Inhibitory activity of Co-microencapsulation of cell free supernatant from Lactobacillus plantarum with propolis extracts towards fish spoilage bacteria

Abstract

Antibacterial properties of microencapsulated Lactobacillus plantarum cell-free supernatant (CFS) in combinations with aqueous or ethanolic propolis extract at doses of 1% against fish spoilage bacteria were investigated. Microencapsulated samples contained more than 17 compounds, of which furyl alcohol, acetic acid, maltol, and 2(5H) furanon were identified as common compounds. The effects of microencapsulated CFS from L. plantarum in combination with or without propolis extracts on the fish spoilage bacteria varied according to the bacterial species. Among the fish spoilage bacteria, the highest antimicrobial activity of samples was observed against P. damselae with >15.5 mm inhibition diameter zone. Pure and microencapsulated CFS from L. plantarum showed the lowest antimicrobial effects on P. mirabilis with a corresponding inhibition diameter zone of 8.33 and 8.00 mm. Microencapsulated CFS from L. plantarum in combination with aqueous propolis extract had 25 mg/ml of MIC and 50 mg/ml of MBC on all bacteria although the bactericidal effect of microencapsulated samples in combination with ethanolic propolis extract occurred at a level of above 50 mg/ml. The study results revealed that co-microencapsulation of CFS obtained from L. plantarum with propolis extract, especially its aqueous extract, could be potentially used as antimicrobial agents to overcome microbial growth in foods.