Comparative analysis of bacterial expression systems for keratinase production

Area of Science:

• Biotechnology
• Enzymology
• Microbial Production

Background:

• Keratinase enzymes are crucial for breaking down keratin.
• Efficient expression systems are needed to maximize keratinase production for industrial applications.

Purpose of the Study:

• To compare the efficacy of Escherichia coli, Bacillus subtilis, and Pichia pastoris as expression systems for Bacillus licheniformis BBE11-1 keratinase.
• To characterize the properties of the recombinant keratinases produced in different hosts.

Main Methods:

• Cloning and expression of the keratinase gene in E. coli (ker E), B. subtilis (ker B), and P. pastoris (ker P).
• Enzyme activity assays under varying pH and temperature conditions.
• Stability tests including metal ion inhibition and hydrogen peroxide treatment.
• Fermentation optimization in a 3-L fermenter.

Main Results:

• All recombinant keratinases exhibited optimal activity at pH 10.
• Pichia pastoris keratinase (ker P) showed enhanced optimal temperature and thermostability.
• Bacillus subtilis keratinase (ker B) achieved a record-high activity of 3,010 U/mL in a 3-L fermenter.
• Enzymes demonstrated significant stability in 1 M hydrogen peroxide and were largely unaffected by most metal ions, except Mn2+.

Conclusions:

• Bacillus subtilis is the superior host for keratinase production, yielding unprecedented activity levels.
• The recombinant keratinases possess favorable properties for industrial use, particularly in textile processing and as feed supplements.