Cited by 168Microbial Metabolic Engineering and BioproductionAlgal biology and biofuel productionMetalloenzymes and iron-sulfur proteins

Redirecting Reductant Flux into Hydrogen Production via Metabolic Engineering of Fermentative Carbon Metabolism in a Cyanobacterium

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McNeely, Kelsey, Xu, Yu, Bennette, Nick, Bryant, Donald A., Dismukes, G. Charles·2010·Applied and Environmental Microbiology

Abstract

Some aquatic microbial oxygenic photoautotrophs (AMOPs) make hydrogen (H 2 ), a carbon-neutral, renewable product derived from water, in low yields during autofermentation (anaerobic metabolism) of intracellular carbohydrates previously stored during aerobic photosynthesis. We have constructed a mutant (the ldhA mutant) of the cyanobacterium Synechococcus sp. strain PCC 7002 lacking the enzyme for the NADH-dependent reduction of pyruvate to d -lactate, the major fermentative reductant sink in this AMOP. Both nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS) metabolomic methods have shown that autofermentation by the ldhA mutant resulted in no d -lactate production and higher concentrations of excreted acetate, alanine, succinate, and hydrogen (up to 5-fold) compared to that by the wild type. The measured intracellular NAD(P)(H) concentrations demonstrated that the NAD(P)H/NAD(P) + ratio increased appreciably during autofermentation in the ldhA strain; we propose this to be the principal source of the observed increase in H 2 production via an NADH-dependent, bidirectional [NiFe] hydrogenase. Despite the elevated NAD(P)H/NAD(P) + ratio, no decrease was found in the rate of anaerobic conversion of stored carbohydrates. The measured energy conversion efficiency (ECE) from biomass (as glucose equivalents) converted to hydrogen in the ldhA mutant is 12%. Together with the unimpaired photoautotrophic growth of the ldhA mutant, these attributes reveal that metabolic engineering is an effective strategy to enhance H 2 production in AMOPs without compromising viability.

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Authors
McNeely, K., Xu, Y., Bennette, N., Bryant, D. A., & Dismukes, G. C.
Affiliations
  • Rutgers, The State University of New Jersey (US)
  • Pennsylvania State University (US)
Venue
Applied and Environmental Microbiology
Published
2010-08
Volume
76
Issue
15
Pages
5032-5038
ISSN
  • 0099-2240 (ISSN-L)
  • 1098-5336
OpenAlex
W2114089350
Cited by
168
References
37
Citations by year
2026: 7 · 2025: 10 · 2024: 5 · 2023: 7 · 2022: 15 · 2021: 3 · 2020: 12 · 2019: 6 · 2018: 9 · 2017: 8 · 2016: 20 · 2015: 13 · 2014: 10 · 2013: 16 · 2012: 7
FWCI
5.60
Type
journal article
Language
en
Open access
Locations
  • Applied and Environmental Microbiology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Multidisciplinary University Research Initiative (FA9550-05-1-0365)
  • Air Force Office of Scientific Research (FA9550-, FA-9550-05-1-0365)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Microbial Metabolic Engineering and Bioproduction
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Algal biology and biofuel production
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Metalloenzymes and iron-sulfur proteins
Keywords
hydrogen production, cyanobacteria, Synechococcus sp. PCC 7002, metabolic engineering, D-lactate, NADH, [NiFe] hydrogenase, acetate, energy conversion efficiency, photoautotrophic growth, fermentative metabolism
MeSH terms
Acetates, Alanine, Bacterial Proteins, Carbohydrate Dehydrogenases, Carbon, Chromatography, Liquid, Genetic Engineering, Hydrogen, Magnetic Resonance Spectroscopy, Oxidation-Reduction, Mass Spectrometry, Pyruvic Acid, Lactic Acid, Succinic Acid, Synechococcus, Metabolic Networks and Pathways, Metabolome

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