Hdrives metabolic rearrangements in gas-fermenting

Valgepea, Kaspar, de Souza Pinto Lemgruber, Renato, Abdalla, Tanus, Binos, Steve, Takemori, Nobuaki, Takemori, Ayako, Tanaka, Yuki, Tappel, Ryan, Köpke, Michael, Simpson, Séan Dennis, Nielsen, Lars Keld and Marcellin, Esteban (2018) Hdrives metabolic rearrangements in gas-fermenting. Biotechnology for biofuels, 11 1: 55. doi:10.1186/s13068-018-1052-9

Author Valgepea, Kaspar
de Souza Pinto Lemgruber, Renato
Abdalla, Tanus
Binos, Steve
Takemori, Nobuaki
Takemori, Ayako
Tanaka, Yuki
Tappel, Ryan
Köpke, Michael
Simpson, Séan Dennis
Nielsen, Lars Keld
Marcellin, Esteban
Title Hdrives metabolic rearrangements in gas-fermenting
Journal name Biotechnology for biofuels   Check publisher's open access policy
ISSN 1754-6834
Publication date 2018-03-01
Sub-type Article (original research)
DOI 10.1186/s13068-018-1052-9
Open Access Status DOI
Volume 11
Issue 1
Start page 55
Publisher BioMed Central Ltd.
Language eng
Subject 1305 Biotechnology
2402 Applied Microbiology and Biotechnology
2105 Renewable Energy, Sustainability and the Environment
2100 Energy
2308 Management, Monitoring, Policy and Law
Abstract The global demand for affordable carbon has never been stronger, and there is an imperative in many industrial processes to use waste streams to make products. Gas-fermenting acetogens offer a potential solution and several commercial gas fermentation plants are currently under construction. As energy limits acetogen metabolism, supply of Hshould diminish substrate loss to COand facilitate production of reduced and energy-intensive products. However, the effects of Hsupply on CO-grown acetogens have yet to be experimentally quantified under controlled growth conditions.

Here, we quantify the effects of Hsupplementation by comparing growth on CO, syngas, and a high-HCO gas mix using chemostat cultures of. Cultures were characterised at the molecular level using metabolomics, proteomics, gas analysis, and a genome-scale metabolic model. CO-limited chemostats operated at two steady-state biomass concentrations facilitated co-utilisation of CO and H. We show that Hsupply strongly impacts carbon distribution with a fourfold reduction in substrate loss as CO(61% vs. 17%) and a proportional increase of flux to ethanol (15% vs. 61%). Notably, Hsupplementation lowers the molar acetate/ethanol ratio by fivefold. At the molecular level, quantitative proteome analysis showed no obvious changes leading to these metabolic rearrangements suggesting the involvement of post-translational regulation. Metabolic modelling showed that Havailability provided reducing power via Hoxidation and saved redox as cells reduced all the COto formate directly using Hin the Wood-Ljungdahl pathway. Modelling further indicated that the methylene-THF reductase reaction was ferredoxin reducing under all conditions. In combination with proteomics, modelling also showed that ethanol was synthesised through the acetaldehyde:ferredoxin oxidoreductase (AOR) activity.

Our quantitative molecular analysis revealed that Hdrives rearrangements at several layers of metabolism and provides novel links between carbon, energy, and redox metabolism advancing our understanding of energy conservation in acetogens. We conclude that Hsupply can substantially increase the efficiency of gas fermentation and thus the feed gas composition can be considered an important factor in developing gas fermentation-based bioprocesses.
Keyword Acetogen
Clostridium autoethanogenum
Gas fermentation
Genome-scale modelling
H2 metabolism
Quantitative proteomics
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID ARC LP140100213
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Pubmed Import
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Created: Wed, 14 Mar 2018, 10:08:16 EST