Production and Characterization of an Antifungal Compound from Pseudomonas protegens Strain W45

Pseudomonas protegens strain W45 recovered from rhizosphere of wheat possesses potential to produce an antifungal compound in the culture medium. Therefore, to enhance its production, statistical optimization of medium was employed. Peptone, glycerol and incubation period were identified as significant variables affecting its production. These variables were further optimized by response surface methodology that resulted in 38% enhancement in inhibition zone with optimal values of 2.5%, 1.49% and 48 h for peptone, glycerol and incubation period, respectively. PCR amplification by gene specific primers for phloroglucinol, pyrrolnitrin and pyoluteorin resulted in amplicon of 745, 719 and 773 bp respectively, confirming the presence of all three genes. Antifungal compound was purified by thin layer chromatography. Gas chromatography mass spectrometry analysis of the methanolic extract reveals the presence of pyrrole type antifungal molecule 3-(2-methylpropyl)-hexahydropyrrolo [1,2-a]pyrazine-1,4-dione (C11H18N2O2). The compound significantly inhibited the growth of Sclerotinia sclerotiorum.