Enhanced expression of cytochrome P450s from lac-based plasmids using lactose as the inducer

Area of Science:

• Molecular Biology
• Biotechnology
• Protein Expression

Background:

• Escherichia coli expression systems for cytochrome P450 rely on the lac repressor system for controlled gene expression.
• Induction typically uses isopropyl-beta-D-thiogalactopyranoside (IPTG), a costly component in E. coli protein production.

Purpose of the Study:

• To investigate the efficacy of lactose as a natural inducer for cytochrome P450 expression in E. coli.
• To compare lactose induction with the standard IPTG induction method in different E. coli expression systems.

Main Methods:

• Examined cytochrome P450 enzyme expression in E. coli using pTrc99A and T7-based PET22b vectors.
• Utilized lactose as an inducer and compared expression levels to those achieved with IPTG.
• Conducted a 20-liter fermentation using lactose for large-scale P450 production.

Main Results:

• Lactose successfully induced active P450 expression in both tested E. coli systems, exceeding IPTG-induced levels.
• Achieved significant yields: 2.4 micromol P450/liter and 2 g total cytochrome P450 in a large-scale fermentation.
• Demonstrated that lactose is a more effective inducer than IPTG for P450 expression.

Conclusions:

• Lactose serves as a superior and cost-effective inducer for cytochrome P450 expression in E. coli.
• This finding supports the broad application of lactose for economical, large-scale heterologous protein production in E. coli.
• Recommends using lactose to reduce costs and improve efficiency in E. coli-based protein expression systems.