Abstract

This work was designed to identify and taxonomically classify Streptomyces strains isolated from the rhizospheres of various plant species; banana, rose, pomegranate and grape plants, having antagonistic activity against some microbial (bacteria and fungi) tissue culture contaminants. Streptomyces strains with the most potent antagonistic traits were identified using sequencing of 16S rRNA gene amplicons generated by PCR of DNA and blasting the sequences into GenBank. TheStreptomyces isolates had antagonism against five identified fungi (Aspergillus fumigates, Aspergillus flavus, Aspergillus nidulans (1), Aspergillus nidulans (2),Cladosporium herbarum) and against five out of the 11 Gram positive bacilli bacterial contaminants. The three selected Streptomyces isolates (14, 15 and 17) were identified as strains of Streptomyces noboritoensis, Streptomyces albolongus andStreptomyces griseorubiginosus, respectively. Isolate 14 for which 1443 nucleotides were obtained was compared with eight universal Streptomyces strains and was classified as a new species of gray Streptomyces, to be named Streptomycesnoboritoensis SSMA2-KSA strain. This study recommends conducting further studies on the use of streptomycetes in the biological control in a large scale production.

Key words: Taxonomy, Streptomyces, microbial tissue culture contaminants, antagonistic activities, 16S rRNA.