Effect of cell-free supernatant of Lactobacillus reuteri on the growth rate oftoxigenic Fusarium oxysporum in vitro

Lactobacillus reuteri is a probiotic bacteria thatproduces, a wide-range of antimicrobial substance, “reuterin” in the presence of glycerol. The present study was aimed to evaluate the efficacy of Lactobacillus reuteri against the growth of Fusarium oxysporum. So, the cell-free culture supernatant (CFCS) of Lactobacillus reuteri was prepared by centrifugation (8000 rpm for 15 min) of bacterial overnight culture, with and without 2% glycerol medium. Inhibition effects, evaluated by two methods micro-well dilution (both of CFCSs: two-fold dilution series (100, … 6.25 µl); 10 µl fungal spore suspension (2×106 spores/ml); PDB medium) and Tube culture (both of CFCSs: (80, 60 µl); 10 µl fungal spore suspension (2×106 spores/ml); SDB medium).The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of CFCS obtained from glycerol-medium, was determined as 60µl. The CFCS obtained from glycerol-free medium had no inhibitory effect on F.oxysprom growth. The results of the present study revealed that the CFCS of Lactobacillus reuteri obtained from medium with 2% glycerol, probably due to the presence of reuterin, is able to inhibit the growth of toxigenic Fusarium oxysporum and can be used in the feed and food industry as a potential bio-controller against toxigenic Fusarium species.