Hi, I'm Meghan, a scientist at Addgene
Aseptic technique is a critical skill for success in numerous fields such as microbiology,
molecular biology or cell biology.
In this instructional video we will provide an overview of some of the key strategies
of aseptic technique, including personal protective equipment, setting up a clean workspace and
maintaining sterility while working.
Before beginning any experiment make sure that you are wearing the appropriate personal
protective equipment, including a lab coat, gloves and, if necessary, safety glasses.
As we mentioned during our protocol on “Getting Started With Tissue Culture”, body flora
can be a common cause of contamination in reagents.
To reduce the risk of contaminating your samples with body flora, ensure that your arms and
wrists are covered by a cuffed lab coat or disposable arm cuffs.
While gloves are meant to protect users from the material they are working with, they also
protect the material from user contamination.
To keep your gloves clean, avoid touching your skin and hair, as well as your cell phone,
writing utensils, or other unsterilized objects.
Always change your gloves if you touch something unsterile or are starting a new task.
Before beginning any task, clear the workspace of unnecessary materials.
Set up all materials so that they are in arm’s reach with clean and dirty items clearly separated.
We recommend working from left to right with all clean items stored on the left and waste
bins to the right.
If you are going to be using a bunsen burner or candle jar, make sure that the space around
the burners are free of loose papers or laboratory wipes.
Finally, wipe down the workspace and pipettes with 70% alcohol and allow it to evaporate.
Before beginning a task, examine all of your materials for signs of contamination or signs
that the sterility may have been compromised.
Check all autoclaved items to ensure that the indicator tape has changed colors.
For items that are covered with foil check for tears or holes for capped items, ensure
that the cap has been tightly sealed.
When working with agar dishes, examine the dishes for signs of microbial growth.
Foil is often used as a cover for bottles and beakers.
Before beginning your work, gently loosen the edges of the foil, so it is easier to
remove.
When ready, gently lift the foil with one hand and keep it upright, to prevent contamination
of the sterile side.
While working, keep the foil in your hand rather than putting it down on the lab bench.
Work quickly so that the beaker does not sit uncovered for an extended period of time.
When working in the lab with sterile liquids in glass bottles, gently loosen the cap before
starting.
Using one hand, remove the cap from the bottle.
To prevent the sterile side of the cap from becoming contaminated, do not put the cap
on the lab bench.
Instead hold it in your hand upright as you work.
While holding the bottle at an angle, gently pass the neck of the bottle through the flame.
Before recapping, pass the neck of the bottle through the flame a second time.
If you are going to use the bottle again, you can leave the cap loosely sitting on the
top of the bottle.
Once you are finished, however, be sure to cap the bottle tightly.
Metal objects such as forceps and spreaders are used and reused frequently in the lab.
While these items can be sterilized in an autoclave, it is often more convenient to
disinfect with alcohol and a burner.
To sterilize, dip the portion of the instrument that will be used for the procedure in 70%
alcohol.
Pass the alcohol-dipped portion of the instrument through the flame of the burner to ignite
and then allow the alcohol to burn off.
If you are going to use the instrument on a live culture, such as bacteria, touch the hot tip to the inside
of a sterile tube or the surface of an uninoculated culture to cool before contacting the specimen.
Agar dishes are used in the lab to culture bacteria such as E. coli.
To reduce the risk of body flora contamination when working with agar plates, do not fully
remove the lid of the agar dish.
Instead, hold the lid at 75-90 degree angle toward you and inoculate from behind.
The lid will form an additional barrier against unwanted contamination.
Thank you for watching this aseptic technique video.
For more useful videos, protocols or blog posts please visit Addgene’s website.
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