Degradation of cellulose
In nature, the oyster mushroom grows on dead trunks of trees where the lignin and cellulose ?the two principal components of wood - are being broken down. Degradation of lignin has been studied over the years by a number of research teams that have characterised the genes involved. But nobody, to date, has tackled the degradation of cellulose from a molecular perspective.
Cellulose is the most abundant biological polymer on the planet. It is made up of units of D-glucose united by means of glycosidic links that form long polymer chains. The breaking down by live organisms takes place through the action of three types of enzymes: endogluconases, cellobiohydrolases y b-glucosidases.
All these, necessary for the complete breaking down of cellulose, function by hydrolysing the glycoside links, but they vary in the specificity of substrate: the endoglucanases attack the glycosidic links within the cellulose molecule, the cellobiohydrolases act by liberating units of cellobiose from either end of the cellulose chain and the b-glucosidases hydrolyse the cellobiose molecules, producing glucose as end product.
In her PhD thesis Arantza Eizmendi Goikoetxea has analysed the activity of one of these types of enzymes: the cellobiohydrolases. To this end, she cloned, isolated and sequenced those genes of the oyster mushroom responsible for this activity and investigated the cult