A Novel Thermal-Activated β-Galactosidase from Bacillus aryabhattai GEL-09 for Lactose Hydrolysis in Milk

Foods

Shuyue Luan¹  Xuguo Duan¹ 

[1] Department of Food Science and Technology, College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China;

关键词: β-galactosidase;    Bacillus aryabhattai;    thermal-activated;    lactose hydrolysis;    milk;   

DOI  :  10.3390/foods11030372

来源: DOAJ

【 摘 要 】

β-Galactosidase has been greatly used in the dairy industry. This study investigated a novel thermostable β-galactosidase (lacZBa) from Bacillus aryabhattai GEL-09 and evaluated the hydrolytic performance of this enzyme. Firstly, the lacZBa-encoding gene was cloned and overexpressed in Escherichia coli BL21(DE3). Phylogenetic analyses revealed that lacZBa belonged to the glycoside hydrolase family 42. Using SDS-PAGE, we determined that the molecular weight of lacZBa was ~75 kDa. Purified lacZBa exhibited a maximum activity at 45 °C, pH 6.0, and could be activated following incubation at 45 °C for several minutes. The half-life of lacZBa at 45 °C and 50 °C was 264 h and 36 h, respectively. While Co²⁺, Mn²⁺, Zn²⁺, Fe²⁺, Mg²⁺, and Ca²⁺ enhanced enzymatic activity, Cu²⁺ and ethylenediaminetetraacetic acid inhibited enzymatic activity. Moreover, lacZBa could hydrolyze lactose and oNPG with K_m values of 85.09 and 14.38 mM. Molecular docking results revealed that lacZBa efficiently recognized and catalyzed lactose. Additionally, the hydrolysis of lactose by lacZBa was studied in lactose solution and commercial milk. Lactose was completely hydrolyzed within 4 h with 8 U/mL of lacZBa at 45 °C. These results suggested that lacZBa identified in this study has potential applications in the dairy industry.

【 授权许可】

Unknown