Metabolic Engineering of Acinetobacter baylyi ADP1 for L-Leucine Production

Area of Science:

• Synthetic biology
• Metabolic engineering
• Microbial biotechnology

Background:

• Acinetobacter baylyi ADP1 is a promising chassis for synthetic biology due to its genetic tractability and rapid growth.
• Assessing its potential for natural product biosynthesis is crucial for expanding its applications.
• Engineering microbial hosts for amino acid production is a key area in biotechnology.

Purpose of the Study:

• To engineer Acinetobacter baylyi ADP1 for enhanced l-leucine production.
• To investigate chassis-specific metabolic regulation in ADP1 for biosynthesis.
• To optimize precursor supply and metabolic flux for improved yields.

Main Methods:

• Overexpression of endogenous leuA and ilvBN genes and modification of the leuBCD operon to relieve feedback inhibition.
• Augmentation of the eda gene and disruption of poxB in the Entner-Doudoroff pathway.
• Development of an inducible sRNA-based system to dynamically repress tricarboxylic acid (TCA) cycle genes.

Main Results:

• Increased l-leucine titers from 0.10 to 0.82 g/L by derepressing the native biosynthetic pathway.
• Achieved a final l-leucine titer of 1.16 g/L with a yield of 0.08 g/g glucose by balancing growth and anabolism.
• Demonstrated that overexpression of wild-type genes, not feedback-resistant variants, was sufficient in ADP1.

Conclusions:

• Acinetobacter baylyi ADP1 can be effectively engineered for l-leucine production, showcasing unique regulatory mechanisms compared to other chassis.
• Optimizing precursor availability and managing carbon flux are critical for maximizing production in nonmodel organisms.
• This study provides valuable insights into chassis-specific metabolic engineering strategies for natural product biosynthesis.