Factors Affecting Adhesion of Staphylococcus epidermidis to Stainless Steel Surface

In the food industry, microbial adhesion to equipment surfaces and subsequent development of biofilm are very serious issues because of potential to cause cross-contamination, which leads to lowered shelf-life, food spoilage, and transmission of disease [1-4]. Adhesion and subsequent growth on surfaces is a common strategy of bacteria for survival in both natural habitats and man-made environments [5]. Upon adhesion, bacterial cells could become less susceptible to cleaning and sanitizing agents, particularly after they have developed mature biofilm structure, wherein the matrix of organic polymers could provide additional protection. Reduced efficacy has been reported for a number of sanitation procedures against attached microorganisms [6]. Schwach and Zottola [7] showed that Pseudomonas fragi, Salmonella montevidio, and Bacillus cereus on stainless steel surface were not completely inactivated by treating with up to 150 ppm sodium hypochlorite. Stone and Zottola [8] demonstrated that P. fragi cells were not completely removed from stainless steel tube surface through a CIP cycle including alkaline (potassium hydroxide/potassium hypochlorite) and acid (phosphoric and citric acids) treatments. Listeria monocytogenes cells adherent to glass surface exhibited increased resistance to benzalkonium chloride, anionic acid sanitizer, and heat [9]. Therefore, to control the risk of microbial cross-contamination, further knowledge on the adhesion of microorganisms to abiotic surfaces is desired. Microbial adhesion to an abiotic surface is probably governed by complex interactions between the microorganism and the substrate surface involving physical, chemical, and biochemical factors. Several studies have been conducted on microbial adhesion onto dif ferent types of food contact surface [10-12]. However, the effects of factors on microbial adhesion have not yet been fully clarified or sometimes have been reported with inconsistency. For example, a milk-fouled stainless steel surface was reported to attract far more bacterial cells than a clean stainless steel surface [13], whereas adhesion of microorganisms suspended in milk to stainless steel surface was reported to be less than those suspended in phosphate buffered saline [14]. Opposing results have been reported also for the effect of roughness of stainless steel surface on microbial adhesion: positive correlation and independence between microbial adhesion and surFactors Affecting Adhesion of Staphylococcus epidermidis to Stainless Steel Surface