Food utility potential of protease obtained from insect-commensal Bacillus subtilis AU-2

Background: Bacillus subtilis AU-2, isolated from the gut of Tribolium castaneum, was used for protease production. The purified protease was evaluated for its potential in food-related applications including meat tenderization, milk coagulation, and the preparation of enzymatic soybean hydrolysates. Enzymatic hydrolysis of soy protein is an effective method for producing protein hydrolysates with optimal techno-functional properties.

Results: This study confirmed that B. subtilis AU-2 is a commensal with T. castaneum, within the insect gut flora. The purified protease obtained from B. subtilis AU-2 exhibited meat tenderization activity and an ability to promote milk coagulation within a 20 min timeframe. Soybean hydrolysate prepared using the protease exhibited a relatively higher degree of hydrolysis (20.1%) than pepsin, trypsin, and papain. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) peptide fragmentation pattern of the enzymatically prepared soy protein hydrolysate revealed the disappearance of ~35 kDa protein bands after 4 h protease treatment. The prepared soy protein hydrolysate showed improved emulsifying capacity (EC) (705 mL g^-1) and exhibited significant 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity (77.89%) and hydroxyl (OH) radical scavenging activity (97.23%).

Conclusions: The protease obtained from the newly isolated B. subtilis AU-2 strain exhibited potential for food-related applications, including meat tenderization, milk clotting, and soybean hydrolysate preparation. Its accessibility opens avenues for utilization in the food processing industry. © 2024 Society of Chemical Industry.