Durham Tubes

Durham Tubes are small, upside-down glass tubes commonly employed for the measurement and control of gas production by microbes during fermentation in microbiology labs. Historically placed in a test tube with a proper culture medium, tubes are charged with gases like hydrogen or carbon dioxide from microbial metabolism. When gas is being collected, it displaces the wetting fluid within the upside-down Durham Tube, creating a visible gas bubble that is a direct measure of fermentation activity.

These tubes are of the highest significance in enteric bacterial identification, such as Escherichia coli, in biochemical examinations such as lactose fermentation or presumptive coliform tests. Gas detection is also a very important aspect in microbial species determination and differentiation, especially in water quality analysis, food microbiology, and clinical diagnosis. For instance, the production or absence of gas in lactose broth tubes informs you regarding the metabolic activity of the organisms and thus helps in microbial differentiation.

Durham Tubes are made of superior borosilicate glass that offers thermal and chemical stability during autoclaving and sterilization procedures. Durham Tubes remain unaffected even when exposed to highly incubating temperatures or aggressive culture media, thus are most appropriate for routine laboratory use. Each tube is carefully made to offer consistent results in multiple test cycles and experimental procedures.

In practice, a Durham Tube is sterilized together with the culture medium and inoculated with the test organism. With further incubation, any microbial fermentation that leads to gas production will be contained in the inverted tube. This is a simple but highly informative optical readout with minimal requirements for sophisticated equipment in primary screening methods.

Durham Tubes have broad application in university, industrial, and government laboratories with microbial physiology, environmental microbiology, water analysis, and food protection. The fact that Durham Tubes yield instant visual proof of gas production makes them most suitable for rapid decision-making and precise microbial identifications.