Lignin to Fuels and Chemicals -- Converting the waste material to the valuable

J.S. Yuan
Texas A&M University, US

Keywords: lignin, biofuel, PHA/B, waste management, biofuel, paper pulping

Summary:

The technical profolio addresses one of the most challenging issues in lignocellulosic biofuel production: the use of lignin for fungible fuels and chemicals. Despite significant advances in processing carbohydrate in lignocellulosics, the utilization of lignin for fungible fuels or chemicals has yet to be achieved. At best, lignin is utilized as a low-value thermal resource for powering its associated manufacturing processes. However, modern biorefineries for cellulosic ethanol have ~60% of excess lignin. Moreover, lignin is already a major waste for the paper pulping industry. An enabling lignin processing stream will both reduce the cost for biofuel production and simplify the waste management in both biofuel and paper pulping industries. We have developed two complementary platforms for converting lignin to lipid and PHA/B, respectively. For both technologies, synthetic microbes were engineered with lignin depolymerization, aromatic compound degradation, and target compound production capacities. For the first platform, rhodococci strains were engineered to reach the conversion of nearly 40% lignin to produce lipid at 30% of cell dry weight by combining all three synthetic modules together. For the second platform, a unique Pseudomonas strain out of screening was engineered to convert about 20 to 30% of lignin into high yield of PHA/B.