Lactobacillus paracasei R3 Alleviates Tumor Progression in Mice with Colorectal Cancer.

Lactobacillus paracasei (L. paracasei), a common probiotic lactobacillus, has important functions in the food industry and human health. However, different strains of L. paracasei inevitably show differences in activity and colonization resistance, leading to differentiation in their functions, as well as their physical or chemical properties. The purpose of this study was to evaluate the characteristics of L. paracasei R3 (L.p R3) isolated from healthy human feces and determine whether the criteria for edible probiotics is met. The hemolysis type, biofilm-forming ability, antibiotic susceptibility, toxicity, and effective activity of L.p R3 were determined by establishing its probiotic activity traits in vitro and in vivo. The results showed that L.p R3 had a moderate biofilm formation ability, was sensitive to 11 antibiotics, was resistant to eight antibiotics, and was not hemolytic. The culture characteristics, morphology, and biochemical responses of the strain were consistent with the seed batch characteristics. In toxicity assays, L.p R3-fed mice showed no abnormalities in body weight, growth, or various organs. Additionally, L.p R3 was found to be effective in the prevention and treatment of colorectal cancer. In conclusion, our results revealed that L.p R3 has potential value as an edible probiotic without toxic side effects and alleviated the tumor progression of colorectal cancer in mice.