GLBRC Conversion research aims to increase the quantity, diversity, and efficiency of energy products derived from plant biomass. Researchers focus on improving biological and chemical methods to convert plant material into advanced biofuels or valuable chemicals that can replace petroleum. Basic research discoveries that enhance the efficiency and sustainability of biomass conversion can break down barriers to developing economically viable biofuels technologies.
Scientific Director, Conversion Lead
Landick is an expert on structure, function and regulation of RNA polymerase, the central engine of gene expression. His work spans disciplines from single-molecule biochemistry to genome-scale mechanisms of gene regulation, and includes devising the first single-molecule observation of nucleic...
Within the Conversion group, researchers apply a combination of synthetic biology, directed evolution, systems biology, and computational modeling approaches to accelerate the rate and yield of microbial conversion of biomass to fuels. Microbial efforts focus on well-established models and biofuel-producing organisms to identify key genes and pathways that may illuminate opportunities for strain improvement. Chemical routes focus on direct catalytic conversion of biomass-derived sugars and lignin into liquid transportation fuels and/or high-value chemicals.
Specific Conversion projects fall in three categories:
- Engineering microbe strains to enhance stress tolerance and improve conversion efficiency of sugars to biofuels
- Developing flexible routes to biofuel production that can be adapted to diverse biomass feedstocks
- Producing light-driven and lignin-derived advanced biofuels, and using catalytic conversion to convert biomass to biofuels and value-added chemicals
Measurement of intrinsic catalytic activity of Pt monometallic and Pt-MoOx interfacial sites over visible light enhanced PtMoOx/SiO2 catalyst in reverse water gas shift reaction
Mechanism of imidazolium ionic liquids toxicity in Saccharomyces cerevisiae and rational engineering of a tolerant, xylose-fermenting strain
Imidazolium ionic liquids (IILs) underpin promising technologies that generate fermentable sugars from lignocellulose for future biorefineries. However, residual IILs are toxic to fermentative microbes such as Saccharomyces cerevisiae, making IIL-tolerance a key property for strain engineering. To enable rational engineering, we used chemical genomic profiling to understand the effects of IILs on S. cerevisiae.
We found that IILs likely target mitochondria as their chemical genomic profiles closely resembled that of the mitochondrial membrane disrupting agent valinomycin. Further, several deletions of genes encoding mitochondrial proteins exhibited increased sensitivity to IIL. High-throughput chemical proteomics confirmed effects of IILs on mitochondrial protein levels. IILs induced abnormal mitochondrial morphology, as well as altered polarization of mitochondrial membrane potential similar to valinomycin. Deletion of the putative serine/threonine kinase PTK2 thought to activate the plasma-membrane proton efflux pump Pma1p conferred a significant IIL-fitness advantage. Conversely, overexpression of PMA1 conferred sensitivity to IILs, suggesting that hydrogen ion efflux may be coupled to influx of the toxic imidazolium cation. PTK2 deletion conferred resistance to multiple IILs, including [EMIM]Cl, [BMIM]Cl, and [EMIM]Ac. An engineered, xylose-converting ptk2∆ S. cerevisiae (Y133-IIL) strain consumed glucose and xylose faster and produced more ethanol in the presence of 1 % [BMIM]Cl than the wild-type PTK2 strain. We propose a model of IIL toxicity and resistance.
This work demonstrates the utility of chemical genomics-guided biodesign for development of superior microbial biocatalysts for the ever-changing landscape of fermentation inhibitors.
Methodology for the experimental measurement of vapor-liquid equilibrium distillation curves using a modified ASTM D86 setup