Antimicrobial activity of crude extract of endophytic fungi isolated from leaves of Kigelia africana and Phyllanthus niruri collected from Dar es Salaam Tanzania

Effectiveness of endophytes crude extract against pathogens

Abstract

One of the main challenges that hinder achievement of the third millennium sustainable development goal is emergence of infectious agents that are resistant to existing antimicrobials. These challenges entails search for novel bioactive compounds like exploring untapped potential of medicinal plants and their associated endophytes. The present study was aimed to investigate the antimicrobial activities of crude extracts of endophytic fungi isolated from medicinal plants Kigelia africana and Phyllanthus niruri. Pure isolates of endophytic fungi were subjected to initial screening, and isolates that exhibited inhibition were genotyped by Sanger sequencing for genus and species confirmation. Then, antimicrobial activity of crude extracts of selected isolates: Nigrospora sphaerica, Meyerozyma guilliermondii, Alternaria alternata and Phyllosticta capitalensis was evaluated by disc diffusion method against E. coli (Gram-negative), S. typhi (Gram-negative), and S. aureus (Gram-positive). Findings indicated high variability (8.5 -23.1 mm) of crude extract concentrations of isolates, and the highest zone of inhibition was found in ethyl acetate crude extract of M. guilliermondii against S. aureus. Furthermore, the lowest MIC (9.9 >MIC>5.0) was found in n-hexane crude extract of P.capitalensis against S. typhi. However, all crude extracts did not show any activity against E. coli. Results of present study corroborate on the influence of extracting solvent on the effectiveness of crude extract of isolates against pathogen microorganisms. Interestingly, findings demonstrated the potential of endophytes from medicinal plants for medical applications, and therefore further investigation may lead to discovery of novel bioactive compound potent to resistant infectious agents.