Abstract

Isoken H. Ogunmwonyi, Ntsikelelo Mazomba, Leonard Mabinya, Elvis Ngwenya, Ezekiel Green, David A. Akinpelu, Ademola O. Olaniran, Kim Bernard and Anthony I. Okoh*

A total of 84 culturable marine actinomycetes belonging to 15 generic morphotypes were isolated from water and rock scrapings from the Nahoon beach, a coastal shore of Indian Ocean in the Eastern Cape Province of South Africa. The colonies showed diverse morphological characteristics and their occurrence and distribution varied with sample type. The rock scrappings yielded more actinomycetes morphotypes than the water samples. Streptomyces was most prevalent in both samples. Actinoplane, Actinosynnema, Norcadia, Norcardiopsis, Streptosporagium and Intrasporagium were present in rock scrapings but absent in water samples. Kibdellosporium was present in water sample and absent in rock scrapings. The Streptomyces isolates were selected and preliminarily screened for antimicrobial activity. The bioactive compounds of 10 most potent Streptomyces isolate was extracted twice with equal volume of ethyl acetate (1:1 v/v). The ethyl acetate extracts of the putative Streptomyces isolates showed activities against at least 6 and up to 26 of the 32 test bacteria screened. Inhibition zones were found to range between 9 and 32 mm diameters at a concentration of 10 mg/ml. The partial characterization of the crude extracts by IR spectra analysis revealed the possible presence of terpenoid, long chain fatty acids and secondary amine derivatives compounds in the extracts. We conclude that the Nahoon beach promises to be a veritable resource for diverse marine actinomycetes of potentials for bioactive compounds production and novel drug discovery.