L(-)-carnitine production using a recombinant Escherichia coli strain

Area of Science:

• Biotechnology
• Biocatalysis
• Metabolic Engineering

Background:

• L(-)-carnitine is an essential biomolecule with various physiological roles.
• Efficient and cost-effective production methods are crucial for meeting demand.
• Previous methods for L(-)-carnitine production faced limitations in yield and productivity.

Purpose of the Study:

• To optimize the biotransformation process for L(-)-carnitine production using recombinant Escherichia coli.
• To investigate the use of crotonobetaine and D(+)-carnitine as substrates.
• To enhance the overall productivity and reusability of the biocatalyst.

Main Methods:

• Utilized a recombinant Escherichia coli strain (pT7-5KE32) for L(-)-carnitine biotransformation.
• Employed a resting cell system, optimizing growth conditions (anaerobic, 37°C) and inducer presence.
• Determined optimal biotransformation parameters including cell density, substrate concentration, and aeration.

Main Results:

• Crotonobetaine was identified as the superior substrate compared to D(+)-carnitine.
• Optimal biotransformation achieved with resting cells under aerobic conditions (4 g/L biomass, 100 mM substrate).
• Achieved a 70% L(-)-carnitine yield in 1 hour, with a productivity of 11.3 g/L/h.
• Resting cells demonstrated reusability up to eight times with sustained yields >50%.

Conclusions:

• The optimized resting cell biotransformation system significantly enhances L(-)-carnitine production efficiency.
• This method offers a more sustainable and cost-effective approach compared to previous studies.
• The improved productivity and cell reusability present a scalable solution for L(-)-carnitine manufacturing.