Isolation and characterization of antagonistic activity of some streptomycetes and their specific actinophages from soil

Abstract

Background and Objective: Phages specific to actinomycetes are common, active in the soil and gladly detected. Soil streptomycetes are having antibiosis activities against numerous bacteria, fungi and plant viruses. Thus, this study was designed to isolate, purify and characterize some streptomycetes active against some microorganisms from soil followed by isolation of their specific phages. Materials and Methods: Antagonistic activities of these streptomycetes isolates were tested against Bacillus subtilis, Pseudomona sp., Serratia sp. and Aspergillus niger. To confirm their biological characterization of the streptomycetes isolates under investigation, the 16SrRNA gene was also used. The presence of specific lysate actinophages in the soil samples were tested by spot test technique and then propagated and purified for further characterization. The morphology of the purified actinophages was determined by electron microscopy. Results: The five selected Streptomyces isolates having effective antagonistic activity were biologically and molecularly identified as Streptomyces sclerogranulatus (QQ06), Streptomyces mutabilis (QQ07), Streptomyces heilongjiangensis (QQ08), Streptomyces sparsus (QQ09) and Streptomyces purpurascens (QQ10) strains. Electron micrographs showed the presence of filamentous virus-like particles with lengths of 21.4×928.57, 25×750, 21.4×857.14, 21.4×885.7 and 21.4×857.14 nm specific to Streptomyces strains QQ06, QQ07, QQ08, QQ09 and QQ10, respectively and belong to the family Inoviridae. Conclusion: Phage of Inoviridae was considered as the first time against streptomycetes isolates, therefore, additional and advanced studies should be carried out at the level of molecular characterization.