Team:Imperial College London/M1/Cellulase
From 2009.igem.org
Cellulase
Ruminants survive on a diet high plant matter through the breakdown of cellulose and xylan by their gut microflora. Non-ruminants, such as humans, are unable to release much of the energy found in these compounds, and so must rely on an omnivorous diet. Of course, the transfer of energy between trophic levels is notoriously poor. If non-ruminants were able to obtain more energy from plant matter, the net effeciency of energy transfer would be raised reducing the volume of food required in a diet. In addition, polysaccharides such as cellulose form viscous gel-like structures that trap starch, proteins and fats which would otherwise be accessible to the animal's digestive enzymes and transport systems.
Cellulases are often added to chicken feed in order to get the maximum possible nutritional content from the food. This is widely used, especially with diets high in non-starch polysaccharides. This allows the tough cellulose cell walls to be broken down, and allows the nutrious contents to be absorbed.
Our solution would be in the form of a dietary supplement to be taken alongside foods with high cellulose contents, to allow for digestion of the cellulose within the gut. This would be especially beneficial in countries with less refined and processed diets.
Cellulases come in a number of types, and break down cellulose in different ways to different extents. The cellulase we have chosen is endo-b-1,4-glucanase E (CelE) cellulase, which is one of the three major proteins of the cellulosome of Clostridium cellulolyticum. This cellulase is also protease resistant, making it ideal for use with The E.ncapsulator's production and delivery mechanism. CelE mainly catalyses the reactions that changes crystalline cellulose to cellobiose and then finally to glucose. It also catalyses, to a small extent, the break down of carboxymethyl cellulose.