Formulation of medium constituents by multiresponse analysis of central composite design to enhance chitinase production in Pantoea dispersa.

In the present study, a high chitinase producing strain Pantoea dispersa was isolated from the sea dumps at Bhavnagar, India. Chitin, urea, CaCl2 and MgSO4 x 7H2O were variables used in central composite design for chitinase production. Chitinase, biomass and pH were the responses used in different models to evaluate individually fit ones. Quadratic model was found to be fit for chitinase response whereas in the case of biomass and pH, linear model was found to be fit without the effect of others. Chitinase production was optimized with respect to other responses such as biomass and pH in multiresponse analysis of response surface design by using desirability approach. In multiresponse analysis, following medium formulation (g/l), chitin, 15; urea, 0.32; CaCl2, 0.10 and MgSO4 x 7H2O, 0.08 was found to predict optimum chitinase production of 482.77 units/ml with overall highest desirability of 0.854 as compared to other formulations. The selection of model was done on the basis of high Adjusted R-squared value and lowered p-value for each model in individual analysis of each response. In multiresponse experiment, it was found that for response chitinase quadratic model and for responses pH and biomass linear models were well fit. Through desirability analysis, it was found that in the chitinase production, pH was essential as compared to biomass in P. dispersa. Endochitinase and chitobiase actvities were also studied.

Isolation and identification of marine chitinolytic bacteria and their potential in antifungal biocontrol.

Chitinolytic marine bacterial strains (30) were isolated from the sea dumps at Bhavnagar, India. They were screened as chitinase producers on the basis of zone of clearance on chitin agar plates incorporated with calcofluor white M2R for the better resolution. Out of these, three strains namely, Pseudomonas sp., Pantoea dispersa and Enterobacter amnigenus showed high chitinase production. They were also found to produce proteases and therefore have a good potential for use as antifungal biocontrol agents for the control of fungal plant pathogens. These strains could degrade and utilize the mycelia of Macrophomina phaseoliena (Tassi) Goidanich and Fusarium sp. In vitro, these strains could inhibit the growth of Fusarium sp. and M. phaseolina. The culture filtrate inhibiting hyphal elongation was observed microscopically.