Related Experiment Video
Updated: Jul 5, 2026
05:30
Methanol Independent Expression by Pichia Pastoris Employing De-repression Technologies
Published on: January 23, 2019
Rewiring a methanol-responsive regulatory system improves glucose-methanol co-utilization in Eubacterium limosum
Jiyun Bae1, Hyunwoo Jung2, Seulgi Kang1
1Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.
Journal of Biological Engineering
|July 4, 2026
Summary
Researchers uncovered a dual regulatory circuit in Eubacterium limosum that controls methanol use. Rewiring this system enhances glucose-methanol co-utilization, boosting growth and product formation in bioprocesses.
Area of Science:
- Microbial metabolism and bioproduction
- Synthetic biology and metabolic engineering
- Gene regulation in prokaryotes
Background:
- Methanol is a key C1 feedstock for sustainable bioproduction.
- Mixotrophic co-utilization of methanol with other substrates can enhance product formation.
- Sequential substrate utilization and delayed methanol assimilation are common challenges in mixotrophy.
Purpose of the Study:
- To elucidate the regulatory mechanism of methanol utilization in the methylotrophic acetogen Eubacterium limosum.
- To determine if engineering this regulatory system can improve methanol co-utilization.
- To understand the interplay between methanol-responsive activation and carbon catabolite repression.
Main Methods:
- Identification of the PmtaR promoter and its regulatory elements.
- Characterization of the AraC-type regulator MtaR and its role in promoter activation.
- Analysis of catabolite repression mediated by CcpA via a catabolite-responsive element (cre).
- Engineering of mta expression using a modified promoter to relieve repression.
Main Results:
- A dual-layer regulatory circuit at PmtaR integrates methanol-responsive activation and carbon catabolite repression.
- MtaR and an upstream activation region drive PmtaR activation, while a cre site mediates CcpA repression.
- This circuit explains sequential glucose and methanol utilization in E. limosum.
- Rewiring mta expression with a cre-free promoter enhanced glucose-methanol co-utilization, increasing growth, substrate uptake, and product formation by up to 3-fold.
- Metabolic analysis revealed a shift towards butyrate production.
Conclusions:
- A novel dual regulatory mechanism governs methanol utilization in E. limosum, integrating specific activation with global repression.
- This mechanism explains sequential substrate use in mixotrophic fermentation.
- Engineering this regulatory circuit offers a strategy to improve methanol co-utilization and product yields in acetogenic bioprocesses.
Related Concept Videos
01:22Bioreactor Controls-III
Strain improvement is a foundational strategy in industrial microbiology aimed at maximizing microbial productivity, particularly because natural isolates typically yield commercially valuable products in very low concentrations. Although optimizing the culture medium and environmental conditions can improve yields, these adjustments are inherently limited by the organism’s genetic potential. As a result, the focus shifts toward genetic modifications to enhance biosynthetic capacity. The...
01:24Other Glycolytic Pathways
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...
01:27Production of Alcohol
Continuous fermentation is a key strategy in industrial ethanol production, particularly when efficiency, scalability, and high yields are essential. This approach allows for uninterrupted operation and optimized resource utilization. The primary feedstock, corn starch, undergoes enzymatic hydrolysis facilitated by α-amylase and glucoamylase. These enzymes break down the starch into fermentable sugars such as glucose, which are readily assimilated by fermentative microorganisms.Fermentation...
01:26Microbes and Methanogenesis
Methanogenesis is a critical microbial process in anaerobic ecosystems responsible for the biological production of methane, a potent greenhouse gas and valuable biofuel. This metabolic pathway is primarily facilitated by methanogenic archaea, which thrive in anoxic environments such as wetlands, sediments, and animal gastrointestinal tracts. The absence of oxygen in these habitats prevents aerobic respiration, thereby favoring alternative biochemical pathways for organic matter degradation.In...
01:25Inducible Operons: lac Operon
The lac operon in Escherichia coli is a model for understanding inducible gene regulation and metabolic flexibility. It integrates local control by lactose and global regulation through catabolite repression, enabling E. coli to preferentially metabolize glucose when available and switch to lactose utilization when glucose is scarce.Structure and Function of the lac OperonThe lac operon contains three structural genes: lacZ (β-galactosidase), lacY (lactose permease), and lacA (thiogalactoside...
01:23Microbial Fermentation
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...