Evaluation of Secondary Metabolites of Some Fungi Isolated From Beach Soils of Lagos, Nigeria Against Some Pathogens

Abstract

Three beach soils in Lagos, Nigeria were screened for the presence of antibiotic producing fungi against 8 test pathogenic bacteria & fungi. The physiochemical parameters of the soils were determined following standard procedures. Soil plate dilution method was employed for isolation of marine fungi and they were identified based on cultural and microscopic characteristics. Primary screening of isolated fungi for antibiotic potential was determined by perpendicular streak method against known pathogenic test organisms (Escherichia coli, Saphylococcus aureus, Klebsiella pnuemoniae, Pseudomonas aeruginosa, Candida albicans, Saccharomyces cerevisiae,Aspergillus niger and Aspergillus fumigatus). Further sreening of the product of secondary metabolism [antibiotic] of the active fungi was done by agar disc diffusion assay. The fungus with the highest secondary activity was subjected to molecular analysis for further identification. pH of beach soils was alkaline ranging from 7.6-8.0, while temperature and moisture were normal ranging from 26.333 ± 1.155^a-30.333 ± 0.577^aand 7.142 ± 1.497^a-10.030 ± 3.130^a respectively. A total of four fungal species of 2 different genera were isolated from the beaches ;Aspergillus niger,Aspergillus flavus,Penicillium purpurogenum and Penicillium islandicum. Both primary and secondary assays revealed only antibacterial activities against Staphylococcus aureus and Psedomonas aeruginosa with no effect on all test fungi. Highest antibacterial activity[28+0.2^a] was exhibited by the fungus identified as Penicillium purpurogenum. Fungi from beaches in Lagos, Nigeria may be a promising source of antibacterial agent useful in the treatment of infections caused by S. aureus and P. aeruginosa.