Isolation, purification and characterization of an antifungal molecule produced by Bacillus licheniformis BC98, and its effect on phytopathogen Magnaporthe grisea

• Published in: Journal of applied microbiology 2007-12, Vol.103 (6), p.2331-2339
• Main Authors: Tendulkar, S.R, Saikumari, Y.K, Patel, V, Raghotama, S, Munshi, T.K, Balaram, P, Chattoo, B.B
• Format: Article
• Language: English
• Subjects: antagonist; antagonists; Antibiosis - physiology; Antifungal Agents - isolation & purification; Antifungal Agents - metabolism; Antifungal Agents - pharmacology; Bacillus - genetics; Bacillus - metabolism; Bacillus licheniformis; Bacillus licheniformis BC98; Base Sequence; Biological and medical sciences; Chromatography, High Pressure Liquid - methods; Curvularia lunata; Fundamental and applied biological sciences. Psychology; lipopeptide; Magnaporthe - drug effects; Magnaporthe - physiology; Magnaporthe grisea; Magnetic Resonance Spectroscopy; Microbiology; Microscopy, Electron; Molecular Sequence Data; Oryza - microbiology; Oryza sativa; Plant Diseases - microbiology; Rhizoctonia bataticola; Soil Microbiology; surfactin
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2007.03501.x

Isolation of bacterial antagonist for use in the biological control of phytopathogenic fungi like rice blast fungus, Magnaporthe grisea, and to further purify and characterize the antifungal molecule produced by the antagonist. Bacterial antagonist exhibiting highest antifungal activity against the rice blast fungus M. grisea was isolated from soil and identified as Bacillus licheniformis BC98. Besides M. grisea, the isolate also inhibited the growth of other phytopathogens such as Curvularia lunata and Rhizoctonia bataticola. Biologically active fractions were isolated from the culture filtrate and further fractionated by reverse-phase high-performance liquid chromatography (HPLC) enabling detailed structural characterization of a component of molecular mass 1035 Da. The active peptide was identified as surfactin after 500 MHz ¹H NMR analysis. Microscopic analysis of the effect of the antagonist on M. grisea revealed bulbous hyphae showing patchy and vacuolated cytoplasm when observed under the electron microscope. The antagonistic lipopeptide secreted by B. licheniformis BC98 and identified as surfactin, induced morphological changes in M. grisea, inhibiting its further growth, and thus exhibiting fungicidal activity. The antagonist inhibits germination of M. grisea, a potent rice phytopathogen, and therefore appears to be a potential candidate for control of rice blast disease.