Characterization of a thermostable protease from Bacillus subtilis BSP strain

Area of Science:

• Biotechnology
• Enzymology
• Microbial Physiology

Background:

• Extracellular thermostable proteases are valuable industrial enzymes.
• Optimization of microbial fermentation is crucial for maximizing enzyme production.
• Bacillus subtilis is a well-established host for protease secretion.

Purpose of the Study:

• To optimize fermentation conditions for increased yield of thermostable protease from a novel Bacillus subtilis BSP strain.
• To purify and characterize the secreted protease.
• To evaluate the potential industrial applications of the enzyme.

Main Methods:

• One variable-at-a-time optimization and statistical surface response methodology (Box Behnken design) were employed.
• Submerged fermentation parameters were adjusted at the shake flask level.
• Protease activity was measured, and the enzyme was purified and characterized biochemically.

Main Results:

• Conventional optimization increased protease yield to 184 U/mL.
• Statistical optimization further enhanced yield to 295 U/mL.
• The 36 kDa protease is a metalloprotease, activated by Ca2+ and Fe2+, and inhibited by EDTA. It demonstrated resistance to organic solvents, surfactants (including SDS), and oxidants (H2O2).

Conclusions:

• The optimized fermentation process significantly improved protease yield.
• The characterized protease exhibits high stability and tolerance to harsh conditions.
• This thermostable metalloprotease has promising potential for detergent and pharmaceutical industries.