Comparison of biochemical properties of recombinant endoglucanase II of Trichoderma reesei in methylotrophic yeasts, Pichia pastoris and Hansenula polymorpha

Bioconversion of cellulosic material into bioethanol needs cellulase complex enzymesthat contain endoglucanase, exoglucanase and beta glucosidase. One of the most important organisms that produce cellulases is the filamentous fungi, Trichoderma reesei which able to secrete large amounts of different cellulases. These enzymes are probably the most widely used cellulases industrially, however, the cellulases excreted from fungi are not stable at high pH or high temperatures. In this study methylotrophic yeasts, Pichia pastoris and Hansenula polymorpha were used for the comparative heterologous production of endoglucanase II. Two synthetic egII genes with P. pastoris and H. polymorpha codon preferences were transferred into the yeasts. In addition, both expression vectors contained the pre-pro-sequence of Saccharomyces cerevisiae mating factor alpha to allow secretion of protein. Enzymes characterization demonstrated increasing thermal stability in both recombinants EGII compare with native enzyme from T. reesei and the Hansenula enzyme was more stable than Pichia in higher temperature. Biochemical properties determination on different substrates showed higher binding site affinity in Pichia than Hansenula and native one. We can conclude that P. pastoris and H. polymorpha are appropriate hosts for expression and production of endoglucanase with improved thermal stability.