Antifungal activity of Bacillus subtilis isolated from soil in Tehran's parks against Fusarium graminearum

Soil microorganisms play an important role in the biological control of pathogenic fungi. The aim of this investigation was to isolate soil-borne Bacillus subtilis with the ability to produce antifngal lipopeptides  that are suitable  for suppressing Fusarium graminearum, which contaminates wheat, corn, potato and a wide range of plants.Materials &

B. subtilis was isolated from the rhizospher of healthy plants of park slocated in the five areas north, south, east, west and center of Tehran and was identified based on morphological characteristics, biochemical tests and sequencing of 16S rRNA. The antagonistic activity of isolated strains against F. graminearum was investigated by Well method. The strains that inhibited the growth of fungi and showed the greatest inhibition zone, were selected. Surfactin of selected bacteria was purified by methanol method and bacterial metabolites and pure surfactin (Sigma Company) were compared with, high performance liquid chromatography (HPLC).

Among 60 isolated strains, 27 strains had antifungal activity. Six strains with the highest fungal inhibition zone (8-16 mm) were selected and their yellow color and transparency was a confirmation to HPLC. Two bacteria with the highest amount of surfactin production by  molecular method showed high similarity with B. subtilis.

The results show that Bacillus subtilis isolated from soil are good candidates for biological control of plant pathogenic fungi and therefore can a suitable alternative to chemical fungicides.