An anaerobic chemostat that permits the collection and measurement of fermentation gases.

A chemostat was designed to allow anaerobic growth in the culture vessel in the absence of a continuous stream of O(2)-free gas. Produced gases were collected within the culture and collection vessels, and pressure build-up was prevented by allowing gases to expand into a collapsed football bladder. The culture overflow was collected in a flask, held at 0 C, that was emptied by applying a positive CO(2) pressure to the system. Ruminococcus albus, a H(2) and CO(2)-producing anaerobe, was used to test the operation of the apparatus. H(2) production was measured by sampling the various gas spaces of known volume and measuring H(2) concentration by gas chromatography. Measurement of accumulated fermentation gases and the effects of the accumulation on fermentations can be studied with the apparatus.