Screening of Soil Isolates of Bacteria for Antagonistic Activity against Plant Pathogenic Fungi

Abstract

The most common approach to biological control comprised of selecting antagonistic microorganisms, studying their modes of action and establishing a biological control product. The present study was an attempt to screening of soil isolates of bacteria for antagonistic activity against plant pathogenic fungi. Bacterial isolates from soil samples were identified by cultural, morphological and biochemical characterisation. Bacterial isolates were then screened for their antagonistic activities against the tested plant pathogenic fungi. A total of 14 isolates belonging to 4 different species of bacteria with inhibitory activity against selected fungi were isolated from soil samples and identified biochemically. They were recognised in the genera Bacillus (B. subtilis, and B. amyloliquefaciens), Klebsila spp. and Micrococcus spp. The effect of the antagonistic activity of Klebsila sp, Bacillus sp and Micrococcus sp against plant pathogenic fungi was checked. The average diameter of inhibition zone (cm) of bacterial isolates against plant pathogenic fungi Penicillium purpurogenum was recorded as Klebsila spp. 2cm, Bacillus subtilis 2.6cm, B. amyloliquefaciens 0.866cm and Micrococcus spp. 1.6cm. With respect to the considerable tolerance of B. subtilis to environmental stresses and their facile production by current fermentation technology, bacterial isolates identified in this study with a diverse range of antifungal activities can be known as prospective resources of novel naturally occurring antifungal agents for controlling pathogenic fungi in medicine and agriculture. Biological control practices require an integrative approach, and more knowledge than chemical control.