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Abstract
This study was undertaken to determine the efficacies of different concentrations of cellulase or protease, 2% acetic and lactic acid and a manufacturer-recommended concentration of an acidic and alkaline detergent to reduce cellulose or curli, inactivate the cells of Shiga toxin producing Escherichia coli (STEC), and control the biofilms formed by STEC producing different amounts of cellulose and/or curli on polystyrene and stainless steel surfaces. It was found that treatments with 2% acetic and lactic acid significantly reduced the cell populations of STEC and the amounts of curli, and treatments with 2% lactic acid also significantly decreased the amounts o of cellulose produced by STEC cells (P < 0.05). The residual amounts of cellulose and curli after the treatments with the two organic acids positively correlated to the surviving cell populations of individual STEC strains used in the study. Treatments with cellulase and protease degraded cellulose and curli, respectively, but the treatments had no influence on the fate of STEC cells. Treatments with the two commercial detergents not only degraded cellulose and curli, but also reduced the cell populations of STEC to undetectable levels. Thus, no positive correlations between the residual a amounts of cellulose or curli and the surviving cell populations of STEC from the treatments with the two detergents was observed. Cells expressing cellulose and/or curli formed the greater amounts of biofilm. More dense of biofilms were formed on polystyrene than on stainless steel surface. Acidic and alkaline detergents were more effective than the organic acids in removing biofilms.