Engineering Escherichia coli membrane phospholipid head distribution improves tolerance and production of biorenewables

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2017-11
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Khakbaz, Pouyan
Chen, Yingxi
Lombardo, Jeremy
Yoon, Jong Moon
Shanks, Jacqueline
Klauda, Jeffery B.
Jarboe, Laura B.
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Elsevier Inc.
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Jarboe, Laura
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Chemical and Biological Engineering

The function of the Department of Chemical and Biological Engineering has been to prepare students for the study and application of chemistry in industry. This focus has included preparation for employment in various industries as well as the development, design, and operation of equipment and processes within industry.Through the CBE Department, Iowa State University is nationally recognized for its initiatives in bioinformatics, biomaterials, bioproducts, metabolic/tissue engineering, multiphase computational fluid dynamics, advanced polymeric materials and nanostructured materials.

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The Department of Chemical Engineering was founded in 1913 under the Department of Physics and Illuminating Engineering. From 1915 to 1931 it was jointly administered by the Divisions of Industrial Science and Engineering, and from 1931 onward it has been under the Division/College of Engineering. In 1928 it merged with Mining Engineering, and from 1973–1979 it merged with Nuclear Engineering. It became Chemical and Biological Engineering in 2005.

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1913 - present

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  • Department of Chemical Engineering (1913–1928)
  • Department of Chemical and Mining Engineering (1928–1957)
  • Department of Chemical Engineering (1957–1973, 1979–2005)
    • Department of Chemical and Biological Engineering (2005–present)

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Microbiology
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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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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NSF Engineering Research Center for Biorenewable Chemicals
Founded in 2008 with more than $44M in federal, industry, and Iowa State University funding, CBiRC works in tandem with Iowa and the nation’s growing biosciences sector. CBiRC’s goal is to lead the transformation of the chemical industry toward a future where chemicals derived from biomass resources will lead to the production of new bioproducts to meet evolving societal needs.
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Economically competitive microbial production of biorenewable fuels and chemicals is often impeded by toxicity of the product to the microbe. Membrane damage is often identified as a major mechanism of this toxicity. Prior efforts to strengthen the microbial membrane by changing the phospholipid distribution have largely focused on the fatty acid tails. Herein, a novel strategy of phospholipid head engineering is demonstrated in Escherichia coli. Specifically, increasing the expression of phosphatidylserine synthase (+pssA) was found to significantly increase both the tolerance and production of octanoic acid, a representative membrane-damaging solvent. Tolerance of other industrially-relevant inhibitors, such as furfural, acetate, toluene, ethanol and low pH was also increased. In addition to the increase in the relative abundance of the phosphoethanolamine (PE) head group in the +pssA strain, there were also changes in the fatty acid tail composition, resulting in an increase in average length, percent unsaturation and decreased abundance of cyclic rings. This +pssA strain had significant changes in: membrane integrity, surface potential, electrochemical potential and hydrophobicity; sensitivity to intracellular acidification; and distribution of the phospholipid tails, including an increase in average length and percent unsaturation and decreased abundance of cyclic rings. Molecular dynamics simulations demonstrated that the +PE membrane had increased resistance to penetration of ethanol into the hydrophobic core and also the membrane thickness. Further hybrid models in which only the head group distribution or fatty acid tail distribution was altered showed that the increase in PE content is responsible for the increase in bilayer thickness, but the increased hydrophobic core thickness is due to altered distribution of both the head groups and fatty acid tails. This work demonstrates the importance of consideration of the membrane head groups, as well as a modeling approach, in membrane engineering efforts.
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This is a manuscript of an article published as Tan, Zaigao, Pouyan Khakbaz, Yingxi Chen, Jeremy Lombardo, Jong Moon Yoon, Jacqueline V. Shanks, Jeffery B. Klauda, and Laura R. Jarboe. "Engineering Escherichia coli membrane phospholipid head distribution improves tolerance and production of biorenewables." Metabolic Engineering 44 (2017): 1-12. DOI: 10.1016/j.ymben.2017.08.006. Copyright 2017 International Metabolic Engineering Society. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission.
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