Inoculation loop

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An inoculation loop.

An inoculation loop, also called a smear loop, inoculation wand or microstreaker, is a simple tool used mainly by microbiologists to retrieve an inoculum from a culture of microorganisms. The loop is used in the cultivation of microbes on plates by transferring inoculum for streaking. Also it can be used to transfer microscopic organisms. Touching a broth or a culture plate will gather enough microbes for inoculation.

The wire forms a small loop with a diameter of about 5 mm. The loop of wire at the tip may be made of platinum, tungsten or nichrome, the latter being inferior but less expensive. This loop removes a consistent amount of the liquid suspended inoculum by using the phenomenon of surface tension.

The inoculation loop is sterilized in a fire, often using a device called the Bacti-Cinerator®, until it becomes hot before and after each use. Heating for 5-7 seconds is enough to render the inoculation loop free from all forms of life. By doing this, the same tool can be reused in different experiments without fear of cross-contamination. After flame sterilization, the loop must be cooled so that the next cells the loop touches are not killed by the hot metal.

The device known as Bacti-Cinerator®


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