| Autor: |
Miao Miao, Shusen Li, Shaoqing Yang, Qiaojuan Yan, Zhixuan Xiang, Zhengqiang Jiang |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
Journal of Dairy Science, Vol 107, Iss 9, Pp 6602-6613 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
0022-0302 |
| DOI: |
10.3168/jds.2023-24310 |
| Popis: |
ABSTRACT: Yogurt usually contains 5% to 7% sugar and 3% to 5% lactose. As β-galactosidases can hydrolyze lactose and improve sweetness, they have the potential to produce lactose-free (LF) and no-sugar-added (NSA) yogurt. In this study, the β-galactosidase AoBgal35A from Aspergillus oryzae was engineered by site-saturation mutagenesis. Results of 19 variants of T955 residue showed that the lactose hydrolysis rate of T955R-AoBgal35A was up to 90.7%, which is much higher than the 78.5% of the wild type. Moreover, the optimal pH of T955R-AoBgal35A was shifted from pH 4.5 to pH 5.5, and the optimal temperature decreased from 60°C to 50°C. The mutant T955R-AoBgal35A was successfully expressed in Komagataella pastoris, which produced extracellularly 4,528 U/mL of β-galactosidase activity. The mutant T955R-AoBgal35A was used to produce LF yogurt. The Streptococcus thermophilus count of LF yogurt increased from 7.9 to 9.5 log cfu/g, which is significantly higher than that of the control group (8.9 log cfu/g). The residual lactose content of LF yogurt was 0.13%, meeting the requirements of the national standard in China for the “lactose-free” label ( |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
|
