Recombinant gene expression in Escherichia coli cultivation using lactose as inducer

Area of Science:

• Biotechnology
• Molecular Biology
• Microbial Engineering

Background:

• The lac UV5 promoter is a key element for controlling foreign gene expression in recombinant Escherichia coli.
• Optimizing induction strategies is crucial for maximizing heterologous protein yields in bioreactor cultivations.

Purpose of the Study:

• To investigate the efficacy of lactose as an inducer for foreign gene expression in Escherichia coli.
• To determine an optimal induction strategy for high-level production of chicken troponin C (TnC).

Main Methods:

• Recombinant Escherichia coli expressing chicken TnC were cultivated using a feed-forward controlled fed-batch strategy.
• An induction strategy combining pulsed lactose addition and yeast extract supplementation was employed.
• High cell concentrations (22 g l-1 dry cell weight) were achieved before induction.

Main Results:

• A TnC content of 19.5% of total cell protein was achieved.
• The induction strategy involved three lactose pulses (4.7 g g-1 DCW total) and yeast extract addition.
• Residual lactose concentration was identified as a critical factor influencing heterologous protein production.

Conclusions:

• Optimized lactose feeding strategies are essential for efficient heterologous protein production.
• The presented induction method significantly enhances the yield of specific proteins like TnC.
• Understanding the role of residual lactose is key to further improving recombinant protein expression systems.