Production of cellulase enzyme from lactose in batch and continuous cultures by a partially constitutive strain of Trichoderma reesei

Abstract

The present studies concern the production of cellulases, in batch and in continuous cultures, using a mutant strain T. reesei C-5 growing on soluble carbon substrate, lactose. The maximum specific growth rate ( μ max ) and saturation constant ( K s ) in continuous culture at 2% feed lactose were estimated to be 0.066 h −1 and 1.17 g l −1, respectively. The corresponding values in batch culture on 4% lactose were estimated to be 0.067 h −1 and 1.36 g l −1, respectively, and the corresponding overall growth yield factor ( Y 0) was found to be 0.63 g cell g loctose −1 (in 60 h). The volumetric enzyme productivity ( E), and specific enzyme productivity ( v) in continuous culture with 2% feed lactose were found to be 51.52 IU l −1 h −1 and 4.58 IU mg cell −1 h −1, respectively, and the corresponding values with 4% feed lactose were estimated to be 56.02 IU l −1 h −1 and 2.68 IU l −1 h −1, respectively. From the pulse response of 0.2% glucose, partial catabolic repression was noticed. The addition of 0.2% cellulose produced an inducing effect for enzyme synthesis. It was noticed that T. reesei C-5 is a highly derepressed mutant strain capable of synthesizing active cellulases on soluble sugar lactose.