Biosurfactant-mediated Biocontrol of Macrophomina phaseolina Causing Charcoal Rot in Vigna mungo by a Plant Growth Promoting Enterococcus sp. BS13

Abstract

A potential bacterial isolate Enterococcus sp. BS13 screened from rhizospheric soil of Vigna mungo was identified as Enterococcus sp. based on morphological, biochemical and genomic characterization. The biosurfactant producing activity of BS13 was based on many tests such as blood heamolysis test, CTAB agar, emulsification stability (E24) test, oil spreading/displacement assay, drop collapse assay, bacterial adhesion to hydrocarbons (BATH) assay and surface tension (ST) measurement after 72 h of growth. GC-MS and FT-IR analyses established the similarity of biosurfactant with glycolipid type biosurfactant. Furthermore, Enterococcus sp. BS13 displayed plant growth-promoting ability, HCN production and antagonistic activity against Macrophomina phaseolina. Scanning electron microscopic study of fungal mycelia from zone of inhibition showed hyphal degradation, halo cell formation and mycelial deformities in the pathogen. M. phaseolina sclerotia formation and development were arrested towards the zone of interaction; consequently, such mycelia and sclerotia lost the vigour. In pot trials Enterococcus sp. BS13 increased the growth of V. mungo with considerable diseases reduction. Hence, Enterococcus sp.BS13 bears ability of biosurfactant production, plant growth promotion and biocontrol of M. phaseolina. Therefore, the exogenous application of BS13 can be a potential strategy to accelerate plant growth promotion and biocontrol of M. phaseolina.