OPTIMIZATION OF PROCESS PARAMETERS FOR MAXIMUM PRODUCTION AND CHARACTERIZATION OF DEXTRANSUCRASE FROM NEWLY ISOLATED ACETOBACTER TROPICALIS

摘要

The potent producer A. tropicalis was isolated and selected on the basis of high dextransucrase activity. Different physicochemical parameters for A. tropicalis dextransucrase production have been optimized. A. tropicalis showed maximum dextransucrase activity (4.58 U/mL) when incubated for 8 h at 25 oC in medium having initial pH 7. The 26 technological combinations were also designed to study the effect of physical and chemical parameters in combination which proved to be very satisfactory on economical point of view. The selected combination gave 21.2 folds increase in dextransucrase activity over the basal medium (0.23 U/mL) and more activity than the medium formed after studying the effect of individual physicochemical parameters. Optimum reaction conditions for maximum dextransucrase activity were found to be 25 mM sodium acetate buffer with pH 5.5, reaction temperature 37 oC and sucrose concentration 2% (w/v). Optimization of reaction conditions resulted in maximum 12.2 U/mL dextransucrase activity. This activity was higher than the activity reported previously for other strains. Crude dextransucrase A. tropicalis showed Km=29.86 mM and Vmax=7.0 U/mL . This is the first report on dextransucrase production by A. tropicalis.