Studies on Isolation, Classification and Phylogenetic Characterization of Novel Antifungal Streptomyces sp. VITSTK7 in India

M. Thenmozhi ； K. Kannabiran

《Current Research Journal of Biological Sciences》 2卷5期 (2010/09) Pp. 306-312

並列摘要

The aim of the study was to screen the antifungal activity of the crude extract prepared from the strain Streptomyces spp. VITSTK7 against Aspergillus sp. and to characterize the isolate. A total of 8 strains were isolated from the marine sediments collected at the Puducherry coast, India. All the eight strains were primarily screened for antifungal activity against three species of Aspergillus namely A. fumigatus, A. niger and A. flavus. Our search resulted in the isolation of a potential strain VITSTK7. The production media was optimized for maximum yield of secondary metabolites. The metabolites were extracted using ethyl acetate, lyophilized and screened for antifungal activity against the three Aspergillus species by well diffusion method. A maximum zone of inhibition (21 mm) was observed for A. fumigatus in comparison with the standard antifungal antibiotic Nystatin (20 mm). This potential strain was further identified based on Hideo Nonomura classification. A phylogenetic tree was constructed by maximum parsimony method to identify up to the species level. Molecular taxonomy and phylogeny revealed that the strain belonged to the genus Streptomyces and was designated as Streptomyces spp.VITSTK7. Blast search of the 16s rRNA sequence of the strain with the sequences available in the NCBI data bank showed a maximum similarity of 86% with Streptomyces longisporoflavus (DQ 442520) with the bootstrap value of 100. The 16s rRNA sequence of the strain Streptomyces spp.VITSTK7 was submitted to the GenBank under the accession number GQ 499369. The secondary structure of 16s rRNA and the restriction sites were also predicted using Genebee and NeBCutter online softwares, respectively.

並列關鍵字

Actinomycetes ； antifungal activity ； Aspergillus fumigatus ； Streptomyces spp. VITSTK7