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How to Use a Microincinerator in a Microbiology Laboratory
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This sterilization instrument consists of a ceramic tube surrounded with metal and with a hollow portion at the center. When plugged in and turned on, the microincinerator can reach temperatures of 800 degrees centigrade, more than sufficient to incinerate any organic material on an inoculation loop.
Why Is a Microincinerator Necessary?
In a microbiology laboratory contamination of sterile materials must be avoided, and this can be difficult since bacteria and fungal spores are present throughout the surrounding environment. Avoiding contamination requires use of aseptic technique as well as being constantly mindful of each action performed in the microbiology laboratory.
Sometimes bacteria that are purposely grown in a laboratory environment must be transferred from one location to another, such as when a microbiologist is trying to isolate a specific type of bacteria from a clinical sample or when multiple Petri plates of a specific type of bacteria need to be created for a classroom of microbiology students.
Bacteria are often transferred using an inoculation loop (a.k.a. inoculation wand). This instrument is essentially a wire with a small loop at one end and a handle at the other. Since it is made of metal, it can be repeatedly used and then resterilized in a flame or microincinerator. Open flame, however, is potentially dangerous, whereas sterilization by microincinerator is relatively safe.
Article Summary: A microincinerator, also known as a bactoincinerator, is a device used in microbiology laboratories to sterilize instruments.
Use of a Microincinerator in Microbiology Laboratory
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Microincinerator with slide tray for heat fixing bacterial smears.
Sterilizing an Inoculation Wand: To sterilize a loop, place it in the hub (opening) of the microincinerator for just a few seconds, until the portion of the inoculation wand that is being sterilized glows red. Once the loop is removed from the incinerator, it almost instantly stops glowing, and within 20 seconds or so, will be cool enough to use.
Heat Fixing Bacterial Smears: A bacterial specimen on a microscope slide is called a smear. It is prepared using a bacterial sample obtained with an inoculation loop that is then mixed with water or physiological saline in the surface of a microscope slide. Bacteria are very small and essentially colorless, so the bacterial smear must eventually be stained in order to be visible when viewed through a microscope.
So that the smear doesn’t wash away during staining, it is heat-fixed, using either the open flame of a Bunsen burner or, preferably, a slide platform affixed to the top of a microincinerator (see photo below). By placing the bacterial smear slide on the hot slide platform for several minutes, the bacteria are killed and the smear is affixed to the slide so that it will not wash off during staining.
Sources
- Schauer Cynthia (2007) Lab Manual to Microbiology for the Health Sciences, Kalamazoo Valley Community College.
- Bauman, R. (2005) Microbiology. Pearson Benjamin Cummings.
How Is a Microincinerator Used?
There are two main purposes for which a bacto-incinerator is used in a college microbiology laboratory:
- sterilizing an inoculation loop
- heat fixing bacterial smears onto microscope slides
Inoculation loop shown with plate of sterile TSY agar
Page last updated: 2/4/2012
This article originally appeared on Suite101 online magazine.
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