The gut microbiota is responsible for differential anticancer drug efficacies by modulating the host immune system and the tumor microenvironment. Interestingly, this differential effect is highly strain-specific. For example, certain strains can directly suppress tumor growth and enhance antitumor immunity; however, others do not have such an effect or even promote tumor growth. Identifying effective strains that possess antitumor effects is key for developing live biotherapeutic anticancer products. Here, we found that Lactococcus lactis GEN3013 inhibits tumor growth by regulating tumor angiogenesis and directly inducing cancer cell death. Moreover, L. lactis GEN3013 enhanced the therapeutic effects of oxaliplatin and the PD-1 blockade. Comprehensive immune profiling showed that L. lactis GEN3013 augmented cytotoxic immune cell populations, such as CD4⁺ T cells, CD8⁺ effector T cells, and NK cells in the tumor microenvironment. Our results indicate that L. lactis GEN3013 is a promising candidate for potentiating cancer treatment in combination with current standard therapy.

Microbiome-derived metabolites have emerged as key mediators of the gut–brain axis, influencing cognitive function and neuroprotection. This study investigated whether Lactobacillus delbrueckii subsp. lactis CKDB001 alleviates scopolamine-induced memory impairment through metabolic modulation, and how its effects compare with those of donepezil. ICR mice were administered CKDB001 or donepezil for 4–5 weeks and evaluated through behavioral, microbiome, metabolomic, and molecular analyses. CKDB001 significantly improved spatial working memory in a dose-dependent manner, with the high-dose group showing improvements comparable to those of the donepezil-treated group, while passive avoidance showed a non-significant but positive trend. Both CKDB001 and donepezil modulated gut microbial composition, leading to a partial divergence from the scopolamine-disrupted community structure, with CKDB001 inducing dose-dependent intestinal colonization. Metabolomic profiling revealed that both treatments increased tryptophan-derived indole metabolites and altered lipid and short-chain fatty acid metabolite profiles, although these effects were more pronounced in CKDB001-treated mice. At the molecular level, both CKDB001 and donepezil reduced hippocampal tau phosphorylation, downregulated glycogen synthase kinase-3 (GSK-3) signaling, enhanced intestinal tight-junction proteins, and partially normalized acetylcholinesterase activity, with CKDB001 restoring AChE levels more closely toward the normal control. Together, these findings suggest that CKDB001 mitigates cognitive deficits through coordinated modulation of microbial, metabolic, and neuronal pathways, offering a microbiome-based therapeutic approach that may provide benefits comparable to donepezil with potentially fewer limitations.