2.1 Chemicals, plasmids, and culture media
Lactose, galactitol, NADH, NADPH, NAD+, and
NADP+ were purchased from Coolaber Co. Ltd. (Beijing,
China). The five types of WP were obtained from Qianwei Biotech
(Shanghai, China), Miaolingziwei Biotech (Henan, China), Wanbang Biotech
(Henan, China), Gushuo Biotech (Henan, China), and Fengtai Biotech
(Shandong, China). The β -galactosidase with ~1.2
× 105 U was purchased from Weilan Biotech (Shandong,
China). The KOD-Plus-Mutagenesis Kit was purchased from Toyobo Co., Ltd.
(Osaka, Japan). ABclonal MultiF Seamless Assembly was purchased from
ABclonal Technology Co., Ltd. (Wuhan, China). pET-32a was purchased from
Invitrogen (Carlsbad, CA, USA). Ampicillin and
isopropyl-beta-D-thiogalactopyranoside
(IPTG) were purchased from Gen-View Scientific Inc. (El Monte, CA, USA).Escherichia coli DH5α and E. coli BL21 (DE3) were
purchased from Tsingke Biotechnology Co., Ltd. and TransGen Biotech
(Beijing, China), respectively. Primers were synthesized by Ruibiotech
Co., Ltd. (Beijing, China). Phanta®Max Super-Fidelity DNA Polymerase was
purchased from Vazyme Biotech Co., Ltd. (Nanjing, China). Any other
chemicals used in this study were analytical grade and obtained
commercially unless otherwise noted.