Which item is used to retrieve an inoculum from a culture of microorganisms?

• A. Pipette-Aids
• B. Microcentrifuge Tubes
• C. Petri Dish
• D. Inoculating Loop

Answer: (D)

The main idea is picking up a small amount of microorganisms from a culture to start a new one. An inoculating loop is specifically designed for this. It’s a thin, sterilizable wire with a loop at the tip that can touch the surface of a solid culture or reach into a liquid to collect a tiny amount of cells. Before use, the loop is sterilized by flaming and then cooled to avoid killing the organisms or causing contamination. Once cooled, you touch the loop to the culture to obtain the inoculum and then transfer it to the new medium, such as by streaking on an agar plate or into broth. The other items have different roles—picking up liquids with a pipette, storing samples in tubes, or simply providing a growth surface—so they aren’t the best tool for retrieving an inoculum.