What is a glycerol stock used for in microbiology?

A glycerol stock is a method used in microbiology to preserve bacterial cultures for long-term storage. By mixing bacterial cells with glycerol and freezing the solution, researchers can protect the cells from damage caused by ice crystal formation during the freezing process. Glycerol acts as a cryoprotectant, allowing the cells to survive the freeze-thaw cycles and maintain their viability over extended periods, often years.

Choosing the option that states glycerol is mixed with liquid cultures for long-term storage accurately describes the primary purpose of glycerol stocks. This method ensures that researchers can easily revive and use the cultures in future experiments without having to repeatedly grow new cultures from the original source, thus saving time and resources while maintaining strain integrity.

The other choices focus on different aspects of microbiological practices—creating living cultures, measuring bacterial concentrations, and performing inoculations—none of which specifically highlight the preservation function offered by glycerol stocks.