Fluid thioglycollate media or thioglycollate broth is a multi-purpose, enriched, differentiating media used primarily to detect the level of oxygen requirement of various microorganisms. Sodium thioglycolate in the medium consumes oxygen and permits the growth of anaerobes. This, combined with the diffusion of oxygen from the top of the broth produces a range of oxygen levels in the media along its depth. The oxygen concentration at a given level can be indicated by a redox sensitive dye like resazurine that turns pink in the presence of oxygen.
This allows differentiation of facultative and obligate aerobic, anaerobic, microaerophilic organisms based upon growth at various levels in the media.As an example, anaerobic Clostridium will be seen growing only in lower portions of the media.
Thioglycollate broth is also used to recruit macrophages to the peritoneal cavity of mice when injected intraperitoneally. It recruits numerous macrophages, but does not activate them.