TY - JOUR
T1 - Membrane engineering via trans unsaturated fatty acids production improves Escherichia coli robustness and production of biorenewables
AU - Tan, Zaigao
AU - Yoon, Jong Moon
AU - Nielsen, David
AU - Shanks, Jacqueline V.
AU - Jarboe, Laura R.
N1 - Funding Information:
This work was supported by the National Science Foundation, United States Engineering Research Center for Biorenewable Chemicals (CBiRC), NSF Award no. EEC-0813570 . David Nielsen is supported in part by NSF Award no. CBET-1511637 . The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We thank Dr. Zengyi Shao for providing the Pseudomonas strain. We thank ISU Flow Cytometry Facility for help with SYTOX Green cells analysis and ISU W.M. Keck Metabolomics Research Laboratory for help with membrane polarization analysis and GC–MS analysis.
Publisher Copyright:
© 2016 International Metabolic Engineering Society.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - 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.
AB - 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.
KW - Carboxylic acids production
KW - Membrane fluidity
KW - Membrane integrity
KW - Tolerance
KW - Trans unsaturated fatty acids (TUFA)
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U2 - 10.1016/j.ymben.2016.02.004
DO - 10.1016/j.ymben.2016.02.004
M3 - Article
C2 - 26875445
AN - SCOPUS:84959318102
SN - 1096-7176
VL - 35
SP - 105
EP - 113
JO - Metabolic Engineering
JF - Metabolic Engineering
ER -