Isolation and screening of endophytic fungi from Eritrean traditional medicinal plant Terminalia brownii leaves for antimicrobial activity

Abstract

Plants formed the basis of sophisticated traditional medicine systems that have been in existence for thousands of years. But, the advent of drug resistance in human pathogenic bacteria and others has prompted a search for more and better antibiotics. This has led to the identification of a new promising source of antimicrobials known as endophytes. Hence, our study was aimed to investigate the ability of endophytic fungi isolated from T. brownii to produce secondary metabolites, which can act as antimicrobial agents. In this preliminary investigation, the leaves were used for isolation of endophytic fungi and fermented, and the cell free ferment broth was subjected to antimicrobial screening against six human pathogens; Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli and Candida albicans by using standard protocol of agar well diffusion method. The results of the endophyte isolation gave three fungal isolates named TBF1, TBF2 and TBF3. According to morphological and microscopical characterizations, the isolates were found to be similar to Rhizophus oryzae (TBF1), Aspergillus niger (TBF2) and Aspergillus flavus (TBF3). Two of the three isolated endophytes i.e., TBF2 and TBF3 showed potential antimicrobial activity against S. aureus and no inhibition was found against other tested pathogens. The present study has proven that T. brownii may be a rich source of endophytic fungi with antimicrobial potential and our findings may form a basis for further studies on endophytic fungi from medicinal plants for antimicrobial activities. Key words: Agar well diffusion method, antimicrobial activity, endophytic fungi, medicinal plant, Terminalia brownii