Antibacterial effects of microencapsulated Lactobacillus plantarum cell free supernatant in combination with propolis extract against fish spoilage bacteria

In this study, in vitro effects of microencapsulated Lactobacillus plantarum cell free supernatant (LPS) in combinations with aqueous (PW) or ethanolic propolis (PE) extract (1%) against fish spoilage bacteria (E. cloacae, P. luteola, P. mirabilis and P. damselae) were investigated. According to the SEM analysis results, it was seen that the microencapsulated samples had a particle size of <19 µM. According to GC-MS results, the major components in microencapsulated LPS in combination PE extract were furyl alcohol (42.95%), 6,8-dibromo-2- (3-pyridyl) -4-phenyl -quinazoline (11.34%), acetic acid (8.10%) and 1-Penten-3-ol (8.03%). Microencapsulated LPS in combination with PW extract contained 2-furanmethanol (47.15%), maltol (13.09%), acetic acid (10.03%) and 2-ethyl-hexanal (9.15%) as the main component. Control and microencapsulated LPS effect against the P. mirabilis with an inhibition zone diameter of 8.33 and 8.00 mm, respectively. The LPS microencapsulation process showed similar MIC values on P. damselae and P. luteola as the control groups, whereas lower MIC values on P. mirabilis and E. faecalis. It has been observed that combinations of propolis extract, especially its aqueous extract, together with the microencapsulated L. plantarum supernatant can be potentially used as antimicrobials due to its rich bioactive substance content and high antimicrobial activity. Keywords: Lactic acid bacteria, cell-free supernatant, propolis, fish spoilage