Byline: Amrit Mehta, Biology MSc. student
The decline in reserves, rising cost of fossil fuel extraction and export, and the environmental impacts of their continued use are making alternative fuel more appealing. The push now is to be able to convert cellulose-containing waste into biofuels.
Waterloo researchers are trying to modify enzymes from heat-loving microbes to improve the efficiency of converting cellulose-containing biological waste into biofuel.
Navin Asokumar, a Biology Master’s student in Prof. Kesen Ma’s lab, is improving a method to convert plant mass into fuel by modifying an alcohol-producing enzyme from two hyperthermophiles, Thermococcus guaymasensis and Thermotoga hypogea.
When we finish we will hopefully drastically reduce the cost and labour of producing biofuel while at the same time increasing yield and efficiency.
These heat-loving microbes produce an alcohol-producing enzyme that requires a strict oxygen-free environment in order to function. Though it’s possible to create such an environment in a laboratory or industrial setting, the associated costs and maintenance are what make the option of converting of bio-waste to biofuels financially unappealing.
The current major source of biofuel production comes from plants with high sugar content, such as sugar cane and corn. Through fermentation and distillation, ethanol is produced as fuel from those sugars. However, the yield of these high sugar crops is low and the current process is expensive.
Cellulose is the most abundant plant structural polysaccharide on the planet, making up all plant walls. Its abundance, access and composition as a carbon-based polymer make it an ideal target for biofuel production. A promising new method uses microbes to break it down and convert substrates at the molecular level.
Waterloo biologist Asokumar (pictured above) is trying to improve a process converting plant mass into fuel. The first step of the process uses heat or chemicals to remove the lignin content of the plant mass and separate it into liquid and solid portions. It is the lignin which creates the bottleneck in the production of biofuels as it decreases accessibility to the polysaccharides of the plant.
The second step involves the conversion of the accessible sugars released to alcohols. It’s in the second anaerobic step, where pyruvate is converted into ethanol in an environment that lacks oxygen, and this is the focus of Asokumar’s research.
Asokumar is currently working on modifying the alcohol dehydrogenase enzymes from two hyperthermophilic, or heat-loving microbial species – T. guaymasensis and T. hypogea. The enzymes from these specific species are involved in the conversion of pyruvate to ethanol and are sought because they are able to remain active at temperatures nearing 80ᵒC; however, they require an anaerobic environment, devoid of oxygen.
To do this, Asokumar and colleagues will modify the enzyme so it’s more active in aerobic, or oxygenated, environments, helping increase yield and simplify operation procedures.
My overall objective is to convert the anaerobic enzyme I'm working with to be more active under aerobic condition,” says Asokumar. “Economic-wise, aerobic conditions are easy to handle and more cost effective.
The heavy reliance on fossil fuels for energy will also be reduced, which will be a major breakthrough and stimulus for up-and-coming global economies with increasing energy demands like India and China. The work that Asokumar and colleagues are doing has the power to change the world.
NOTE: BIOL 690 Scientific Communication is a graduate course that helps students enhance their skills in the acquisition, organization and presentation of scientific information. Students in the course interviewed and wrote a news story about one of their classmates' research.