Lacticaseibacillus rhamnosus M9 inhibits the growth of breast tumors in mice by regulating gut microbiota, immunity and blood metabolites

A total of 36 mice were randomized into three groups (n=12 per group), namely, 1) Con group (without tumor xenograft) p; 2) Mol group (tumor xenograft group), and 3) Pro group (tumor xenograft with oral gavage of probiotics). Probiotics was administered to mice from probiotic group by daily oral gavage with 4x10^9 CFU/day Probio-M9 for 7 days prior to tumor inoculation, and the two nonprobiotic recipient groups were given an equal amount of normal saline. Tumor transplantation was conducted at day 7. After tumor transplantation (day 7), the probiotic group continue received the Probio-M9, while the control and the tumor xenograft groups were administered equal volume of sterilized saline daily by oral gavage. Tumor size was measured by vernier calipers at days 23, 25, 27, 29, 31 and 33. Mouse feces,serum, and tumor tissue were sampled at day 33.