Title: Identification and Antibiosis of a Novel Actinomycete Strain RAF-11 Isolated From Iraqi Soil.
Abstract: A total of 35 actinomycetes strains were isolated from and around Baghdad, Iraq, at a depth of 5-10 m, by serial dilution agar plating method. Nineteen out of them showed noticeable antimicrobial activities against at least, to one of the target pathogens. Five among the nineteen were active against both Gram positive and Gram negative bacteria, yeasts and moulds. The most active isolate, strain RAF-11, based on its largest zone of inhibition and strong antifungal activity, especially against Candida albicans and Aspergillus niger , the causative of candidiasis and aspergillosis respectively, was selected for identification. Morphological and chemical studies indicated that this isolate belongs to the genus Streptomyces . Analysis of the 16S rDNA sequence showed a high similarity, 98 %, with the most closely related species, Streptomyces labedae NBRC 15864T/AB184704, S. erythrogriseus LMG 19406T/AJ781328, S. griseoincarnatus LMG 19316T/AJ781321 and S. variabilis NBRC 12825T/AB184884, having the closest match. From the taxonomic features, strain RAF-11 matched with S. labedae , in the morphological, physiological and biochemical characters, however it showed significant differences in morphological characteristics with this nearest species, S. labedae, which encourage us to consider our starin as a novel isolate and was given the suggested name, Streptomyces labedae strain RAF-11. ISP-4 broth medium supplemented with glucose and soybean powder at concentrations of 1g % and 0.1g % as carbon and nitrogen sources respectively, for 120h incubation at 28 °C, increased the active compounds production, where we recorded a strong activity against yeasts, 42mm inhibition zone against Candida albicans , 41mm against C. pseudotropicalis , 40mm against C. tropicalis , followed by 38mm against Rhodotorula minota and Aspergillus niger then, 35mm against both Aspergillus flavus and Bacillus subtilis. N-butanol was best solvent for antibiotic extraction compared to the other tried solvents.
Publication Year: 2013
Publication Date: 2013-11-24
Language: en
Type: article
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Cited By Count: 1
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