Listeria monocytogenes biofilms on glass surface: survival and efficacy of two sanitizing agents for inactivation

Abstract

Listeria monocytogenes is a very important seafood-borne pathogen, which is capable of forming biofilm on different food-contact surfaces. The efficiency of two commonly used sanitizing agents of seafood-processing industry was checked for inactivation of this pathogen in biofilm formed on glass surface. Treatment with 220 ppm sodium hypochlorite for 5 min and 1000 ppm benzalkonium chloride for 30 seconds could totally inactivate the L. monocytogenes ATCC 19115 in the biofilm. Reduction of the level of this organism to a great extent was possible even at lower concentration in case of both the sanitizers. However, the planktonic cells were found to be highly susceptible. Treatment with 130 ppm sodium hypochlorite for 5 min or 100 ppm benzalkonium chloride for 30 seconds can totally inactivate planktonic cells of L. monocytogenes. During storage at 30 ºC, the L. monocytogenes could be recovered from the biofilm upto 26 days of storage. The concentration of chlorine (50-100 ppm), which is commonly used for disinfection different surfaces of seafood-processing plants, can reduce the level of this pathogen to a great extent. The findings of the present study will be helpful in designing proper guidelines for prevention of transmission of L. monocytogenes through seafood-processing plants.