SYNTHESIS OF CYCLODEXTRIN GLUCOSYL TRANSFERASE BY BACILLUS-CEREUS FORTHE PRODUCTION OF CYCLODEXTRINS

A potent indigenous bacillus isolate identified as Bacillus cereus (RJ -30) was found to produce Cyclodextrin Glucosyl Transferase (CGTase) e xtracellularly. Process optimization of various fermentation parameter s has been established for optimal growth of bacillus and the maximum enzyme synthesis. The organism had the highest specific growth rate (0 .7 mu) with a generation time of 1 h in glucose containing medium at t he conditions of pH 7.0, 37 degrees C at 300 rpm, 1.5 vvm of agitation , and aeration. At these conditions, it exhibited the maximum activity of 54 U/mL at the synthesis rate of 2.7 U/L/h. CGTase was produced fr om the early exponential growth and peaked during the midsporulating s tage of about 16 h thereafter maintained at the same level of 50 U/mL. Saccharides containing media were better inducers than starch, and th e influence of carbohydrate substrates has shown that enzyme synthesis is promoted by xylose (65 U/mL) and, more remarkably, by the suppleme ntation of wheat bran extract in glucose medium (106 U/mL). This organ ism produced CGTase stably in a chemostat culturing over a period of 4 00 h with a maximum productivity of 5.4 kU/L/h (threefold higher than obtained in batch culturing [1.75 kU/L/h]). Comparatively, CGTase was produced by immobilized cells in a continuous fluidized bed reactor fo r over approx 360 h, at a relatively high dilution rate of 0.88 h(-1) resulting in the productivity of 23.0 kU/L/h.