Biocontrol potential of Lactobacillus strains isolated from corn silages against some plant pathogenic fungi

The objective of the present study was to isolate and characterize effective lactic acid bacteria (LAB) with antifungal activities from some corn silages in Iran. The corn biomass was harvested from fields of three different regions, chopped, and ensiled in the lab silos. From 200 LABs isolates, 18 isolates with the highest acidic pH resistance (up to pH 3), salt resistance (up to 8%) and growth at 15-45 degrees C were selected for the next experiments. The highest (11.31 mg/ml) and the lowest (1.9 mg/ml) lactic acid production among the selected strains were belonged to the isolates E4 and G1, respectively. The antifungal properties of the selected strains were evaluated against some important plant pathogenic fungi, including Fusarium verticillioides, Penicillium sp. and Verticillium dahlia, and also against a parasitic oomycote "Pythium aphani dematum". The in vitro experiments confirmed that the strains could inhibit from 0 to 40 mm of mycelial growth of different fungi. Based on amplification and sequencing of the16SrDNA gene, the strains were belonged to Lactobacillus fermentum (61.2%), L. plantarum (11.2%), L. paralimentaris (11.2%), L. pentosus (5.6%), L. buchneri (5.6%), and Sporolactobacillus (5.6%). The field experiments confirmed that different combinations of the selected strains could reduce disease index F. verticillioides up to 40%. This is the first report of antifungal activity of lactobacilli strains against F. verticillioides at lab and field levels. Finally, it could be concluded that the native LABs isolated form Iranian corn silages have high antifungal activities and via their biochemical activities may be used as silage additive to enhance quality and durability for ensiled corns.