Ethanol tolerance in engineered strains of Clostridium thermocellum
Abstract Clostridium thermocellum is a natively cellulolytic bacterium that is promising candidate for cellulosic biofuel production, and can produce ethanol at high yields (75–80% of theoretical) but the ethanol titers produced thus far are too low for commercial application. In several strains of...
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| Format: | Article |
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BMC
2023-09-01
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| Series: | Biotechnology for Biofuels and Bioproducts |
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| Online Access: | https://doi.org/10.1186/s13068-023-02379-z |
| _version_ | 1827635251292143616 |
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| author | Daniel G. Olson Marybeth I. Maloney Anthony A. Lanahan Nicholas D. Cervenka Ying Xia Angel Pech-Canul Shuen Hon Liang Tian Samantha J. Ziegler Yannick J. Bomble Lee R. Lynd |
| author_facet | Daniel G. Olson Marybeth I. Maloney Anthony A. Lanahan Nicholas D. Cervenka Ying Xia Angel Pech-Canul Shuen Hon Liang Tian Samantha J. Ziegler Yannick J. Bomble Lee R. Lynd |
| author_sort | Daniel G. Olson |
| collection | DOAJ |
| description | Abstract Clostridium thermocellum is a natively cellulolytic bacterium that is promising candidate for cellulosic biofuel production, and can produce ethanol at high yields (75–80% of theoretical) but the ethanol titers produced thus far are too low for commercial application. In several strains of C. thermocellum engineered for increased ethanol yield, ethanol titer seems to be limited by ethanol tolerance. Previous work to improve ethanol tolerance has focused on the WT organism. In this work, we focused on understanding ethanol tolerance in several engineered strains of C. thermocellum. We observed a tradeoff between ethanol tolerance and production. Adaptation for increased ethanol tolerance decreases ethanol production. Second, we observed a consistent genetic response to ethanol stress involving mutations at the AdhE locus. These mutations typically reduced NADH-linked ADH activity. About half of the ethanol tolerance phenotype could be attributed to the elimination of NADH-linked activity based on a targeted deletion of adhE. Finally, we observed that rich growth medium increases ethanol tolerance, but this effect is eliminated in an adhE deletion strain. Together, these suggest that ethanol inhibits growth and metabolism via a redox-imbalance mechanism. The improved understanding of mechanisms of ethanol tolerance described here lays a foundation for developing strains of C. thermocellum with improved ethanol production. |
| first_indexed | 2024-03-09T15:24:18Z |
| format | Article |
| id | doaj.art-5aaf12444d4d4f58bc14ee1dfb715d71 |
| institution | Directory Open Access Journal |
| issn | 2731-3654 |
| language | English |
| last_indexed | 2024-03-09T15:24:18Z |
| publishDate | 2023-09-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels and Bioproducts |
| spelling | doaj.art-5aaf12444d4d4f58bc14ee1dfb715d712023-11-26T12:36:02ZengBMCBiotechnology for Biofuels and Bioproducts2731-36542023-09-0116111510.1186/s13068-023-02379-zEthanol tolerance in engineered strains of Clostridium thermocellumDaniel G. Olson0Marybeth I. Maloney1Anthony A. Lanahan2Nicholas D. Cervenka3Ying Xia4Angel Pech-Canul5Shuen Hon6Liang Tian7Samantha J. Ziegler8Yannick J. Bomble9Lee R. Lynd10Thayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeThayer School of Engineering at Dartmouth CollegeCenter for Bioenergy Innovation, Oak Ridge National LaboratoryCenter for Bioenergy Innovation, Oak Ridge National LaboratoryThayer School of Engineering at Dartmouth CollegeAbstract Clostridium thermocellum is a natively cellulolytic bacterium that is promising candidate for cellulosic biofuel production, and can produce ethanol at high yields (75–80% of theoretical) but the ethanol titers produced thus far are too low for commercial application. In several strains of C. thermocellum engineered for increased ethanol yield, ethanol titer seems to be limited by ethanol tolerance. Previous work to improve ethanol tolerance has focused on the WT organism. In this work, we focused on understanding ethanol tolerance in several engineered strains of C. thermocellum. We observed a tradeoff between ethanol tolerance and production. Adaptation for increased ethanol tolerance decreases ethanol production. Second, we observed a consistent genetic response to ethanol stress involving mutations at the AdhE locus. These mutations typically reduced NADH-linked ADH activity. About half of the ethanol tolerance phenotype could be attributed to the elimination of NADH-linked activity based on a targeted deletion of adhE. Finally, we observed that rich growth medium increases ethanol tolerance, but this effect is eliminated in an adhE deletion strain. Together, these suggest that ethanol inhibits growth and metabolism via a redox-imbalance mechanism. The improved understanding of mechanisms of ethanol tolerance described here lays a foundation for developing strains of C. thermocellum with improved ethanol production.https://doi.org/10.1186/s13068-023-02379-zWhole genome sequencingNext-generation sequencingToleranceBiofuelHungateiclostridium thermocellumRuminiclostridium thermocellum |
| spellingShingle | Daniel G. Olson Marybeth I. Maloney Anthony A. Lanahan Nicholas D. Cervenka Ying Xia Angel Pech-Canul Shuen Hon Liang Tian Samantha J. Ziegler Yannick J. Bomble Lee R. Lynd Ethanol tolerance in engineered strains of Clostridium thermocellum Biotechnology for Biofuels and Bioproducts Whole genome sequencing Next-generation sequencing Tolerance Biofuel Hungateiclostridium thermocellum Ruminiclostridium thermocellum |
| title | Ethanol tolerance in engineered strains of Clostridium thermocellum |
| title_full | Ethanol tolerance in engineered strains of Clostridium thermocellum |
| title_fullStr | Ethanol tolerance in engineered strains of Clostridium thermocellum |
| title_full_unstemmed | Ethanol tolerance in engineered strains of Clostridium thermocellum |
| title_short | Ethanol tolerance in engineered strains of Clostridium thermocellum |
| title_sort | ethanol tolerance in engineered strains of clostridium thermocellum |
| topic | Whole genome sequencing Next-generation sequencing Tolerance Biofuel Hungateiclostridium thermocellum Ruminiclostridium thermocellum |
| url | https://doi.org/10.1186/s13068-023-02379-z |
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