Oxidoreductases in biomass saccharification processes

The inauguration of several commercial scale lignocellulosic ethanol factories within the past few months is a clear sign of the emergence of an industry. The development of an industry is likely to call for further studies of the fundamental principles governing the processes in order to facilitate further optimisation and thus competitive edge. Although impressive improvement in the efficiency of enzyme cocktails for lignocellulose deconstruction has been achieved already, the understanding of this process step is still incomplete. A recent development is the discovery of lytic polysaccharide monooxygenases which has opened a vide avenue for further studies of the mechanism by which plant cell wall are deconstructed in nature as well as in industrial settings. This is truly a new avenue within cellulase research which was in the past exclusively devoted to the study of hydrolases. Other oxidoreductases may also have a role to play. In nature, cellulytic LPMOs work in cooperation with another oxidoreductase, namely cellobiose dehydrogensase, but how the enzymes interact is inadequately described. In addition it has also been reported that laccase and peroxidase may have a positive effect on the saccharification efficiency but the mechanism behind is not understood in detail. The use of oxidoreductases in the production of lignocellulosic ethanol will be discussed in light of current scientific thinking and new insights.