Transforming Living Materials into Chemical Reactors

Project Overview

Methane is a potent greenhouse gas that contributes significantly to global climate change. Conversion of methane into value-added liquid products can reduce emission and generate extra revenue at the same time. For small-scale emission sources, a low-cost biological conversion approach through engineered methanotrophs represents an attractive solution. However, this technology cannot be commercialized using existing bioreactors, because conventional stirred tank bioreactors are slow in gas reactions, resulting in low volumetric productivity and therefore are not economically viable. To realize the potential of waste methane to valuable project conversion via high efficiency biocatalysis, the goal of this project is to create an innovative and versatile platform to study the fundamental science of designing and understanding living materials for catalysis.

Our novel bioreactor concept addresses directly the two most key issues in stirred tanks, cell density and gas-to-liquid mass transfer. We developed new living materials, that is, biocompatible hydrogel encapsulating live methanotrophs, with 50-fold increase in cell density to substitute for suspended cell culture. Combining additive manufacturing techniques and simulation, we created gas-permeable three-dimensional geometries featured with large surface area, enhanced gas transport, and structural robustness. Infiltration of living materials into printed geometries generated small yet highly biocatalytic units, within which methane conversion took place. Tests under both static conditions showed these solid-state biocatalytic units exhibited one to two orders of magnitude better performance of methane consumption rate and organic acid titer over liquid culture. These results validate the solid-state bioreactors design to facilitate gas transfer, provide scientific insights in immobilized microbe growth, production, and product recovery for advanced flow reactor design, and also open up new possibilities for field-scale biogas conversion at small methane sources into salable products. The concept and new science achieved from the reactors are general and can be transferred to a variety of gas-involved biosynthesis processes using living microorganisms.

Mission Impact

This project directly addresses the Laboratory's core competency in Advanced Materials and Manufacturing, as well as its mission research challenge in energy and resource security under the materials for energy applications thrust. It will help Lawrence Livermore National Laboratory maintain a leadership role in waste gas stream-to-product conversion technologies. This role is of great interest to Livermore's E program and others because of the ever-increasing concern of global climate change and energy shortage. The Center for Engineered Materials and Advanced Manufacturing in the Engineering Directorate has benefited from sustaining the tools that demonstrate the applications of advanced manufactured materials. This project will also position the laboratory for new initiatives in the areas of: CO2 and methane utilization led by DOE-BETO, Process Intensification led by AMO, and the construction of modular reactors (of interest to Fossil Energy and others).

Publications, Presentations, and Patents

Fang Qian, Cheng Zhu, Jennifer Knipe, et al. 2019. "Direct Writing of Tunable Living Inks for Bioprocess Intensification," Nano Letters 19, 5829-5835. doi.org/10.1021/acs.nanolett.9b00066.

Lattice Microfluidics. Josh DeOtte, Sarah Baker, Jennifer Knipe, Fang Qian, Samantha Ruelas, Patent No: US 11,130,131 B2.

Jennifer M. Knipe, Samantha Ruelas, Hawi Gemeda, et al. "Transforming Living Methanotrophs into Chemical Reactors." In 2019 AIChE Annual Meeting (ISBN: 978-0-8169-1112-7).

Fang Qian, 2020. "Printed Bioreactor: Improving gas-to-liquid mass transfer for efficient methane conversion." In LLNL Carbon Initiative Seminar series.

Nathan C. Ellebracht, Fang Qian, Samantha Ruelas et al. "Gas to Liquid Flow Reactor for Conversion of Biogas or Waste Methane to Organic Acids with Hydrogel-Encapsulated Methanotrophs As Fixed Biocatalysts." In 2020 Virtual AIChE Annual Meeting (ISBN: 978-0-8169-1114-1).