5-61: Characterization of the specific activities and hydrolytic properties of the cell-wall degrading enzymes produced by Trichoderma reesei RUT C30 on different carbon sources

Conversion of lignocellulosic substrates to biofuels requires efficient cell wall degrading enzymes at reasonable price, and among the possibilities are enzymes produced in situ on available lignocellulosic substrates. Cellulases and hemicellulases were produced by fermentation of Trichoderma reesei RUT-C30 on different carbon sources: steam pretreated corn stover (SPCS), Solka Floc 200 (SF) and lactose. The produced enzymes were characterized by their specific enzyme activities. Enzymes produced on Solka Floc and SPCS had similar FPU activities and protein content, and were rich in xylanase, while enzymes produced on lactose had significantly lower cellulase activity per unit volume. Substrates containing xylan led to an increased secretion of xylanase and ß-xylosidase, whereas enzymes produced on lactose had highest specific β‑glucosidase and CBH I activities.

The hydrolytic properties of the enzymes were compared with the commercial Celluclast 1.5L on four substrates: SPCS, steam pretreated spruce (SPS), SF and Avicel using a standard FPU loading. Enzymes produced on the lignocellulosic substrates performed generally better than the commercial one. As expected, the substrates containing xylan were clearly hydrolyzed more efficiently with enzymes rich in xylanases, whereas the cellulosic substrates depended more on the cellulase enzyme pattern. Hydrolysis of SPCS and SPS was also performed with various enzyme preparations (Celluclast and the enzymes produced on SPCS and SF) by adjusting with purified enzyme components the xylanase and ß-glucosidase levels to reach similar activity levels. The results lead to further understanding of the hydrolytic mechanisms and the factors determining the performance of different mixtures of T. reesei enzymes.