Butyrate enhances Clostridioides difficile sporulation .

Unlabelled: Short chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as the intestinal barrier, signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including importance in combatting infections caused by pathogens such as . Despite the potential role of SCFAs in mitigating infection, their direct effect on remains unclear. Through a set of experiments, we investigated how SCFAs influence growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of strain 630 in a dose-dependent manner. The presence of butyrate also increased sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with alternative metabolic and related regulatory pathways, such as the carbon catabolite repressor, CcpA. Collectively, these data suggest that butyrate may signal alternative metabolic pathways, thus modifying its growth and virulence to persist in the gut environment.

Importance: Several studies suggest that butyrate may be important in alleviating gut infections, such as reducing inflammation caused by the healthcare-associated . While studies in both animal models and human studies correlate high levels of butyrate with reduced burden, the direct impact of butyrate on remains unclear. Our study demonstrates that butyrate directly influences by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat in a butyrate-directed manner.