Isolation and antifungal activity of methyl 2,3-dihydroxybenzoate from Paenibacillus elgii HOA73

The aim of the present study is to describe the purification and identification of methyl 2,3-dihydroxybenzoate (M2,3DB), isolated for the first time from Paenibacillus elgii HOA73, and to subsequently investigate its antifungal activity against important plant pathogens. The results show that M2,3DB can be purified by many different chromatographic techniques and is identified as methyl 2,3-dihydroxybenzoate based on nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) spectra analyses. M2,3DB was firstly evaluated for its antifungal activity, where the growth of Botrytis cinerea and Rhizoctonia solani was almost completely inhibited at an M2,3DB concentration of 50 μg/mL. Growth inhibition of Phytophthora capsici and Fusarium oxysporum f.sp lycopersici was found at the same M2,3DB concentration by 48.8% and 36.6%, respectively. Minimum inhibitory concentrations (MICs) of M2,3DB that inhibited any visible mycelial growth of B. cinerea, R. solani, and F. oxysporum f.sp lycopersici were defined as 32, 32, and 64 μg/mL, respectively. The broad antifungal activity of M2,3DB against various plant pathogens suggests its scope as a biofungicide in the management of plant disease.