Metabolic Engineering of Synechococcus elongatus 7942 for Enhanced Sucrose Biosynthesis

Bo Wang, Cristal Zuniga, Michael Guarnieri, Karsten Zengler, Michael Betenbaugh, Jamey Young

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations


The capability of cyanobacteria to produce sucrose from CO2 and light has a remarkable societal and biotechnological impact since sucrose can serve as a carbon and energy source for a variety of heterotrophic organisms and can be converted into value-added products. However, most metabolic engineering efforts have focused on understanding local pathway alterations that drive sucrose biosynthesis and secretion in cyanobacteria rather than analyzing the global flux re-routing that occurs following induction of sucrose production by salt stress. Here, we investigated global metabolic flux alterations in a sucrose-secreting (cscB-overexpressing) strain relative to its wild-type Synechococcus elongatus 7942 parental strain. We used targeted metabolomics, 13C metabolic flux analysis (MFA), and genome-scale modeling (GSM) as complementary approaches to elucidate differences in cellular resource allocation by quantifying metabolic profiles of three cyanobacterial cultures – wild-type S. elongatus 7942 without salt stress (WT), wild-type with salt stress (WT/NaCl), and the cscB-overexpressing strain with salt stress (cscB/NaCl) – all under photoautotrophic conditions. We quantified the substantial rewiring of metabolic fluxes in WT/NaCl and cscB/NaCl cultures relative to WT and identified a metabolic bottleneck limiting carbon fixation and sucrose biosynthesis. This bottleneck was subsequently mitigated through heterologous overexpression of glyceraldehyde-3-phosphate dehydrogenase in an engineered sucrose-secreting strain. Our study also demonstrates that combining 13C-MFA and GSM is a useful strategy to both extend the coverage of MFA beyond central metabolism and to improve the accuracy of flux predictions provided by GSM.

Original languageAmerican English
Pages (from-to)12-24
Number of pages13
JournalMetabolic Engineering
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 International Metabolic Engineering Society

NREL Publication Number

  • NREL/JA-2700-87582


  • cyanobacteria
  • genome-scale modeling
  • metabolic flux alterations
  • sucrose
  • Synechococcus elongatus 7942


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