Antibiofilm activities of crude extract and supernatant of Actinobacteria against biofilm formed by foodborne pathogens and food spoilage bacteria

Bacteria form a biofilm that attaches the microbial population to a solid surface, thus acting as a barrier to protect external stresses from the bacterial community. In the food industry, biofilms are believed to be responsible for food-borne diseases and food spoilages. This research was conducted to characterize anti-quorum sensing (QS), anti-biofilm activity of crude extract, and supernatant from Actinobacteria isolates against biofilm of foodborne, and food spoilage bacteria. Actinobacteria is the group of filamentous spore-forming Gram-positive bacteria, which is well recognized as a source for novel secondary metabolites, such as anti-biofilm and anti-quorum sensing. Two isolates of Actinobacteria utilized in this study were recovered from the Indonesian marine environment in the previous study. Both isolates demonstrated anti-QS activity on early detection assay using the agar overlay method. The Actinobacteria isolates were fermented, and the crude extracts were obtained through extraction using 100 % ethyl acetate and further evaporation, while the supernatant was collected directly following fermentation. The entire Actinobacteria isolates displayed capability as an anti-biofilm agent in crude extracts form at a concentration of 20 mg.mL-1, alongside when in its supernatant form. The Actinobacteria isolates in both extracts and supernatants form demonstrated anti-QS activity based on the N-Hexanoyl-L- homoserine lactone (HHL) validation assay and were also categorized as non-toxic based on Brine Shrimp Lethality Assay (BSLA).