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Sustainable citric acid production from CO2 in an engineered cyanobacterium

Zhang, Lifang; Bryan, Samantha J.; Selão, Tiago Toscano

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Authors

Lifang Zhang

Tiago Toscano Selão



Abstract

Citric acid is one of the most widely used organic acids in the world, with applications ranging from acidity regulation in food and beverages to metal chelation in hydrometallurgical processes. Most of its production is currently derived from fermentative processes, using plant-derived carbon feedstocks. While these are currently dominant, there is an increasing need to develop closed-loop production systems that reduce process carbon footprint. In this work, we demonstrate for the first time that an engineered marine cyanobacterium Synechococcus sp. PCC 7002 can be used as a sustainable chassis for the photosynthetic conversion of CO2 to citric acid. Decreased citric acid cycle flux, through the use of a theophylline-responsive riboswitch, was combined with improved flux through citrate synthase and enhanced citric acid excretion, resulting in a significant improvement to citric acid production. While allowing citrate production, this strategy induces a growth defect which can be overcome by glutamate supplementation or by fine-tuning aconitase levels, resulting in an increase in production relative to WT of over 100-fold. This work represents a first step toward sustainable production of a commodity organic acid from CO2.

Citation

Zhang, L., Bryan, S. J., & Selão, T. T. (2022). Sustainable citric acid production from CO2 in an engineered cyanobacterium. Frontiers in Microbiology, 13, Article 973244. https://doi.org/10.3389/fmicb.2022.973244

Journal Article Type Article
Acceptance Date Jul 21, 2022
Online Publication Date Aug 17, 2022
Publication Date Aug 17, 2022
Deposit Date May 3, 2023
Publicly Available Date May 9, 2023
Journal Frontiers in Microbiology
Electronic ISSN 1664-302X
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 13
Article Number 973244
DOI https://doi.org/10.3389/fmicb.2022.973244
Keywords Microbiology, citrate, cyanobacteria, sustainable production, riboswitch, photosynthesis
Public URL https://nottingham-repository.worktribe.com/output/10907674
Publisher URL https://www.frontiersin.org/articles/10.3389/fmicb.2022.973244/full
Additional Information © 2022 Zhang, Bryan and Selão. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms

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