6-03: Microfluidic high-throughput assays for biomass-to-biofuels conversion

The hydrolysis of biomass to fermentable sugars using glycosyl hydrolases is a limiting and costly step in the conversion of biomass to biofuels. Enhancement in hydrolysis efficiency is necessary and requires improvement both in enzymes and processing strategies. Advances in both areas in turn strongly depend on the progress in developing high-throughput (HTP) assays to rapidly and quantitatively screen large number of enzymes and processing conditions.

We have developed novel microfluidic platforms to address the throughput limitations of conventional technologies. By performing in-situ biomass regeneration in micro-volumes, we have developed a HTP approach for volumetric metering of biomass at sub-mg loading. In addition, we have developed a microfluidic device for rapid, precise, multiplexed, and high-throughput screening of lignocellulolytic enzymes and for characterization of biomass. Our microfluidic devices and assays have vastly superior performance compared to conventional approaches such as HPLC and colorimetric assays. For example, the run-time per sample is around 60 s (> 10X faster than HPLC) and the detection sensitivity is around 1 amol (100X smaller reagent volume than HPLC). In addition, we have developed a microscale platform, based on cell-free protein expression, which seamlessly integrates cellulase expression and activity screening without the need for any protein purification procedures. Starting from cellulase DNA templates, our approach achieves transcription, translation, and activity screening of generated cellulases within 2-3 hours in 2-3 μL volumes, thereby significantly reducing reagent usage and costs. We are using the microfluidic assays for large-scale screening and characterization of substrate-enzyme interactions for developing optimized cellulase cocktails.