Chemical and Biomolecular Engineering Faculty Research

Title

Wastepaper Hydrolysate as Soluble Inducing Substrate for Cellulase Production in Continuous Culture of Trichodermareesei

Document Type

Article

Publication Date

Fall 1999

Abstract

The enzymatic hydrolysate of wastepaper was evaluated for its cellulase-inducing capability and production characteristics in continuous culture of Trichoderma reesei RUT C30. Under the study conditions, i.e., pH 5.0, temperature 25 °C, and typical medium C:N ratio, the apparent cell yield constant was found to be 0.76 (g of dry cell weight/g of reducing sugar), and the maximum specific cell growth rate was 0.26 h−1. The study on the effects of medium C:N ratio confirmed an important role of N sources in the cellulase synthesis. The cellulase production decreased significantly when the feed concentrations of N sources were reduced. An experiment at pH 7.5 with 4-fold N source concentrations also led to poorer cellulase production. When compared with cellulose, the wastepaper hydrolysate was found to have similar cellulase-inducing strength and to induce an apparently complete set of cellulase components. The hydrolysate was also concluded to be a better soluble inducer than sophorose. While comparable at a low dilution rate (0.012 h−1), the specific cellulase productivities of the hydrolysate-supported and the sophorose-induced systems exhibited opposite trends with increasing dilution rates. The specific productivity in sophorose-induced systems decreased with an increase in the dilution rate. On the other hand, with increasing dilution rate the specific productivity in the hydrolysate-supported systems increased from 2.2 FPU/g·h at D = 0.012 h−1 to 12.2 FPU/g·h at D = 0.122 h−1before beginning to decline. The initial increasing trend was attributed to the higher concentrations of inducing oligomer intermediates at larger dilution rates.

Volume

15

Issue

1

First Page

91

Last Page

97