Gut Microbiome of Subcutaneous Tumor Mouse Model Received Intratumor Injection of Engineered Salmonella Treatment

This study investigates the impact of intratumor injection of genetically engineered Salmonella in a colorectal cancer (CRC) subcutaneous (SC) tumor mouse model. We aimed to assess the treatment’s safety and its effect on the gut microbiome. Using a cohort of 50 adult mice divided into treatment (Salmonella) and control (PBS) groups, fecal samples were collected at three timepoints: pre-treatment (T0), 10 days post-treatment (T1), and 20 days post-treatment (T2). The nucleic acid extraction was completed on all of the samples. Through 16S rRNA amplicon sequencing, we observed no Salmonella in any samples, confirming the treatment’s microbiome safety. Alpha diversity revealed significant changes over time within groups, while beta diversity analysis showed clustering primarily by timepoint. Differential abundance analysis highlighted shifts in gut microbiota composition, potentially linked to treatment and cancer progression. These findings offer a preliminary understanding of the microbiome’s response to microbial cancer therapies and underscore the importance of further research to optimize safety and efficacy.