Related Experiment Video
Updated: Aug 5, 2025
08:37
Light-Controlled Fermentations for Microbial Chemical and Protein Production
Published on: March 22, 2022
4.1K
Thermodynamic and Kinetic Modeling Directs Pathway Optimization for Isopropanol Production in a Gas-Fermenting
Jonathan Lo1, Chao Wu1, Jonathan R Humphreys1
1Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA.
Msystems
|March 27, 2023
Summary
Engineered Clostridium ljungdahlii bacteria efficiently produce isopropanol from gases. Pathway engineering guided by metabolic models increased production 2.8-fold, enabling sustainable bioproduction from renewable feedstocks.
Area of Science:
- Microbial Engineering
- Synthetic Biology
- Biotechnology
Background:
- Sustainable bioeconomy requires efficient bioproduction from renewable feedstocks.
- Gas-fermenting bacteria offer a platform for valorizing carbon oxides and hydrogen.
- Rational engineering of these microbes is challenged by complex metabolic pathways.
Purpose of the Study:
- To identify key enzymes for enhancing isopropanol production in Clostridium ljungdahlii.
- To develop a predictive metabolic modeling approach for microbial strain optimization.
- To demonstrate iterative pathway engineering for high-yield bioproduct generation.
Main Methods:
- Integrated constraint-based thermodynamic and kinetic modeling with proteomics data.
- Performed in silico thermodynamic optimization and minimal protein requirement analysis.
- Utilized ensemble modeling for robustness analysis and identified flux control sites.
Main Results:
- Identified acetoacetyl-coenzyme A (CoA) transferase (AACT) and acetoacetate decarboxylase (AADC) as key targets for overexpression.
- Achieved a 2.8-fold increase in isopropanol production through iterative pathway construction.
- Produced over 4 g/L isopropanol in mixotrophic conditions and 2.4 g/L using only gases (CO, CO2, H2).
Conclusions:
- Metabolic modeling provides actionable insights for rational strain engineering.
- Directed pathway engineering can significantly enhance bioproduction in gas-fermenting bacteria.
- This approach facilitates iterative microbe redesign for efficient conversion of renewable gaseous feedstocks.
Keywords:
Clostridium ljungdahliiflux control indexgas fermentationisopropanolmetabolic robustness analysisprotein cost analysisthermodynamic analysisMore Related Videos
Related Concept Videos
01:23Microbial Fermentation
114
Fermentation is a crucial anaerobic metabolic process that enables microbes to derive energy from sugar without relying on oxygen or an electron transport chain. This process is fundamental to various biological and industrial applications and is classified based on the metabolic products generated.Role of Pyruvate in FermentationPyruvate and its derivatives serve as key electron acceptors in fermentative pathways. The oxidation of NADH to regenerate NAD+ is essential for the continuation of...
114
01:20Fates of Pyruvate
8.7K
Pyruvate is the end product of glycolysis, where glucose is oxidized to pyruvate, simultaneously reducing NAD+ to NADH. Two molecules of ATP are also produced by substrate-level phosphorylation.
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
8.7K
01:24Other Glycolytic Pathways
84
The pentose phosphate pathway (PPP) operates in parallel with glycolysis, facilitating the metabolism of both pentoses and glucose. This pathway consists of two distinct phases: the oxidative and non-oxidative phases. While it does not directly generate ATP, the intermediates formed during the process can integrate into glycolysis, contributing to cellular energy metabolism when required.Oxidative Phase: NADPH ProductionThe oxidative phase of the pentose phosphate pathway is primarily...
84
01:28Carbon-dioxide Fixation
45
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...
45
01:21Glycolysis: Preparatory Phase
13.8K
In cellular metabolism (the complete breakdown of glucose to extract energy), glycolysis is the first step. Glycolysis takes place in the cytoplasm of both prokaryotic and eukaryotic cells. Glucose enters heterotrophic cells in two ways. One method is through secondary active transport, where the transport takes place against the glucose concentration gradient. The other mechanism uses a group of integral proteins called GLUT proteins, also known as glucose transporter proteins. These...
13.8K
01:24Biosynthesis in Bacteria
43
Biosynthesis in bacteria is a fundamental anabolic process that generates essential macromolecules, including proteins, nucleic acids, lipids, and polysaccharides. These macromolecules are critical for cellular growth, replication, and function. The process is tightly regulated and energetically linked to catabolic pathways to ensure optimal resource utilization.Biosynthetic pathways begin with precursor metabolites such as pyruvate, acetyl-CoA, and glucose-6-phosphate derived from glycolysis,...
43