Fermentation tubes, also known as fermentation flasks or fermentation vessels, are laboratory glassware used in microbiology and biotechnology for various fermentation processes. Here’s an overview of their features and uses:

1. Material: Fermentation tubes are typically made of borosilicate glass, which is resistant to thermal shock and chemical corrosion. This glass type ensures the integrity of the vessel during fermentation processes involving heat and acidic or basic solutions.
2. Design: These tubes often have a cylindrical or conical shape with a narrow neck and a wider base. The narrow neck allows for easy attachment of rubber stoppers or airlocks to create a sealed environment for fermentation, while the wider base provides stability.
3. Graduations: Many fermentation tubes feature graduated markings along the side, allowing for precise measurement of liquid volume during the fermentation process. These markings are particularly useful for monitoring the progress of fermentation reactions and determining the rate of gas production.
4. Airlock Compatibility: Fermentation tubes can be equipped with airlocks, which are devices that allow gas to escape from the vessel while preventing air and contaminants from entering. Airlocks help maintain anaerobic conditions within the fermentation tube, which is essential for certain types of fermentations.
5. Capacity: Fermentation tubes come in various sizes to accommodate different batch sizes and volumes of fermentation media. Common capacities range from a few milliliters to several liters, depending on the specific application.
6. Applications: Fermentation tubes are used in a wide range of fermentation processes, including the production of alcoholic beverages (such as beer, wine, and spirits), fermentation of dairy products (such as yogurt and cheese), microbial biomass production, and pharmaceutical fermentation for the production of antibiotics, enzymes, and other bioactive compounds.
7. Sterilization: Prior to use, fermentation tubes must be sterilized to eliminate any microorganisms that could contaminate the fermentation process. This can be achieved through autoclaving, dry heat sterilization, or chemical disinfection methods.
8. Sampling Ports: Some fermentation tubes may feature sampling ports or septum caps, which allow for aseptic sampling of the fermentation broth without compromising the integrity of the vessel. This is particularly useful for monitoring cell growth, metabolite production, and other fermentation parameters.

Overall, fermentation tubes are essential tools in microbiology and biotechnology laboratories for conducting fermentation experiments and producing a wide range of fermented products. Their durable construction, precise measurement capabilities, and compatibility with airlocks make them indispensable for researchers and fermentation enthusiasts alike.