Biological control of Aspergillus niger and Aspergillus flavus isolated fromstrawberry (Fragaria x ananassa Duch ) by streptomyces sp.

Actinobacteria are major producers of antifungal metabolites especially for use in agriculture biocontrol. In this study,the identification of Streptomyces sp. isolated from saline soil was carried out using morphological and biochemicalstudies. Optimization the culture conditions to produce metabolite was done. Two fungal samples were isolated fromdecaying strawberry. Their molecular identity was determined. Effects of Antifungal activity of Streptomyces sp.activities was determined by agar dilution method and inhibitory percentage of growth evaluated. Results showed thestrain of actinomyces isolate, strongly belongs to the genus Streptomyces. The highest metabolite wieght (۱.۴ gram)at ۳۲ ۰C, at pH ۶.۰, an incubation time of ۱۲۰h under aerobic conditions with culture medium compounds (yeastextract ۰.۴%, Dextrose ۰.۴ %, Pepton ۰.۵%, NaCl ۰.۵%) happened. Bioactive metabolite Streptomyces sp. effectedon two isolates of Aspergilllus (A. niger and A. flavus) isolate. Concentration of ۶ mg / ml of metbolites has ۱۰۰%growth inhibition, In contrast, mancozeb fungicide had ۱۰۰% growth inhibition at the same concentration too.Therefore, based on the results achived, metabolite produced by Streptomyces sp. can be used as a biological agent tocontrol the fungi infecting strawberr y and it is a suitable alternative to chemical fungicides.

Keywords:

Aspergillus , Biological fungicides , Streptomyces , strawberry