Microorganisms and their biological products have been used as a biological control against many pathogenic. Streptomyces spp. are one of the microorganisms that can be deployed in the field as biological control of plant pathogenic fungi as an alternative to chemical pesticides.


In this study, one hundred twenty-four isolates of Streptomyces spp. from Syrian soils were in vitro screened for their ability to inhibit the growth of various barley pathogenic fungi: Cochliobolus sativus, Pyrenophora graminea, Fusarium verticillioides, and Fusarium solani.


Streptomyces isolates which showed the highest antagonism activity for each fungus were selected.


The inhibition rate of fungal growth by the selected strains ranged between 51 and 67%. The growth inhibition of the fungus F. solani was 51% when S. malachitofuscus Str69 strain was used, compared with 67% for C. sativus by the Str74 strain. The selected Streptomyces isolates showed their production of hydrolytic enzymes that had a role in the antagonistic activity against fungi, particularly the enzymes chitinase and glucanase. The cell-free supernatants effectively inhibited the growth of the fungi, where they reduced C. sativus, P. graminea, F. verticillioides, and F. solani by 57, 68, 19, and 30%, respectively.


The results of this study demonstrated that selected Streptomyces spp. isolates and their free cell crude extract could be used as a bio-control agent against the studied barley pathogenic fungi.

Keywords: Streptomyces , Antifungal activity, Cochliobolus sativus, Fusarium, Fungi, Enzymes.
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