Purification and Partial Characterization of Antifungal Peptides from Soybean Endophyte-Paenibacillus sp strain HKA-15^†

Culture supernatant of soybean nodule endophytic bacterium Paenibacillus sp strain HKA-15 showed the antifungal activity against Rhizoctonia bataticola, the causative agent of charcoal rot disease in soybean. The activity was detected only during the on set of stationary phase (24h post inoculation) in potato dextrose broth. The culture filtrate was extracted with nbutanol, resolved into two compounds by hydrophobic interaction column (Sephadex LH-20) chromatography and purified by reverse phase HPLC. Bioactive fractions collected from preparative HPLC were characterized as cyclic peptide and depsipeptide. No loss of activity was recorded with these metabolites when exposed to proteinase K, glycerol (50%), sodium dodecyl sulphate (1%), triton X-100 (1%) and wide pH range.