A new and efficient phosphate starvation inducible expression system for Lactococcus lactis

Area of Science:

• Microbiology
• Molecular Biology
• Biotechnology

Background:

• Lactococcus lactis is a key host for industrial applications.
• Existing gene expression systems often require specific induction steps or media modifications.
• Development of novel, efficient, and easily controlled expression systems is crucial for optimizing microbial production.

Purpose of the Study:

• To develop and characterize a new inducible gene expression system for Lactococcus lactis.
• To leverage the phosphate starvation-inducible pstF promoter for controlled protein production.
• To compare the efficacy of this novel system with established methods like the nisin-controlled gene expression system (NICE).

Main Methods:

• Construction of an expression system in Lactococcus lactis MG1363 utilizing the pstF promoter.
• Production and quantification of intracellular beta-galactosidase and secreted alpha-amylase.
• Analysis of promoter regions to identify regulatory elements.
• Cultivation in phosphate-depleted media and bioreactor conditions.

Main Results:

• Successfully established a tightly regulated expression system based on the pstF promoter.
• Achieved high expression levels of beta-galactosidase (670 microkat g(-1)) and alpha-amylase (3.6 microkat l(-1)).
• Demonstrated expression levels comparable to the NICE system without requiring induction agents or prior phosphate removal.

Conclusions:

• The developed pstF promoter-based system offers an efficient and convenient alternative for gene expression in Lactococcus lactis.
• This system simplifies bioprocesses by eliminating the need for external inducers and complex media preparation.
• The system operates effectively without the introduction of additional regulatory genes into the host organism.