Efficiency of Lactic Acid Bacteria as biological control agents against some Fungi

Abstract

In this study, Lactic Acid Bacteria (Lactobacillus fermentum , Lactobacillus reuteri , Lactobacillus sp. no.1, Lactobacillus sp.no.2 and Lactococcus sp.) were screened in vitro for antifungal activity against )Fusarium oxysporum , Phytophthora infestans , Pythium ultimum and Alternaria sp. (.The inhibition ratio was (100 %) on the MRS(Man, Rogosa, Sharpe) agar for all the LAB isolates against all fungi used at both 30 ºC and 37 ºC for 5 days . On the other side, all LAB had significantly high inhibition (P< 0.05) on PDA (Potato Dextrose Agar) medium at 37 ºC than that at 30 ºC for 5 days . The results of the Overlay assay showed that the five LAB used inhibit the growth of all fungi used by more than > 8 ٪ of plate area except by more than > 8 ٪ of plate area except L. fermentum inhibit Alternaria sp. by (3-8) % of the plate area and Lactococcus showed no visible inhibition against Fusarium oxysporum at 30C0 . The statistical analysis of antifungal activity of LAB cell-free supernatant showed significant differences (P<0.05) after 24 h against all fungi used. The LAB have shown that there were high significant inhibition (P<0.05) on MRS agar than on PDA agar. This study led to suggest that food-derived LAB strains could be selected for biotechnological application to control phytopathogenic fungi.