Evaluating Efficacy of Biosurfactants from Bacterial Isolates in Conferring Protection against Rhizoctonia and Sclerotium Infection in Wheat and Peanut Plants

Abstract

Aims: To isolate biosurfactant producers from natural habitat and to test the antimicrobial activity of the extracted biosurfactant against fungal plant pathogens. Study Design: The present study was designed to achieve the following objectives: 1. Isolation, screening and identification of potent biosurfactant producers. 2. Production, Extraction and Characterization of biosurfactant. 3. Testing the antimicrobial activity of the biosurfactant in vitro. 4. In vivo evaluation of the ability of biosurfactant to protect plants from fungal diseases. Place and Duration of Study: Department of Microbiology, Sophia College, University of Mumbai, Maharashtra, India, between June 2014 and May 2015.  Methodology: The bacterial isolates obtained from natural habitat were screened for biosurfactant producers using hemolytic plate assay, drop collapse test, penetration assay and emulsification activity. Potent biosurfactant producing isolates were biochemically characterized and identified up to genus level using Bergey’s manual. Biosurfactant was extracted by chloroform: Methanol method. Characterization of extracted biosurfactant was done using blue agar plate and orcinol assay. Agar well diffusion method was used to test antimicrobial activity of biosurfactants. Ability of the biosurfactants to provide protection against fungal plant pathogens was demonstrated in vivo using wheat and peanut plant seedlings. Results: Three isolates BMW1, BMW2 and BPS1 showing good biosurfactant activity were selected for biosurfactant production. They belonged to genus Pseudomonas, Bacillus and Micrococcus. Extraction of culture supernatant gave white residue which was used in further studies as biosurfactant. The biosurfactant produced by isolates BMW1 and BPS1 was glycolipid anionic biosurfactant while CTAB medium indicated non-ionic nature of biosurfactant from BMW2. Biosurfactant extracted from all three isolates showed good antimicrobial activity. Biosurfactant produced by BMW1 and BPS1 most effectively protected peanut plantlets from Sclerotium rolfsii infection and wheat plantlets from Rhizoctonia solaniinfection respectively. Conclusion: Our study suggested a strategy for eliminating plant pathogenic fungi by using microbial biosurfactants.