at 10 degrees C. Growth temperature d id not significantly affect rates of adhesion to Buna-N rubber. Alteri ng the medium pH during attachment between 4 and 9 demonstrated that r ates of adhesion were slower under all;aline conditions. Growth pH was also found to significantly affect rates of attachment to Buna-N rubb er. Detachment of cells adhered to Buna-N rubber was significantly aff ected by growth temperature but not growth pH. Significant differences in detachment were also found between Buna-N rubber and stainless ste el, inferring stronger attachment to Buna-N rubber. Cell surface hydro phobicity was found to be affected by both growth temperature and grow th pH. However, changes in hydrophobicity could not be correlated to d ifferences in rates of attachment. Addition of 0.01% trypsin to the at tachment medium during cell exposure to either test surface resulted i n a 99.9% reduction in the adhered cell population when compared to co ntrols. This would suggest that proteins play a role in the initial at tachment process of L. monocytogenes.