Anti-biofilm mechanism of Malaysian natural clay against food-borne Staphylococcus aureus and Salmonella Typhimurium

Abstract

Natural clay is useful for cleaning the environment due to its antibacterial properties. Malaysian natural clay of Kuala Gula was investigated for its anti-biofilm activity against single biofilm formation of Staphylococcus aureus and Salmonella Typhimurium. Clay suspension (50.0 %) reduced S. aureus biofilms by 4.4 log at 24 h, respectively, while it reduced (25.0 and 12.5 %) by a 4.2 and 3.91 log reduction, respectively, at 6 h. Despite being less effective, clay leachate (50.0 %) was effective in removing Salmonella Typhimurium biofilm with a decrease of > 3 log in 24 h. An anti-biofilm mechanism was conducted by imaging microbial morphology using SEM, which revealed abnormalities, including ruptured cell walls, after exposure to Kuala Gula clay and supported by CLSM images. Additionally, the anti-biofilm activity was associated with Reactive Oxygen Species (ROS) production. The present study reveals that Malaysian clay has potential as a natural anti-biofilm agent in the food industry.