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

Abstract

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:

Wu, Weihua ^[1]; Liu, Fang ^[1]; Singh, Seema ^[2]

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+ Show Author Affiliations

1. Biomass Science &, Conversion Technologies Department, Sandia National Laboratories, Livermore, CA 94550,
2. Biomass Science &, Conversion Technologies Department, Sandia National Laboratories, Livermore, CA 94550,, Joint BioEnergy Institute, Emeryville, CA 94608,, Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN 55108

Publication Date:

Fri Mar 02 00:00:00 EST 2018

Research Org.:

Sandia National Lab. (SNL-CA), Livermore, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1423513

Alternate Identifier(s):

OSTI ID: 1473955

Report Number(s):

SAND-2018-9920J
Journal ID: ISSN 0027-8424

Grant/Contract Number:  

16-0758; AC02-05CH11231; AC04-94AL85000

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 115 Journal Issue: 12; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; lignin valorization; vanillin-inducible promoter; aromatics transporter; autoregulatory; catechol