Isolation and characterization of metabolites from Bacillus licheniformis MH48 with antifungal activity against plant pathogens

- Firstly, isolation of benzoic acid from Bacillus licheniformis MH48.
- As the concentration of bacterial culture filtrate (BCF) increased, the inhibition rate of plant pathogens increased.
- Benzoic acid showed minimum inhibitory concentration of 128 μg/mL against R. solani and C. gloeosporides.

In this study, we isolated Bacillus licheniformis MH48 from rhizosphere soil and demonstrated that this strain shows significant antifungal activity against Rhizoctonia solani, Colletotrichum gloeosporioides, and Phytophthora capsici. Our results showed that a 50% concentration of bacterial cell-free culture filtrate of B. licheniformis MH48 shows strong activity against fungal pathogens. Benzoic acid produced by B. licheniformis MH48 was purified by various chromatographic techniques and identified by nuclear magnetic resonance and gas chromatography-mass spectrometry analysis. Benzoic acid displayed antifungal activity against R. solani and C. gloeosporides with minimum inhibitory concentration of 128 μg/mL against mycelial growth. Microscopic examination revealed that benzoic acid (50 μg/mL and 100 μg/mL) transformed C. gloeosporioides conidial morphology and inhibited conidial germination. In addition, benzoic acid (100 μg/mL and 200 μg/mL) degraded R. solani mycelia. Therefore, our results demonstrate that B. licheniformis MH48 strain shows potential for utility as a biological agent for the control of various fungal pathogens of plants.