Effects of shear stress and mass transfer on chitinase production by Paenibacillus sp CHE-N1

Chitinase fermentations with strain Paenibacillus sp. CHE-N1 was carried out in a 5-1 stirred-tank bioreactor. The effects of operation variables including agitation rates, aeration rates, and pH values, on cell growth and chitinase activity yield were evaluated. Oxygen transfer limitation was predominant when the fermentation was carried out at low agitation rate (100 rpm). At agitation rate of 300 rpm, the high shear stress was dominant. Decrease chitinase production and extensive sporulation along with cell degradation were observed. When the pH was controlled at a constant (6.0-9.0) during the cultivation, lower chitinase production was obtained. The operation conditions at an aeration rate of 3 vvm, an agitation rate of 200 rpm, and without pH control could yield an optimal chitinase activity level of 11.8 U/ml. (c) 2006 Elsevier B.V. All rights reserved