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Colon, Brendan

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Colon

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Brendan

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Colon, Brendan

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2015 - 20162

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Author's Publications: search.filters.isAuthorOfPublication.e507bb1e-caaa-499c-9b2b-646884195c97

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    Production of fatty acids in Ralstonia eutropha H16 by engineering β-oxidation and carbon storage
    (PeerJ Inc., 2015) Chen, Janice S.; Colon, Brendan; Dusel, Brendon; Ziesack, Marika; Way, Jeffrey; Torella, Joseph P.
    Ralstonia eutropha H16 is a facultatively autotrophic hydrogen-oxidizing bacterium capable of producing polyhydroxybutyrate (PHB)-based bioplastics. As PHB’s physical properties may be improved by incorporation of medium-chain-length fatty acids (MCFAs), and MCFAs are valuable on their own as fuel and chemical intermediates, we engineered R. eutropha for MCFA production. Expression of UcFatB2, a medium-chain-length-specific acyl-ACP thioesterase, resulted in production of 14 mg/L laurate in wild-type R. eutropha. Total fatty acid production (22 mg/L) could be increased up to 2.5-fold by knocking out PHB synthesis, a major sink for acetyl-CoA, or by knocking out the acyl-CoA ligase fadD3, an entry point for fatty acids into β-oxidation. As ΔfadD3 mutants still consumed laurate, and because the R. eutropha genome is predicted to encode over 50 acyl-CoA ligases, we employed RNA-Seq to identify acyl-CoA ligases upregulated during growth on laurate. Knockouts of the three most highly upregulated acyl-CoA ligases increased fatty acid yield significantly, with one strain (ΔA2794) producing up to 62 mg/L free fatty acid. This study demonstrates that homologous β-oxidation systems can be rationally engineered to enhance fatty acid production, a strategy that may be employed to increase yield for a range of fuels, chemicals, and PHB derivatives in R. eutropha.
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    Water splitting-biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis
    (American Association for the Advancement of Science (AAAS), 2016) Liu, Chong; Colon, Brendan; Ziesack, Marika; Silver, Pamela; Nocera, Daniel
    Artificial photosynthetic systems can store solar energy and chemically reduce CO2. We developed a hybrid water splitting–biosynthetic system based on a biocompatible Earth-abundant inorganic catalyst system to split water into molecular hydrogen and oxygen (H2 and O2) at low driving voltages. When grown in contact with these catalysts, Ralstonia eutropha consumed the produced H2 to synthesize biomass and fuels or chemical products from low CO2 concentration in the presence of O2. This scalable system has a CO2 reduction energy efficiency of ~50% when producing bacterial biomass and liquid fusel alcohols, scrubbing 180 grams of CO2 per kilowatt-hour of electricity. Coupling this hybrid device to existing photovoltaic systems would yield a CO2 reduction energy efficiency of ~10%, exceeding that of natural photosynthetic systems.