Inoculation loop

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®

References

• Black, Jacquelyn G. Microbiology: Principles and Explorations Marymount University, 1999
• Persassy
• Barbara Millicent Roberts and Mitchel
• Lloyd Alvarez