By Ryan Tam – Chemical Engineering Student @ Trinity College, Cambridge
Enzymes are biological catalysts that help speed up the rate of metabolic reactions within the body. The substrate, which is the molecule being broken down, fits into the active site of the enzyme like a lock and key mechanism. The human body is known to produce over a thousand enzymes, however, one enzyme it does not produce is cellulase.
Cellulase catalyses the decomposition of cellulose into simpler sugars and is produced by many types of different bacteria and fungi. The bacteria in our large intestine are able to digest some of the dietary fibre that we consume, which consists of cellulose. Cellulose is also present in the cell walls of yeast cells belonging to the Genus Candida; these are the types of pathogens responsible for causing genital yeast infections, athlete’s foot, and oral thrush.
The cell walls of yeast cells contain beta-glucans, which is a long-chain polymer consisting of beta-glucose; cellulose is a type of beta-glucan. The biofilm produced by these yeast cells also contains high levels of cellulose, which shields the yeast cells from the human immune system and allows them to grow unhindered. The cellulase enzyme is able to break down the cell wall of the yeast cells, and can also make the biofilm layer thinner, thereby exposing more of the pathogens to the immune system.
One advantage of using enzymes during treatment is that the yeast cells are unable to build resistance towards cellulase, unlike antifungal drugs. The presence of cellulase does not harm the human body, nor does it cause the pathogens to mutate. Ingesting the enzyme may also be more useful for treating fungal infections, especially genital and oral thrush, where antifungal creams may not be the most comfortable method of treatment.
However, ingesting too much cellulase can severely decrease the level of naturally occurring yeast in the alimentary canal, and affect the movement of dietary fibre through our digestive system. The enzymes should be taken in conjunction with probiotic supplements containing Lactobacillus bacteria, which improve intestinal health and fight off unwanted microorganisms.
Part of the work of chemical engineers and pharmaceutical scientists includes efficiently scaling up small-scale experiments and determining a way to produce a chemical product economically and practically at a commercial level. Through rigorous testing of multiple strains of bacteria and fungi, a few species have been chosen for use in industry. These species produce the largest amount of cellulase given the same amount of starting material and then undergo further genetic modifications in order to improve their enzyme-production capabilities.
These microbes naturally produce cellulase when placed in contact with organic matter or synthetically produced pure cellulose. This process occurs in large fermenters, where the cells digest the available cellulose by secreting cellulase into the reaction medium. The enzyme is a catalyst, so it is not consumed and remains in the reaction medium throughout the reaction. From here, the microbial suspension is placed into a centrifuge in order to separate the microorganisms from the rest of the mixture. The liquid layer containing the enzymes and reaction products is then extracted, from which it is further purified to obtain the cellulase enzyme.
Further Reading:
1. https://ndnr.com/gastrointestinal/candida-and-proteolytic-enzyme-therapy/
2. https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-017-0717-0