Bifidobacterium breve lw01 was isolated by our group previously,33 (link) and was routinely cultured in MRS Broth (BD) plus Raffinose (Amresco) supplement and 0.5% L-cysteine·HCl (Sigma-Aldrich), under anaerobic environment at 37°C. Lactobacillus rhamnosus CGMCC 1.3724 was purchased from the China General Microbiological Culture Collection Center (CGMCC), and was routinely cultured in MRS Broth (BD) plus Raffinose (Amresco) supplement under anaerobic environment at 37°C. Escherichia coli MG1655 strain, purchased from Wuhan Miaoling Bioscience & Technology Co. Ltd, was routinely cultured in Luria-Bertan Broth at 37 °C with vigorous shaking.