Maintenance of ATP Homeostasis Triggers Metabolic Shifts in Gas-Fermenting Acetogens.
Cell Syst
; 4(5): 505-515.e5, 2017 05 24.
Article
em En
| MEDLINE
| ID: mdl-28527885
ABSTRACT
Acetogens are promising cell factories for producing fuels and chemicals from waste feedstocks via gas fermentation, but quantitative characterization of carbon, energy, and redox metabolism is required to guide their rational metabolic engineering. Here, we explore acetogen gas fermentation using physiological, metabolomics, and transcriptomics data for Clostridium autoethanogenum steady-state chemostat cultures grown on syngas at various gas-liquid mass transfer rates. We observe that C. autoethanogenum shifts from acetate to ethanol production to maintain ATP homeostasis at higher biomass concentrations but reaches a limit at a molar acetate/ethanol ratio of â¼1. This regulatory mechanism eventually leads to depletion of the intracellular acetyl-CoA pool and collapse of metabolism. We accurately predict growth phenotypes using a genome-scale metabolic model. Modeling revealed that the methylene-THF reductase reaction was ferredoxin reducing. This work provides a reference dataset to advance the understanding and engineering of arguably the first carbon fixation pathway on Earth.
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Base de dados:
MEDLINE
Assunto principal:
Clostridium
/
Ciclo do Carbono
/
Engenharia Metabólica
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article