An antimicrobial compound from the endophytic fungus Phoma sp. isolated from the medicinal plant Taraxacum mongolicum

An endophytic fungus was isolated from the leaves of the Chinese medicinal plant Taraxacum mongolicum Hand.-Mazz. The phylogenetic and physiological characterization indicated that the isolate, strain PG23, was Phoma sp. Culture filtrate of PG23 displayed antagonism against some pathogenic bacteria owing to the existence of antibacterial compounds. The filtrate revealed in vitro strong antimicrobial activity on the studied bacteria, confirmed by the inhibition zone diameter (24 h after incubation) ranging from 24.2 to 40.0 mm depending on the microorganism being tested. The antibacterial extract was fractionated and purified on silica gel chromatography. From the culture extracts of PG23, a bioactive compound was isolated by bioactivity-guided fractionation and identified as 2-hydroxy-6-methylbenzoic acid based on spectral analysis obtained from nuclear magnetic resonance, infrared, and mass spectrometry. The results show that 2-hydroxy-6-methylbenzoic acid has potential for poultry and aquatic product disease control.

► The endophytic fungi Phoma sp. PG23 was isolated and identified from Taraxacum mongolicum ► The antimicrobial activities and preliminary acute toxicity of the culture filtrate of Phoma sp. PG23 were examined. ► One antimicrobial compound from culture filtrate of strain PG23 was isolated by HPLC and identified by NMR and GC–MS.