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Van Gelder K, Oliveira-Filho ER, Messina CD, Venado RE, Wilker J, Rajasekar S, Ané JM, Amthor JS, Hanson AD. Running the numbers on plant synthetic biology solutions to global problems. Plant Sci 2023; 335:111815. [PMID: 37543223 DOI: 10.1016/j.plantsci.2023.111815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/30/2023] [Accepted: 08/02/2023] [Indexed: 08/07/2023]
Abstract
Synthetic biology and metabolic engineering promise to deliver sustainable solutions to global problems such as phasing out fossil fuels and replacing industrial nitrogen fixation. While this promise is real, scale matters, and so do knock-on effects of implementing solutions. Both scale and knock-on effects can be estimated by 'Fermi calculations' (aka 'back-of-envelope calculations') that use uncontroversial input data plus simple arithmetic to reach rough but reliable conclusions. Here, we illustrate how this is done and how informative it can be using two cases: oilcane (sugarcane engineered to accumulate triglycerides instead of sugar) as a source of bio-jet fuel, and nitrogen fixation by bacteria in mucilage secreted by maize aerial roots. We estimate that oilcane could meet no more than about 1% of today's U.S. jet fuel demand if grown on all current U.S. sugarcane land and that, if cane land were expanded to meet two-thirds of this demand, the fertilizer and refinery requirements would create a large carbon footprint. Conversely, we estimate that nitrogen fixation in aerial-root mucilage could replace up to 10% of the fertilizer nitrogen applied to U.S. maize, that 2% of plant carbon income used for growth would suffice to fuel the fixation, and that this extra carbon consumption would likely reduce grain yield only slightly.
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Affiliation(s)
- Kristen Van Gelder
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | | | - Carlos D Messina
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Rafael E Venado
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jennifer Wilker
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Shanmugam Rajasekar
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jean-Michel Ané
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jeffrey S Amthor
- Center for Ecosystem Science and Society, Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Andrew D Hanson
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA.
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