Evaluation de l’activité antimicrobienne des champignons endophytes isolés des algues marines du littoral de Mostaganem

Abstract

In front of the rise in infections caused by multi-resistant bacteria, marine endophytic fungi are emerging as a promising source of new antimicrobial molecules. The aim of this work is to explore the antimicrobial potential of endophytic fungi isolated from marine macroalgae collected from the coasts of Mostaganem (Algeria). Macroalgae were collected manually from three beaches (Sidi El Madjdoub, Salamandre, Sablette). Endophytic fungi were isolated by culture on PDA medium, then purified and identified with macroscopic and microscopic criteria. Their antimicrobial activity was first screened against six pathogenic microbial strains by an antagonism test and an agar plug diffusion assay, followed by fermentation in liquid medium, extraction of secondary metabolites with ethyl acetate, evaluation of the antimicrobial activity of extracts by the agar disk diffusion method and determination of Minimum inhibitory concentration (MIC) and Minimum Bactericidal concentration (MBC). From eleven algal species tested, six enabled the isolation of endophytic fungi. Macroscopic and microscopic analysis of ten purified endophytic isolates identified species belonging to Penicillium and Aspergillus. Four fungal isolates (UR1, UR3, CR2, AL6.1) showed significant antimicrobial activity. Extracts from isolates CR2 and UR3 showed important antimicrobial activity against all the microbial strains tested, with zones of inhibition reaching 11.23 and 11.56 mm, respectively. The results confirm that some endophytic fungi associated with marine algae can produce bioactive metabolites with interesting antimicrobial properties.