Production of cyclodextrin glucanotransferase from alkalophilic bacillus sp. Ts1-1 using fed batch culture

Abstract

The study of fed batch fermentation was carried out to enhance the production of CGTase from Bacillus sp. TS1-1. The microbes was grown in 2 %(w/v) soluble starch, 11%(w/v) yeast extract, 0.1 %(w/v) K2HPO4, 0.02 %(w/v) MgSO4.7H2O and 10 %(w/v) Na2CO3 solution. Batch fermentation was carried out as control using 5 L fermentor with 4 L working volume. A maximum CGTase activity of 70.32 U/ml was observed during the stationary phase of growth with specific activity of 0.198 U/µg proteins. The fed batch study was carried out to obtain the best feeding mode, carbon and nitrogen sources. Constant feed rate fed batch result gave the highest increment in CGTase production by 25.3% as compared to the batch fermentation. Tapioca starch at concentration of 2 %(w/v) was selected as the best inducer for both CGTase and biomass production, where improvement of 35.6% and 25.7% was observed respectively, as compared to the batch fermentation. The addition of 0.5 %(w/v) nitrogen source in the feeding medium failed to improve the CGTase production, but on the other hand increased the biomass significantly. An increment of 69.3% in terms of biomass production as opposed to batch fermentation was obtained with yeast extract. The optimization of carbon and nitrogen concentration using tapioca starch and yeast extract was carried out using Response Surface Methodology (RSM). The optimum condition obtained were 3.3 %(w/v) of tapioca starch and 0.13 %(w/v) of yeast extract. The optimized medium improved the CGTase production up to 13.9% as compared to batch fermentation. The production of CGTase in repeated fed batch fermentation using 2 %(w/v) of tapioca starch was quite consistent even after the third addition of fresh medium with maximum activity fluctuating between 80 - 86 U/ml.