An auto-inducible phosphate-controlled expression system of Bacillus licheniformis

Area of Science:

• Biotechnology
• Molecular Biology
• Microbial Engineering

Background:

• Developing efficient expression systems for heterologous protein production is crucial for industrial applications.
• A cost-effective system requires high-level, long-term gene expression without artificial inducers, especially under substrate-limited growth.

Purpose of the Study:

• To construct and evaluate a novel phosphate-regulated expression system in Bacillus licheniformis.
• To utilize the phytase encoding gene (phyL) promoter for protein overexpression.

Main Methods:

• Construction of a phosphate-regulated expression system using the Bacillus licheniformis phyL promoter.
• Investigating gene expression of heterologous genes (amyE, xynA) under phosphate limitation.
• Assessing the utilization of phytate as an alternative phosphate source.

Main Results:

• The phyL promoter (PphyL) drives strong overexpression of heterologous genes (amyE, xynA) in B. licheniformis under phosphate limitation.
• Bacillus licheniformis can utilize sodium phytate as an alternative phosphate source.
• Low concentrations of sodium phytate (≤ 5 mM) strongly induce gene overexpression under phosphate-limited conditions.

Conclusions:

• The PphyL expression system is strongly auto-induced under phosphate-limited conditions in B. licheniformis.
• This system facilitates target gene overexpression in B. licheniformis.
• The expression system is suitable for fed-batch fermentation processes, enabling efficient protein production.