Soil-borne pathogens like Macrophomina phaseolina pose a significant threat to black gram (Vigna mungo), a vital pulse crop in India. In this study, 21 rhizospheric bacterial isolates were initially screened, and 12 were characterized morphologically. Using the dual culture method, five isolates AC 2, AN 3, AF 4, JB 8, and NP 9 demonstrated strong antagonistic activity, with growth inhibition exceeding 50%, against M. phaseolina. These isolates underwent detailed morphological, biochemical, and molecular analyses, including 16S rDNA sequencing and ARDRA profiling. The isolates were identified as Bacillus licheniformis (AAU BCM 1), Bacillus stratosphericus (AAU BCM 2), Pseudomonas aeruginosa (AAU BCM 3), Pseudomonas azotoformans (AAU BCM 4), and Stenotrophomonas sp. (AAU BCM 5). Several of these antagonists produced key antifungal enzymes (lipase, protease, chitinase) and hydrocyanic acid (HCN), and some exhibited ACC deaminase activity, enhancing their potential as plant growth-promoting rhizobacteria. Scanning electron microscopy confirmed the antagonistic action of B. licheniformis against M. phaseolina hyphae. Antibiotic resistance profiling indicated strong survivability of the isolates in soil environments. These findings highlight the promise of native rhizospheric bacteria as sustainable biocontrol agents against M. phaseolina in black gram cultivation

Black gram, Macrophomina phaseolina, antagonistic rhizobacteria, ARDRA, 16S rDNA sequencing, Scanning electron microscopy, Dual culture assay

The study successfully identified and characterized five native rhizospheric bacterial isolates with potent antagonistic activity against Macrophomina phaseolina, the causal agent of root rot in black gram. Dual culture assays confirmed their efficacy, with growth inhibition nearing 70%. The isolates, identified through 16S rDNA sequencing and ARDRA, belong to diverse genera—Bacillus, Pseudomonas, and Stenotrophomonas. Their ability to produce antifungal enzymes, HCN, and ACC deaminase suggests a multifaceted mechanism of pathogen inhibition and stress alleviation in plants. The antibiotic resistance exhibited by these isolates may support their survival and colonization in the rhizosphere, enhancing their utility as biocontrol inoculants. The SEM images further corroborated the antagonistic interactions by showing physical damage to M. phaseolina hyphae. These findings underscore the potential of leveraging indigenous rhizobacteria for eco-friendly and effective disease management in black gram cultivation

Prajapati M.D., Puja Pandey, Yogeshvari K. Jhala, Hardik H. Patel and Hiren K. Patel (2025). Exploring Higher Root Rhizospheric Soil as a Source of Potential Bacterial Antagonist Against Root Rot Fungi Macrophomina phaseolina Infecting Black Gram. Biological Forum, 17(7): 116-127