A Two-Layer Gene Circuit for Decoupling Cell Growth from Metabolite Production

Area of Science:

• Synthetic biology
• Metabolic engineering
• Biotechnology

Background:

• Cell growth and metabolite production are often coupled, leading to inefficient bioprocesses.
• Controlling enzymatic pathways dynamically is crucial for optimizing resource allocation in engineered microbes.
• Mixed-substrate utilization presents challenges for selective and efficient bioproduction.

Purpose of the Study:

• To design and implement a synthetic gene circuit for decoupling cell growth from metabolite production in Escherichia coli.
• To develop autonomous regulatory modules capable of sensing nutrient and substrate levels.
• To engineer controllers for selective substrate utilization and dynamic pathway activation.

Main Methods:

• Construction of a two-layer synthetic gene circuit integrating nutrient and substrate sensing modules.
• Development of controllers with specific sensing capabilities for hydroxycinnamic acid and oleic acid, alongside a glucose sensor.
• Cultivation and analysis of engineered Escherichia coli strains under controlled conditions.

Main Results:

• The hydroxycinnamic acid controller improved growth rate 2-fold and productivity 5-fold, while reducing metabolic stress 2-fold.
• The oleic acid controller increased growth rate 1.3-fold and productivity 2.4-fold, with a 2-fold reduction in metabolic stress.
• Engineered E. coli demonstrated selective substrate utilization and controlled metabolic resource allocation.

Conclusions:

• Synthetic gene circuits can effectively decouple cell growth from metabolite production, enhancing bioprocess efficiency.
• Autonomous regulatory systems offer a powerful strategy for optimizing microbial factories and improving economic viability.
• These findings pave the way for more sustainable and cost-effective bio-based production methods.