A novel human Streptomyces strain redresses malignancy by inducing apoptosis and regaining gut homeostasis.

UNLABELLED: Colorectal cancer is among the deadliest malignancies globally. The modern therapies do not lead to ideal outcomes due mostly to drug resistance and recurrence. Previously, we treated cancer patients by ameliorating the gut microbiome and achieved curative effects. We hypothesize that anticancer bacteria might be ubiquitous in the gut but suppressed under certain conditions, pointing to a possibility that an ameliorated gut ecology may help regain the abundance or functions of the hypothetical anticancer bacteria. Here, we show our successful isolation and polyphasic characterization of a gut bacterial strain, CGMCC 17111, which exhibited potent suppressive effects on colorectal cancer. CGMCC 17111 belongs to Streptomyces and is most closely related to the type strain of Streptomyces albidoflavus, DSM 40455T. However, DSM 40455T does not show any appreciable anticancer effects. Genetic, phenotypic, and functional analyses established CGMCC 17111 as representing a novel gut bacterial species with peculiar activities to redress malignancy without eliciting violent inflammatory reactions in the host.

IMPORTANCE: The human gut bacterial strain Streptomyces sp. CGMCC 17111 represents a genetically distinct gut-derived Streptomyces lineage that exhibited antitumor activity in both in vitro and in vivo experimental models. As a resident member of the human gut microbiota, CGMCC 17111 may contribute to host-microbiota interactions that influence tumor-associated biological processes. The findings of this study provide a foundation for future research into gut-derived microbial products and their potential applications in cancer therapy while preserving host physiological homeostasis.