Expressing the Thermoanaerobacterium saccharolyticum pforA in engineered Clostridium thermocellum improves ethanol production
| Autor: | Daniel G. Olson, Paul P. Lin, Marybeth Maloney, Liang Tian, Shuen Hon, Lee R. Lynd, Evert K. Holwerda, Robert S. Worthen, Jingxuan Cui |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
lcsh:Biotechnology 030106 microbiology Cellobiose Management Monitoring Policy and Law Applied Microbiology and Biotechnology lcsh:Fuel Clostridium thermocellum Metabolic engineering Consolidated bioprocessing 03 medical and health sciences chemistry.chemical_compound lcsh:TP315-360 lcsh:TP248.13-248.65 Ethanol fuel Ferredoxin Ethanol biology Strain (chemistry) Pyruvate ferredoxin oxidoreductase Renewable Energy Sustainability and the Environment Isobutanol Research biology.organism_classification General Energy chemistry Biochemistry bacteria Thermoanaerobacterium saccharolyticum Biotechnology |
| Zdroj: | Biotechnology for Biofuels Biotechnology for Biofuels, Vol 11, Iss 1, Pp 1-11 (2018) |
| ISSN: | 1754-6834 |
| DOI: | 10.1186/s13068-018-1245-2 |
| Popis: | Background Clostridium thermocellum has been the subject of multiple metabolic engineering strategies to improve its ability to ferment cellulose to ethanol, with varying degrees of success. For ethanol production in C. thermocellum, the conversion of pyruvate to acetyl-CoA is catalyzed primarily by the pyruvate ferredoxin oxidoreductase (PFOR) pathway. Thermoanaerobacterium saccharolyticum, which was previously engineered to produce ethanol of high yield (> 80%) and titer (70 g/L), also uses a pyruvate ferredoxin oxidoreductase, pforA, for ethanol production. Results Here, we introduced the T. saccharolyticum pforA and ferredoxin into C. thermocellum. The introduction of pforA resulted in significant improvements to ethanol yield and titer in C. thermocellum grown on 50 g/L of cellobiose, but only when four other T. saccharolyticum genes (adhA, nfnA, nfnB, and adhEG544D) were also present. T. saccharolyticum ferredoxin did not have any observable impact on ethanol production. The improvement to ethanol production was sustained even when all annotated native C. thermocellum pfor genes were deleted. On high cellulose concentrations, the maximum ethanol titer achieved by this engineered C. thermocellum strain from 100 g/L Avicel was 25 g/L, compared to 22 g/L for the reference strain, LL1319 (adhA(Tsc)-nfnAB(Tsc)-adhEG544D (Tsc)) under similar conditions. In addition, we also observed that deletion of the C. thermocellum pfor4 results in a significant decrease in isobutanol production. Conclusions Here, we demonstrate that the pforA gene can improve ethanol production in C. thermocellum as part of the T. saccharolyticum pyruvate-to-ethanol pathway. In our previous strain, high-yield (~ 75% of theoretical) ethanol production could be achieved with at most 20 g/L substrate. In this strain, high-yield ethanol production can be achieved up to 50 g/L substrate. Furthermore, the introduction of pforA increased the maximum titer by 14%. Electronic supplementary material The online version of this article (10.1186/s13068-018-1245-2) contains supplementary material, which is available to authorized users. |
| Databáze: | OpenAIRE |
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