Laurence Cheng Position/Title: PhD Student email: lcheng@uoguelph.ca Phone: Office:

I am currently a PhDstudent working under Dr. Ming Z. Fan at the University of Guelph focusing on swine nutrition. Originally born and raised from Markham Ontario, I recently graduated from the Animal Biology program at the University of Guelph in 2018. Outside of my studies I enjoy volleyball, basketball and daily trading in public stocks.

The aim of my research is to investigate the effects of a shortened processive cellulase called TmaCel5A on fiber digestion and growth in pigs after the weaning stage. Derived from Thermotoga maritima bacteria, this cellulose degrading enzyme (cellulase) was first investigated by Basit & Muhammad (2018) with positive results. Being processive, the enzyme is thus able to continue consecutively repeat enzyme activity on the same substrate chain without release of the chain and thus increase efficiency of the reaction.

Currently, the largest cost of a swine operation is feed. Successful degradation of cellulose/fiber in swine diets would allow usage of high fiber diets instead of costly conventional corn soybean meal feed if they provide similar nutritional content. Currently, high fiber diets have not been utilized due to nutrients being tied up in components such as cellulose. Thus the main purpose of my research is to utilize TmaCel5A to increase the nutritional value of alternative feed options thus lowering feed costs. In addition to this, successful degradation by TmaCel5A would have applications environmentally for treatment of cellulosic waste that would often be costly to burn and as an alternative for creation of sustainable biofuels from substrates that would otherwise be useless.

In order to investigate the effects of TmaCel5A, I first would test the viability of  TmaCel5A under physiological conditions and with various cellulosic substrates in vitro. To do this, I would incubate TmaCel5A with various substrates and measure the production of glucose equivalent products made from the reaction through a colour method. From this, I would be able to quantify the amount of product and activity of the enzyme. If successful I would formulate a high fiber diet with TmaCel5A and run an animal trial to examine growth and digestibility of various nutrients. These results would then be compared to values obtained from pigs fed a conventional diet.

So far, I have had very positive results working with carboxymethyl cellulose (CMC) substrate under physiological conditions. Although CMC is a fairly soluble cellulose substrate, this still provides positive results for TmaCel5A as a cellulase. In order to further enhance TmaCel5A activity, several purification steps have also been investigated with positive results. With success at this stage in my project, the next step would be to investigate other more insoluble cellulose substrates such as Avicel in vitro.