Butyrate enhances Clostridioides difficile sporulationin vitro

Abstract

ABSTRACTShort 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 asClostridioides difficile. Despite the potential role of SCFAs in mitigatingC. difficileinfection, their direct effect onC. difficileremains unclear. Through a set ofin vitroexperiments, we investigated how SCFAs influenceC. difficilegrowth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth ofC. difficilestrain 630 in a dose-dependent manner. The presence of butyrate also increasedC. difficilesporulation, 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 relatedC. difficileregulatory pathways, such as the carbon catabolite repressor, CcpA. Collectively, these data suggest that butyrate may signal alternativeC. difficilemetabolic pathways, thus modifying its growth and virulence to persist in the gut environment.IMPORTANCESeveral studies suggest that butyrate may be important in alleviating gut infections, such as reducing inflammation caused by the healthcare-associatedClostridioides difficile. While studies in both animal models and human studies correlate high levels of butyrate with reducedC. difficileburden, the direct impact of butyrate onC. difficileremains unclear. Our study demonstrates that butyrate directly influencesC. difficileby 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 combatC. difficilein a butyrate-directed manner.