Production and Engineering of Hydrogenase as a Biocatalyst for Hydrogen Fuel
Hydrogenases are fascinating redox proteins, showing tremendous promise in the utilization of hydrogen fuel as a bioelectrocatalyst. They play critical roles in both biohydrogen production and hydrogen oxidation. Specifically, the recently-established comparability of the oxidative activity of the [NiFe]-hydrogenase active site to that of the fuel cell catalyst platinum marks a significant milestone for the potential application of hydrogenase in hydrogen fuel cells to replace platinum. However, the ability of producing hydrogenase in heterologous expression hosts and the sensitivity of hydrogenases to oxygen and carbon monoxide, etc. have seriously limited the viable macroscale utilization and production of hydrogen from the renewable source. A new technology for the production of up-take hydrogenase is being developed for the utilization of hydrogenase as a hydrogen catalyst. The development of this new technology integrates knowledge of structural biology, molecular biology, and principles of metabolic engineering to produce and engineer a stable hydrogenase as a hydrogen bioelectrocatalyst. It contributes to the critical issues of “expensive noble metal catalysts (i.e., platinum) and their limited reserves threatening the long-term sustainability of a hydrogen economy”. It also provides a model to “design natural materials and enzyme catalyst” for “efficient and cost-effective technologies” for a clean and sustainable energy in 21st century. This new technology includes 3 major components. The first component is the synthetic operons, which carry hydrogenase maturation pathways of Ralstonia eutropha. These synthetic operons are engineered to produce RH hydrogenase in the Escherichia coli strains based on our current molecular and genetic information of hydrogenase maturation mechanisms and pathways of R. eutropha. It presents the first example of producing hydrogenase in the conventional expression host using synthetic biology principles and tool kits. For the high-yield production of the hydrogenase, protein degradation pathways are altered to prevent hydrogenase degradation. This part of the new technology provides a frame work for the design of hydrogenase production pathways for desirable bioengineering purposes. The results of this work are significantly beneficial to research in the areas of enzyme fuel cells, bioelectrocatalyst production, and biohydrogen production as well as basic research in hydrogenase structure biology. The second component of the new technology includes the stable hydrogenase with the improved electrochemical and catalytic properties. With the guidance of the current information on [NiFe] hydrogenase structure, hydrogenase mutants and mutant libraries are generated using protein engineering approaches. The resulting mutants are screened for better hydrogenase stability and catalytic activities. This part of the research results in the identification of new hydrogenase mutants with improved catalytic properties, which can be used for the future studies on enzyme full cells and the catalytic mechanism of hydrogenase. The third component is the optimized production of the selected hydrogenase mutant using current fermentation and metabolic engineering strategies. Metabolic burdens and biomass is balanced using different induction conditions for the optimum production of the engineered hydrogenase in genetically engineered E. coli strains. The success of this work presents a good example of the application of modern fermentation technologies in bioelectrocatalyst production.
- Research Organization:
- Univ. of Hawaii, Honolulu, HI (United States)
- Sponsoring Organization:
- USDOE Office of Hydrogen, Fuel Cells, and Infrastructure Technologies Program (EE-2H)
- DOE Contract Number:
- FG02-06ER15770
- OSTI ID:
- 975052
- Report Number(s):
- 2
- Country of Publication:
- United States
- Language:
- English
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