Impact of dilution rate on CGTase activity and productivity from an alkalophilic Bacillus sp. G1 in continuous culture

Khosiya Sali, Aidil Abdul Hamid, Wan Mohtar Wan Yusoff


Cyclodextrin glucanotransferase (CGTase) production by a locally isolated bacteriaBacillus sp. G1 was investigated in continuous culture with different dilution rates (D) (0.03,0.05, 0.07, 0.1, 0.3 and 0.5h-1). The CGTase activity profile was successfully maintained atsteady state using dilution rates of 0.03 to 0.3h-1. Maximum CGTase activity was obtained atlow dilution rate range (0.03-0.07h-1). CGTase activity decreased from 26.4 to 12.4 U/mlwhen the dilution rate was increased to 0.3h-1. The critical dilution rate (Dc) was establishedto be at dilution rate greater than 0.3h-1 and that the maximum CGTase productivity (Rmax)(3.72 U/ml/h) was achieved at 0.3h-1 dilution rate. This represented an increase of CGTaseproductivity by 4.8 times than that obtained at the dilution rate of 0.03h-1. We conclude thatthe CGTase productivity in steady state continuous culture can be readily achieved and thatthe impact of dilution rate is significant on activity and productivity.

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