The role of the gut microbiota in colorectal cancer (CRC) development has garnered attention, highlighting probiotics as potential adjuncts in CRC prevention and treatment. In recent years, probiotics and their derivatives have demonstrated mechanisms that may contribute to anticancer properties. This study investigates the cytotoxic effects of Bifidobacterium bifidum KCTC 3357, Lacticaseibacillus rhamnosus KCTC 5033, Limosilactobacillus reuteri VA 103, Bacillus galactosidilyticus VA 107, and Lactococcus taiwanensis VE101 on CT-26 mouse colon carcinoma cells using live cells, heat-killed cells (paraprobiotics), and cell-free supernatants (CFS, postbiotics) through an MTT assay. The results indicate that live bacterial strains, such as KCTC 3357, VA 103, and VA 107, promoted CT-26 cell viability, while heat-killed cells and CFS exhibited dose-dependent cytotoxicity. Inactivated forms of KCTC 3357 and VE 101, as well as CFS at 10 mg/mL concentration of KCTC 5033, VA 103, and VE 101, showed the strongest antiproliferative effects. These findings suggest that non-viable probiotic derivatives, such as paraprobiotics and postbiotics, offer promising therapeutic potential for CRC, providing a safer and more stable alternative to live probiotics. However, further research is required to explore their mechanisms of action, in vivo efficacy, and potential clinical applications.

Probiotics, enzymes, organic acids, oligosaccharides, antioxidants, and other functional materials are actively being explored as alternatives to antibiotics. Probiotics include live beneficial microorganisms that colonize the intestinal tract and competitively inhibit attachment and growth of harmful microbes. Probiotics also increase feed efficiency by assisting in nutrient absorption and digestion. The current study was conducted in order to evaluate the effect of a new probiotic, CS-A, as a dietary supplement of a fermented product on growth performance, feed intake, and feed conversion efficiency in broiler chickens, and to evaluate its value as an alternative for antibiotics used as a feed additive. Antibacterial and anti-inflammatory effects of CS-A were investigated in vitro and the in vivo effects of a constant concentration of supplemented CS-A on growth rate and feed efficiency were evaluated. In addition, the safety of CS-A was assessed by examination of common symptoms and mortality. Determination of minimal inhibitory concentration revealed an excellent antibacterial effect of CS-A. Cytotoxicity was low and anti-inflammatory effects were achieved at the effective concentration of CS-A. Supplementation with 0.1% CS-A resulted in a feed efficiency score of 1.84 in broilers, compared to 2.00 in the control group. There were no adverse clinical findings, necropsy findings, hematology, and altered serum biochemistry parameters, and no mortality. Thus, it is concluded that CS-A is safe and effective as a feed additive.