Alkaline proteases and thermostable α-amylase co-produced by Bacillus licheniformis NH1: Characterization and potential application as detergent additive

Alkalophilic Bacillus licheniformis NH1 strain produced at least five major extracellular proteases and a unique amylase as showed by zymography technique. The optimum pH and temperature for the proteolytic activity were 10.0 and 70 °C, respectively, while those of amylolytic activity were 6.5 and 90 °C, respectively. The alkaline proteases and thermostable α-amylase showed extreme stability towards non-ionic and anionic surfactants after pre-incubation for 1 h at 40 °C, and relative stability towards oxidizing agents. Additionally, the crude enzyme showed excellent stability and compatibility with various solid and liquid detergents. Wash performance analysis revealed that the NH1 crude enzyme could effectively remove a variety of stains, such as blood, chocolate and barbecue sauce. Considering its promising properties, B. licheniformis NH1 crude enzyme containing both α-amylase and proteases activities may be considered a potential candidate for future use in detergent processing industries.