Team:Purdue/ProjectDevelopment

• INTRODUCTION
• BACKGROUND
  • The Problem
  • Organisms
  • Enzymes
• PROJECT
  • Description
  • Project Development
  • Our Solution
• PARTS
  • Team Parts
  • Basic Parts
  • Composite Parts
  • Part Collection
  • Parts Used
  • Parts Submitted
• NOTEBOOK
• ATTRIBUTIONS
• OUR PROCESS
• HUMAN PRACTICES
• SAFETY
• MODELING

Project Development

The Biomakers started their project development from a human practices perspective, thinking of five broad areas to search for problems in: energy, food, waste, water and livestock. Ideas panned out from each of these categories but one that garnered a lot of interest was the use of biodigesters as a means of agricultural and municipal waste management.

The focus then shifted to assessing the major issues within biodigesters. After learning about the benefits of codigestion, it was decided to focus in one the major issue with dealing with plants in biodigestion: the difficulty of lignin degradation.

The search for lignin-degrading solutions ended in a meeting with Dr. Michael Schart (Department of Entomology, Purdue University). Dr. Scharf’s research revolves around the identification of lignin-degrading enzymes in termites. The project idea began to form from this meeting: a synthetic yeast system that produces and secretes lignin-degrading enzymes as an enzymatic alternative for thermal pretreatment.

Although the termite enzymes were strong candidates, the search was widened for any woody-plant-eating species and their lignin-degrading enzymes. With a wide field, design criteria were set for enzymes that operate at neutral pH and room temperatures, conditions that would make the project more feasible and easier to test. These criteria narrowed the field to genes from both termites and various white rot fungi.

At this point, the idea seemed to be coming along fairly well until we met with Dr. Nate Mosier (Department of Agricultural and Biological Engineering, Purdue University), who gave some perspective on why enzymatic pretreatment is so difficult: the byproducts of lignin degradation inhibit cellulase enzymes, so degradation of lignin polymers can actually and has been proven to lower the conversion rate of cellulose into ethanol. This new information provided a major roadblock, one which was thought to be an end to a viable project based on synthesizing lignin-degrading enzymes, when a significant piece of work in the literature arose in the search.

The J4 yeast, co-developed by synthetic biologists at University of Illinois, University of California Berkeley, and a few others, is a strain of synthetic yeast that internalizes the conversion of cellulose into ethanol from the stage of cellobiose (cellulose disaccharide) to the final stage of ethanol. The internalization meant that, if the lignin was degraded in the exterior of the cell, the byproducts could not interfere with the enzyme activity going on inside the cell: the project was back on track.

This discovery refined the project and contextualized the end goal of creating a strain of synthetic yeast that would complement the J4 strain, filling in the last piece of the puzzle from woody material to useful biofuel. This would complete the picture of a simplified biofuel conversion process that is based on only one easily engineered species, rather than depending on the natural host of organisms found in current biodigesters. This simple yet easily modified platform would then open up new possibilities for biofuel conversion optimization, fulfilling the mission of making biofuels a more viable energy alternative.