Biofilm Forming Ability of Listeria Monocytogenes and Staphylococcus Spp. on Polypropylene Surface and the Inactivation by using Homemade Sanitizer

Yap, Bee Shin (2019) Biofilm Forming Ability of Listeria Monocytogenes and Staphylococcus Spp. on Polypropylene Surface and the Inactivation by using Homemade Sanitizer. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Listeria monocytogenes is a Gram positive foodborne pathogen that responsible for listeriosis. It can be transmitted through accidental consumption of foods that are contaminated by the pathogens. One of the objectives of the study is to compare biofilm forming ability of mono-species L. monocytogenes and mixed-species of L. monocytogenes and Staphylococcus spp. over time. The food contact surface used is polypropylene coupons with 2 cm × 2 cm × 0.8 cm each. Three treatments were applied in this study. Treatment 1 focused on uncontaminated surface while Treatment 2 focused on contaminated surface with the presence of chicken residues, both treatments allowed formation of mono-species biofilms of L. monocytogenes. The results showed that the presence of chicken residue on the polypropylene surface has relatively slight effect on biofilm formation since most of the heat-sensitive nutrients have undergone thermal decomposition during preparation. For Treatment 3, mixed-species biofilms of L. monocytogenes and Staphylococcus spp. were developed on contaminated surface with the presence of chicken residues. Co-cultivation of L. monocytogenes with Staphylococcus spp. does not have much effect on the formation of total number of mixed-species biofilms. Overall, both mono- and mixed-species biofilms exhibit an increase in biofilm forming ability as the incubation period increases from 1, 3, 5, 7, 26, 73 to 168 h. Besides, this study is also aimed to compare the efficiency of homemade and commercial sanitizer in removing biofilm communities that adhered on the polypropylene surface. Sanitization was carried out at 26 and 168 h by using commercial and homemade sanitizers with 25%, 50% and 100% concentrations each for all three treatments. The results indicated that homemade sanitizer has almost similar level of efficiency with commercial sanitizer (P > 0.05) regardless of concentrations and treatments applied. However, biofilms tend to develop resistance to antimicrobial agent as the incubation time lengthened in which sanitizer treatments are less ineffective to remove the adhered biofilms from a contact surface. Keywords: mono-species biofilm, mixed-species biofilm, biofilm forming ability, Listeria monocytogenes, Staphylococcus spp., homemade sanitizer, commercial sanitizer