Membrane engineering via trans unsaturated fatty acids production improves Escherichia coli robustness and production of biorenewables

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Tan, Zaigao
Yoon, Jong Moon
Nielsen, David R.
Shanks, Jacqueline
Jarboe, Laura
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Bioinformatics and Computational Biology
The Bioinformatics and Computational Biology (BCB) Program at Iowa State University is an interdepartmental graduate major offering outstanding opportunities for graduate study toward the Ph.D. degree in Bioinformatics and Computational Biology. The BCB program involves more than 80 nationally and internationally known faculty—biologists, computer scientists, mathematicians, statisticians, and physicists—who participate in a wide range of collaborative projects.
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Microbiology allows you to learn about the microorganisms that affect us every day and how they interact with their surroundings. Through the program, you will be equipped with the knowledge to work in areas related to agriculture, the environment and medicine.
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Chemical and Biological EngineeringBioinformatics and Computational BiologyMicrobiology
Constructing microbial biocatalysts that produce biorenewables at economically viable yields and titers is often hampered by product toxicity. For production of short chain fatty acids, membrane damage is considered the primary mechanism of toxicity, particularly in regards to membrane integrity. Previous engineering efforts in Escherichia coli to increase membrane integrity, with the goal of increasing fatty acid tolerance and production, have had mixed results. Herein, a novel approach was used to reconstruct the E. coli membrane by enabling production of a novel membrane component. Specifically, trans unsaturated fatty acids (TUFA) were produced and incorporated into the membrane of E. coli MG1655 by expression of cis-trans isomerase (Cti) from Pseudomonas aeruginosa. While the engineered strain was found to have no increase in membrane integrity, a significant decrease in membrane fluidity was observed, meaning that membrane polarization and rigidity were increased by TUFA incorporation. As a result, tolerance to exogenously added octanoic acid and production of octanoic acid were both increased relative to the wild-type strain. This membrane engineering strategy to improve octanoic acid tolerance was found to require fine-tuning of TUFA abundance. Besides improving tolerance and production of carboxylic acids, TUFA production also enabled increased tolerance in E. coli to other bio-products, e.g. alcohols, organic acids, aromatic compounds, a variety of adverse industrial conditions, e.g. low pH, high temperature, and also elevated styrene production, another versatile bio-chemical product. TUFA permitted enhanced growth due to alleviation of bio–product toxicity, demonstrating the general effectiveness of this membrane engineering strategy towards improving strain robustness.
This is a manuscript of an article published as Tan, Zaigao, Jong Moon Yoon, David R. Nielsen, Jacqueline V. Shanks, and Laura R. Jarboe. "Membrane engineering via trans unsaturated fatty acids production improves Escherichia coli robustness and production of biorenewables." Metabolic Engineering 35 (2016): 105-113. DOI: 10.1016/j.ymben.2016.02.004. Copyright 2016 International Metabolic Engineering Society. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission.