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Title: Toward engineering E. coli with an autoregulatory system for lignin valorization

Efficient lignin valorization could add more than 10-fold the value gained from burning it for energy and is critical for economic viability of future biorefineries. However, lignin-derived aromatics from biomass pretreatment are known to be potent fermentation inhibitors in microbial production of fuels and other value-added chemicals. In addition, isopropyl-β-d-1-thiogalactopyranoside and other inducers are routinely added into fermentation broth to induce the expression of pathway enzymes, which further adds to the overall process cost. An autoregulatory system that can diminish the aromatics’ toxicity as well as be substrate-inducible can be the key for successful integration of lignin valorization into future lignocellulosic biorefineries. Toward that goal, in this study an autoregulatory system is demonstrated that alleviates the toxicity issue and eliminates the cost of an external inducer. Specifically, this system is composed of a catechol biosynthesis pathway coexpressed with an active aromatic transporter CouP under induction by a vanillin self-inducible promoter, ADH7, to effectively convert the lignin-derived aromatics into value-added chemicals using Escherichia coli as a host. The constructed autoregulatory system can efficiently transport vanillin across the cell membrane and convert it to catechol. Compared with the system without CouP expression, the expression of catechol biosynthesis pathway with transporter CouP significantlymore » improved the catechol yields about 30% and 40% under promoter pTrc and ADH7, respectively. Furthermore, this study demonstrated an aromatic-induced autoregulatory system that enabled conversion of lignin-derived aromatics into catechol without the addition of any costly, external inducers, providing a promising and economically viable route for lignin valorization.« less
Authors:
 [1] ;  [1] ;  [2]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of Minnesota, St. Paul, MN (United States)
Publication Date:
Report Number(s):
SAND-2018-9920J
Journal ID: ISSN 0027-8424; 667755
Grant/Contract Number:
AC04-94AL85000; 16-0758; AC02-05CH11231
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 115; Journal Issue: 12; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; lignin valorization; vanillin-inducible promoter; aromatics transporter; autoregulatory; catechol
OSTI Identifier:
1423513
Alternate Identifier(s):
OSTI ID: 1473955

Wu, Weihua, Liu, Fang, and Singh, Seema. Toward engineering E. coli with an autoregulatory system for lignin valorization. United States: N. p., Web. doi:10.1073/pnas.1720129115.
Wu, Weihua, Liu, Fang, & Singh, Seema. Toward engineering E. coli with an autoregulatory system for lignin valorization. United States. doi:10.1073/pnas.1720129115.
Wu, Weihua, Liu, Fang, and Singh, Seema. 2018. "Toward engineering E. coli with an autoregulatory system for lignin valorization". United States. doi:10.1073/pnas.1720129115.
@article{osti_1423513,
title = {Toward engineering E. coli with an autoregulatory system for lignin valorization},
author = {Wu, Weihua and Liu, Fang and Singh, Seema},
abstractNote = {Efficient lignin valorization could add more than 10-fold the value gained from burning it for energy and is critical for economic viability of future biorefineries. However, lignin-derived aromatics from biomass pretreatment are known to be potent fermentation inhibitors in microbial production of fuels and other value-added chemicals. In addition, isopropyl-β-d-1-thiogalactopyranoside and other inducers are routinely added into fermentation broth to induce the expression of pathway enzymes, which further adds to the overall process cost. An autoregulatory system that can diminish the aromatics’ toxicity as well as be substrate-inducible can be the key for successful integration of lignin valorization into future lignocellulosic biorefineries. Toward that goal, in this study an autoregulatory system is demonstrated that alleviates the toxicity issue and eliminates the cost of an external inducer. Specifically, this system is composed of a catechol biosynthesis pathway coexpressed with an active aromatic transporter CouP under induction by a vanillin self-inducible promoter, ADH7, to effectively convert the lignin-derived aromatics into value-added chemicals using Escherichia coli as a host. The constructed autoregulatory system can efficiently transport vanillin across the cell membrane and convert it to catechol. Compared with the system without CouP expression, the expression of catechol biosynthesis pathway with transporter CouP significantly improved the catechol yields about 30% and 40% under promoter pTrc and ADH7, respectively. Furthermore, this study demonstrated an aromatic-induced autoregulatory system that enabled conversion of lignin-derived aromatics into catechol without the addition of any costly, external inducers, providing a promising and economically viable route for lignin valorization.},
doi = {10.1073/pnas.1720129115},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 12,
volume = 115,
place = {United States},
year = {2018},
month = {3}
}

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