Colorectal cancer is driven by a sequential cascade of mutations known as the adenoma-carcinoma sequence. Recent studies have revealed that specific bacterial species present in the colonic microbiota can induce mutations and contribute to this malignancy. Specifically, genotoxic colibactin-producing pks+ Escherichia coli strains can induce DNA double strand breaks (DSBs) and promote tumor development in mouse models of colorectal cancer. Here, we investigated the transformation potential of colibactin by using organoids and polarized monolayers derived from primary murine colon epithelial cells and reveal striking phenotypic changes upon short-term infection. This study demonstrates the direct pro-oncogenic potential of pks+ E. coli, as such transformations in vivo could facilitate colitis-associated colorectal carcinogenesis. Overall design: RNAseq of mouse colorectal epithelium (Wnt independent organoids derived from pks+ infected cells and uninfected control organids)