ANTIMICROBIAL ACTIVITIES OF STREPTOMYCES SPECIES ISOLATED FROM VARIOUS SOIL SAMPLES IN FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE(FUTA) ENVIRONMENT

Abstract

Streptomyces species were isolated from different soil habitats namely sandy, clayey, loamy, soil from household waste dumping sites, plantain cultivated land, vegetative land and ploughed land using pour plate method. The Streptomyces species isolated included Streptomyces albus from vegetative soil, S. viridoflavus and S.citreus obtained from household waste dumping site, S. flavovirens from loamy soil and S. antibioticus from plantain cultivated land. The pathogenic organisms against which these Streptomyces species were tested for antagonistic effects were bacteria which included Staphylococcus aureus, Bacillus subtilis, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 3883, Salmonella typhi, and fungi which included Aspergillus niger, Candida albican ATCC 10231, Microsporum canis, Tricophyton metagrophyte and Aspergillus flavus. Typed cultures were collected from Federal Institute of Industrial Research, Oshodi (FIIRO) while the clinical isolates were collected from State Specialist Hospital, Akure and Ekiti State Teaching Hospital, Ado Ekiti. Antagonistic test was carried out using Streptomyces species against the test organisms and the result revealed that S. albus from vegetative soil showed antagonistic effect against all the test pathogens except A. niger and M. canis. S. antibioticus and S. citreus had no antagonistic effect against all the test fungi. Streptomyces albus showed the best antimicrobial activities and was therefore selected for further characterization and purification. The active metabolite from S. albus was extracted using chloroform. Purification of the extract was performed using column chromatographic technique. The purified metabolite was again tested against the selected organisms. Results showed that the metabolite inhibited all the test bacteria with zones of inhibition against S.aureus and B. subtilis as 29.67mm and 28.00 mm respectively. T. metagrophyte showed the highest zone of inhibition (27.00mm). The active fraction showed higher zones of inhibition against S. aureus and E. coli (ATCC 25922) (29.67mm and 27.00mm respectively) in comparison with commercially produced chloramphenicol, streptomycin and tetracycline which showed 24.33mm and 26.00mm, 22.33mm and 27.67mm, 26.00mm and 18.00mm mean zones of inhibition respectively. The antifungal property of the metabolite was investigated against A. niger, C. albicans, M. canis, T. metagrophyte and A. flavus in comparison with commercially produced Nystatin, Ketoconazole and Griseofulvin. Result showed higher potency against T. metagrophyte as against the commercial antifungals (27.00mm). Infra-Red spectroscopy carried out on the active fraction revealed four important functional groups which are hydroxyl, carbon-hydrogen, carbonyl and aromatic groups. The nucleotide sequence of the 16S RNA showed 83% identity with Streptomyces albus. From the taxonomic feature, the Streptomyces isolate DSM 40313 matched with S. albus in the morphological, physiological and biochemical characters. Thus, it was assigned the name Streptomyces albus DSM 40313