Document Type : Pest Management
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Abstract
270 actinomycetes were isolated from soils of various regions of Iran including Khuzestan, Esfahan, Gilan, Hormozgan, Mazandaran, Tehran and Azarbayejane Gharbi provinces using special media. Inhibition effects of their extracellular broth were assessed against Fusarium oxyosporum, Aspergillus niger, Alternaria alternata by top agar layer method. 28 isolates showed antifungal activity against at least one of the fungi tested with more than 20mm diameter of inhibition zone and 5 isolates had more than 30mm diameter of inhibition zone. Isolate #35 demonstrated 10%-42% growth inhibition against all of the fungi tested and selected for further investigations. The effect of 3 seeding and 5 fermentation media on production of antifungal compound by this strain was assessed by cylinder diffusion assay method. The results showed that culture filtrate obtained from seeding medium 2 and Hicky-Tresner fermentation medium had maximum inhibition activity against three tested fungi. So, these media are proposed as suitable media for growth of the strain (inoculum preparation) and production of antifungal agent, respectively. Studies on molecular, morphological and biochemical characteristic of this isolate and 16S rDNA gene nucleotide analysis showed that isolate #35 had maximum similarity to Streptomyces cuspidosporusDSM41425. But significant differences in morphological and biochemical characteristics between this species and isolate #35 showed that further investigations are needed for determination of its species
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