Abstract

The discovery of new metabolites potentially bioactive against pathogenic microorganisms, mainly multidrug resistant, has aroused interest in endophytic fungi. The plant-associated microorganisms have been an important source for development of new compounds of biotechnological interest. This study aimed to investigate the antibacterial capacity of the endophytic fungus, Phoma sp. URM 7221 isolated from the medicinal plant Schinus terebinthifolius against human-pathogenic bacteria. An endophyte was isolated from S. terebinthifolius leaves. Phoma herbarum URM7221 was characterized morphologically and on the basis of ITS rDNA sequence. Primary antimicrobial activity was evaluated using the agar diffusion method and fermentation in liquid medium. Six different solvents were used to extract the active metabolites from fungal biomass and metabolic liquid. An antimicrobial activity test from the extract was carried out using a disk diffusion method with the endophytic extract containing the best antibacterial activity. Two tests were performed: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Partially purified secondary metabolite extracts were analysed by thin layer chromatography (TLC). Liquid metabolically bioactive compounds extracted with petroleum ether revealed a MIC of 25 and 500 μg.mL⁻¹ against S. aureus and MRSA, respectively. Ether and methanol extracts were assessed by chemical analyses and contained phenolic compounds, triterpenes, steroids, reducing sugars, mono- and sesquiterpenes. The thin layer chromatography assay showed the activity of different antimicrobial compounds produced by Phoma sp. URM7221. This endophyte (URM7221) could be efficiently used for production of bioactive metabolites against pathogenic microorganisms, with significant biotechnological potential.

Key words: Bioactive compounds, endophytic fungi, pathogenic bacteria, multidrug-resistance, antibacterial agents.