Abstract
Intratumor microbiota is a dynamic cancer component that can be carried over by metastatic tumor cells to distal organs. This protocol was developed to genetically label Staphylococcus xylosus and trace the recombinant strain in vivo in the tumor. We optimized the recombination-based gene replacement protocol to insert a GFP-Erythromycin resistant protein (Erm) cassette. The inserted cassette facilitates the tracking of the recombinant strain, allowing a sensitive interrogation of microbial dynamics with high temporal and spatial resolution. For complete details on the use and execution of this protocol, please refer to Fu et al. (2022).