Strain improvement of chitinolytic enzyme producing isolate Pantoea dispersa for enhancing its biocontrol potential against fungal plant pathogens

Pantoea dispersa was mutated by physical as well as chemical mutagens. Ultraviolet and gamma rays were used as mutagens separately for wild type strain of Pantoea dispersa and EMS (chemical mutagen) was used for the further mutation of mutant obtained from the physical mutagenesis. Mutants were screened as chitinolytic producers on the basis of zone of clearance on chitin agar plates incorporated with calcofluor white M2R for better resolution. Through shake flask, it was found that the gamma mutant no. 8 was found to produce 11.65 +/- 0.16 IU/ml of chitinolytic enzyme, which was higher than UV mutant 19 (9.52 +/- 0.21 IU/ml). Gamma mutant no. 8 was further mutagenized by EMS mutagenesis and EMS mutant no. 10 was found to produce 13.97 +/- 0.25 IU/ml of chitinolytic enzyme. Through successive subculturing, the stability of the mutants was checked for over 5 months. These mutants were found to produce higher protease and beta-1,3-glucanase as compared to wild type. The mutant strains were further used in studies involving control of the fungal plant pathogens such as Fusarium sp. and Macrophomina phaseolina (Tassi) Goidanich a root borne plant pathogens of Cajanus cajan by in vitro study. The mutant EMS 10 culture has better potential in inhibiting the growth of Fusarium sp. and M. phaseolina as compared to other mutants. Inhibition of hyphal elongation by culture filtrate was demostrated microscopically.