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How to Use an Inoculation Loop
to Transfer Bacteria
from Science Prof Online
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Transferring Bacteria Using an Inoculation Loop
After the inoculation wand is sterilized, the wire end with the loop is gently touched to a bacterial colony on a source plate, or dipped into a test tube of liquid inoculate, and then that sample is smeared onto a new sterile plate, typically using streak plate technique.
The freshly inoculated plate is then incubated for at least 24 hours, after which time new bacterial colonies should be visible.
Sources
- Bauman, R. (2007) Microbiology with Diseases & Taxonomy, Pearson Benjamin Cummings.
- Nester, E. et al (2001) Microbiology: A Human Perspective. McGraw Hill.
- Schauer Cynthia (2007) Lab Manual to Microbiology for the Health Sciences, Kalamazoo Valley Community College.
- Tortora, G., Funke, B., Case, C. (2010) Microbiology, an Introduction, Benjamin CuX
Article Summary: Also called an inoculation wand and microstreaker, this metal loop is a reusable tool used to transfer bacterial samples from one location to another.
How to Use an Inoculation Loop to Transfer Bacteria
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You have free access to a large collection of materials used in a college-level introductory microbiology course. The Virtual Microbiology Classroom provides a wide range of free educational resources including PowerPoint Lectures, Study Guides, Review Questions and Practice Test Questions.
Disposable swab being used to inoculate sterile TSY agar.
Microbiology is the study of microscopic organisms and infectious agents including bacteria, viruses, protozoans, fungi, algae and parasitic worms. The practice of microbiology often involves working with microbes, typically bacteria, in a laboratory setting, and transferring bacterial samples from one location to another.
Transfer of Bacterial Samples
Clinical samples (biological samples obtained from a patient) are often obtained using a sterile swab which is then streaked onto a sterile growth medium (a plate). Bacterial growth media provide nutrients, water, and a surface where the bacteria can multiply. Sometimes bacteria are transferred from one plate to another, such as when a microbiologist is trying to isolate a specific type of bacteria or when preparing multiple plates of a specific type of bacteria for microbiology students to use.
In transferring bacteria, it is important that the bacterial sample not become contaminated with bacteria from the surrounding environment. This is why media plates are sterile prior to being inoculated with a sample. The instrument used to transfer bacteria must also initially be sterile, before the bacterial sample is obtained. The entire process of trying to reduce contamination of materials used in microbiology is called practicing sterile, or aseptic technique.
Advantage of Using an Inoculation Loop
An inoculation loop is a thin metal device with a handle at one end and a looped wire at the other end. The looped end is useful for obtaining bacterial samples from colonies growing on media plates or from liquid media, as the loop can hold a drop of liquid, somewhat like a bubble wand holds liquid soap.
There are disposable devices used to transfer bacterial samples, such as sterile swabs and even sterilized toothpicks. The advantage of an inoculation loop is that it is an instrument which can be used and sterilized repeatedly, reducing the amount of contaminated lab waste generated.
There are typically two ways to sterilize an inoculation wand in a microbiology laboratory--by using an open flame, such as a Bunsen burner, or, a safer and more convenient way, to use a microincinerator.
Opening of heated microincinerator.
Page last updated: 2/4/2012
This article originally appeared on Suite101 online magazine.
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