Working with C. difficile in a Hypoxic Chamber.

Clostridioides difficile is an enteropathogen responsible for diarrhea under conditions leading to a dysbiosis of the gut microbiota, in particular after an antibiotic treatment. It is a spore-forming obligate anaerobe, which is, as such, usually cultivated in anaerobiosis in laboratories. Yet the gastrointestinal tract (GIT), its natural niche, is not completely deprived of oxygen (O2) and the O2 tension in the gut even rises under conditions of dysbiosis. C. difficile is able to tolerate the low O2 tensions it encounters in the GIT. C. difficile spores germinate in the small intestine at 4% O2 and the bacteria are found close to epithelial cells where the O2 tension is between 1% and 2% O2. To understand how this anaerobe deals with the oxidative stress found in its environment and to investigate its physiology in atmospheric conditions closer to the O2 exposure encountered in the GIT, experiments can now be performed in hypoxia chambers in which the O2 tensions can be modulated. This chapter details how to investigate C. difficile biology in hypoxia.