Aseptic Transfer Technique

An Overview of the Importance of Aseptic Transfer Techniques in Microbiology Labs

• The Aseptic Transfer Technique is an essential method aimed at preventing contamination of cultures.
• Microorganisms are omnipresent in our surroundings - from the air we breathe to the surfaces we touch. Understanding their heavy presence underscores the necessity of Aseptic Transfer Techniques in microbiology labs to mitigate the dangers of contamination.
• It is particularly challenging in a microbiology lab as we aim to work with pure cultures, ensuring our experiments involve a single species of microorganism for precise research and accurate results.
• While culturing microbes, it is crucial to operate under the assumption that everything, minus the sterile culture media, is potential capital for contamination.
• When the agenda involves transferring cells to new cultures, it is essential to sterilize anything and everything that harbors the potential to pollute these cultures.

An Overview of the Importance of Aseptic Transfer Techniques in Microbiology Labs

In the mid-1800s, Louis Pasteur developed the techniques of aseptic transfer to minimize the risk of culture contamination (and the risk of making oneself sick). In today’s lab we will learn the steps in aseptic transfer.

Key Considerations for Practicing Aseptic Handling

• For effective aseptic handling, maintaining a clean, dust-free lab environment is imperative. In such an environment, one must refrain from actions such as coughing, sneezing, and talking while working.
• Ensuring the stoppers and plugs of culture containers are tightly secured is crucial. These containers, once secured, should only be opened for a minimal amount of time.
• The plugs should not be placed on the working tables.
• When using pipettes in the aseptic procedure, they should only be unwrapped right before use to maintain sterilization, especially when in the aseptic zone.
• If wire loop is to be used, it should be sterilized by directly heating until it becomes red hot.
• It should be allowed to cool sufficiently before using it for any aseptic work.
• If sterile liquid is to be poured from one sterile container to other the mouth of both the containers should be flamed.

Materials Used

1. A bacterial culture suspension
2. Wire-loop
3. Nutrient medium containing tube or Petri plate

Method of Aseptic Transfer Technique

1. Loosen, but don’t remove the cotton plug on the tube. Hold the inoculating loop at the end of the rubber/plastic portion of the handle.
2. Stick the loop into the flame until it becomes RED HOT. Flame the entire wire loop and about half of the metal portion of the handle (because part of the metal portion will extend into the test tubes).
3. Remove the caps and hold them in the same hand as the loop.

Where could aseptic technique used for?

In operation theater we should be very clean and starile. We should use aseptic transfer technique during such a sensitive phase.

1. Handling surgery equipment in operation theater.
2. Helping with a baby’s birth by vaginal during birth delivery.
3. Handling dialysis catheters.
4. Performing dialysis.
5. Inserting a chest tube.
6. Inserting a urinary catheter.
7. Inserting central intravenous (IV) or arterial lines.
8. Inserting other draining devices.

Precaution during Aseptic Transfer Technique

• To avoid contamination of the cotton plugs: don’t set them down on the bench top; don’t touch the cotton plug at the bottom (that enters the tube)
• Flame the mouths of the test tubes. The mouths may be contaminated. We don’t want to drag the loop across the mouth of a tube and contaminate our culture.
• Cool the loop by tapping it on the sterile agar or in the sterile broth.
• Insert the loop into the stock culture to obtain [a small amount of] cells. You don’t need to see cells on the loop to have enough.
• Take out the wire loop and reset the cotton plug in the tube.
• Re-flame the mouths of the tube. Then put the caps back on. Keep tube in test tube holder.
• Take the medium containing tube to which the culture has to be transferred.
• Immediately transfer cells to the sterile medium.

This should be very quick

• Remove the cotton plug and flame the mouths of the test tubes.
• Insert the loop into the medium and mix the culture in it.
• Take out the wire loop; re-flame it and reset the cotton plug in the tube.
• Incubate the tube under appropriate conditions and record the results.

References

• https://vlab.amrita.edu/?sub=3&brch=73&sim=212&cnt=1
• https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_Labs_II/Lab_02%3A_Aseptic_Technique_and_Transfer_of_Microorganisms
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941987/
• https://microbenotes.com/general-aseptic-techniques-in-microbiology-laboratory/
• https://openwetware.org/wiki/BISC209:_Aseptic_Transfer
• https://www.medicalnewstoday.com/articles/323615
• https://biocyclopedia.com/index/biotechnology_methods/microbiology/aseptic_technique_and_transfer_of_microorganisms.php

Further Readings

1. McFarland Standards
2. Bacterial Flagella, Fimbriae and Pili
3. Fimbriae vs Pili
4. Fimbriae vs Flagella
5. Growth Curve of Bacteria
6. Spread Plate Technique
7. MacConkey agar
8. Bacterial Growth and Nutrition
9. Serial Dilution in Microbiology
10. Streak Plate Technique
11. Extremophiles
12. Monochrome Staining
13. Acid fast staining of bacteria
14. Negative Staining
15. Instruments used in Microbiology Laboratory
16. Algae

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