Detection of viable commensal bacteria in murine melanoma tumors by culturomics

Emerging evidence suggests the tumor microbiome at gut-distal sites can modulate tumor immunity and response to cancer immunotherapy. However, detection of commensal bacteria at gut-distal tumor sites is challenging given their low abundance. Here, we present a culturomics approach to facilitate recovery of phylogenetically diverse live commensal bacteria within gut-distal melanoma tumors. We describe steps for media preparation, tissue isolation, tissue homogenization, and host cell lysis. We then detail broth expansion culture followed by agar culture and single-colony 16S rRNA sequencing. For complete details on the use and execution of this protocol, please refer to Bender and McPherson et al. (2023).1