Journal of Pure and Applied MicrobiologyVol. 4 No. 2

Biocontrol of Pseudomonas fluorescens and Bacillus subtilis Against Fungal Pathogens Isolated from Selected Infected Leaves

N. Uma Maheswari* and H. Umamageswari

P.G. and Research Department of Microbiology, Sengamala Thayaar Educational Trust Women’s College, Sundarakkottai, Mannargudi - 614 001, India.

Received on 25 March 2010 and accepted on 08 May 2010



The rhizosphere bacteria are ideal for used as biocontrol agents as they can provide the front line defense for plant against the attack by various plant pathogens. The test fungal pathogens were isolated from the infected leaf samples such as coconut, banana, and rice by using Potato dextrose agar medium. The antagonistic effect of bacteria against test pathogen was determined by dual culture technique. In this experiment Bacillus subtilis showed high inhibitory property on the selected infected leaves when compared with Pseudomonas fluorescens. The growth of test organism in the Potato dextrose agar medium treated with different concentration of culture filtrate of Bacillus subtilis and Pseudomonas fluorescens (5%, 10%, and 15%) were studied. The maximum percentage of inhibition of the growth of the test pathogens were at 15% culture filtrate of Bacillus subtilis (86.53%) and Pseudomonas fluorescens (78.88%). Bacillus subtilis culture filtrate contain maximum amount of protein content (50µg) than Pseudomonas fluorescens (35µg) was estimated by Lowry’s method.

Keywords : Biocontrol agents, Fungal pathogens, Dual culture technique, Antagonism, Inhibition.