Bio-efficiency of Antifungal Lactic Acid Bacterial Isolates for Pomegranate Fruit Rot Management

Abstract

Out of 360 lactic acid bacteria (LAB) from leaves, flowers, buds and fruits of pomegranate, 224 were antagonistic towards Aspergillus flavus. In all, 81.6% of antifungal LAB were cocci and 18.3% were rod shaped. Majority (39.7%) of them was obtained from flowers and 27 isolates showed strong antifungal activity. Antifungal isolates were identified by Gram positive card kit and 16S rRNA gene sequencing as Enterococcus faecium, E. durans, Lactococcus lactis spp. cremoris, L. lactis spp. lactis, Leuconostoc mesenteroides, Lactobacillus brevis and Pediococcus pentosaceus. All the isolates showed maximum antifungal activity at pH 6.5 and 30 °C on MRS agar. The antifungal activity of cell free supernatants from the entire isolates was same under static and shaking conditions except PFL9 that showed decreased production under shaking conditions. The isolates, PFL4, PFL9, PB6, PB119, PL14, PFR61 and PFR77 showed broad antifungal activity. PFL9 and PFR77 had the longest survival on fruits and there was no significant reduction (P > 0.05) in their population till 8th day post inoculation as determined under field conditions. Cell formulations of PFL9 and PFR77, and Dithane (fungicide preparation) delayed the development of rot caused by Alternaria alternata, Phomopsis varsoniana and Corynespora cassiicola with equivalent potential (P > 0.05). Thus, pomegranate is the source of diverse antifungal LAB which can be used as an effectual biocontrol agent in the management of fungal fruit rot of pomegranate.