Clostridioides difficile Motility in Defined Culture Media and its Response to Nutrients

In recent years, Clostridiodes difficile has caused a sharp increase in hospital-acquired infections. Patients on multiple courses of antibiotics experience a general clearing of normal gut microbiota, leading to dysbiosis and an opportunity for C. difficile to colonize the colon. Understanding which nutrients produce optimal respiratory metabolism in C. difficile will help to determine the reasoning behind whether the microbe invests its energy into various cellular processes, such as motility. Different C. difficile strains were first cultured in BHIS broth (brain-heart infusion, supplemented) and CDMM broth (C. difficile minimal media) before being used to inoculate soft agar wells. The culture growth in the wells was observed to record the motility of each strain in each condition. Initial analysis demonstrated that motility was observed to a greater extent in less viscous, minimal media. This trend pointed to the bioenergetic need of C. difficile to expend limited energy resources in exhibiting a chemotactic response towards more distant nutrient sources after metabolizing nearby nutrient stores. Additional studies were performed to elucidate the motility patterns of various mutants in both rich and minimal media in the least viscous agar condition. In this study, the motility of two wild type strains, R20291 and JIR8094, were examined along with several mutant strains that lack selenoproteins. Motility was observed in JIR8094 in defined minimal medium after several days of incubation, and this result was surprising based on the published literature. Some reduction in motility was observed in a selD mutant in both rich and defined minimal medium. These results suggest that energy derived from selenoenzymes may contribute to motility. Additional research could be conducted to test this hypothesis