Fabrication of an Auto-clavable One-Way Valve for Venting Fermentation Gases

摘要

Culturing fermentative microorgan-isms often requires that accumulating carbon dioxide be vented during growth. Preventing the release of such by-products usually causes inhibition of the organism, and this can then lead to a decreased yield of fermentation products such as organic acids and ethanol. It is common to release pressure with a needle placed through a septum covering the fermentation vessel Unfortunately, this design will only keep the system anaerobic if fermentative gases are being produced rapidly enough to result in a positive displacement of air within the fermentor Thus, the system may become aerobic as oxygen enters through the vent during the initial and late stages of the fermentation. One-way valves can be used for this purpose, but they are typically quite expensive for routine growth involving numerous culture tubes or flasks. We present a very simple and rapid method to construct an inexpensive, autoclavable one-way valve using a 1-cc syringe and a few miscellaneous items that can be found in most laboratories.