468094 Enabling Microbial Utilization of Thermally Depolyermized Lignin Monomers

Tuesday, November 15, 2016: 9:45 AM
Union Square 21 (Hilton San Francisco Union Square)
Kirsten Davis1, Marjorie Rover2, Davinia Salvachua3, Gregg T. Beckham3, Zhiyou Wen4, Ryan Smith2, Laura Jarboe1 and Robert Brown2, (1)Chemical and Biological Engineering, Iowa State University, Ames, IA, (2)Bioeconomy Institute, Iowa State University, Ames, IA, (3)National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, (4)Food Science and Human Nutrition, Iowa State University, Ames, IA

The lignin component of biomass is an attractive source of carbon and energy for the microbial production of fuels and chemicals. This adding of value (valorization) to lignin by biological conversion can increase the overall economic viability of biorenewable fuel and chemical production. Thermal depolymerization of biomass through fast pyrolysis shows promise in terms of its ability to recover aromatic monomers from the lignin component of the biomass. Specialized microbes, such as Pseudomonas putida KT2440, can utilize many of these aromatic monomers when provided in pure culture [1,2]. However, microbes can be negatively affected by toxic impurities in biomass derived streams, and lignin rich pyrolysis fractions are insoluble in water and therefore inaccessible to microbes in liquid culture medium. Here we addressed these toxicity and insolubility issues by developing and testing an emulsion formula which granted P. putida KT2440 access to the phenolic monomers. The optimized emulsion formula contained 18.2 MΩ water, a 70:30 ratio of Tween20® to Span80® surfactant, and the lignin rich pyrolysis fraction. P. putida KT2440 was able to use this emulsion formulation as sole carbon source. Additionally, studies with a pure aromatic monomer, p-coumarate, indicated that the emulsion procedure at least partially protects P. putida KT2440 from the substrate toxicity of this monomer. To minimize surfactant cost, the surfactant amount was minimized to 7 wt% of the total lignin rich pyrolysis fraction weight. This emulsification method is an important step in enabling the biological valorization of biomass-derived lignin.

Refs: 1. Johnson, C. W.; Beckham, G. T. Metabolic Engineering 2015, 28, 240-247. 2. Vardon, D. R.; Franden, M. A.; Johnson, C. W.; Karp, E. M.; Guarnieri, M. T.; Linger, J. G.; Salm, M. J.; Strathmann, T. J.; Beckham, G. T. Energy & Environmental Science 2015, 8, (2), 617-628.

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