CONTROL OF THERMOPHILIC SPORES BY SPORICIDAL AGENTS AND THERMAL INACTIVATION

Abstract

In this study, the adhesion patterns of thermophilic spores of Geobacillus thermodenitrificans DSM 465^T, Geobacillus thermoglucosidans B84a, Anoxybacillus kamchatkensis subp. asaccharedens F81 and Anoxybacillus flavithermus DSM 2641^T, all of which are biofilm producers in dairy products, were investigated by epifluorescence microscopy on 6 different abiotic surfaces commonly used in the dairy industry. The spores of G. thermodenitrificans DSM 465^T and A. kamchatkensis subp. asaccharedens F81 were found to adhere mainly to rubber, polycarbonate, PTFE and stainless steel surfaces. In addition, the efficacy of sporicidal agents on the spores of these bacteria was investigated and only peracetic acid, cetylpyridinium chloride and formaldehyde were found to be the most effective of the sporicidal agents tested. Among the sporicidal agents that showed high efficacy against spores, peracetic acid and nitric acid were selected because they had the shortest contact time, low toxicity and cost. Binary combination effects were tested by determining the LD50 values of the selected agents and it was found that there was a synergistic effectbetween these two effective chemicals. In addition, the thermal resistance profiles of planktonic and sessile spores of A. flavithermus DSM 2641^T and G. thermodenitrificans DSM 465^T were evaluated.