Aseptic Technique

Aseptic Technique

Introduction

Aseptic technique is used for several procedures by microbiologists. These procedures include transferring cultures, inoculating media, isolation of pure cultures, and for performing microbiological tests. Thus, this experiment is a very important one which serves as basics for other microbiology procedures. Aseptic techniques involves using procedures to prevent contamination from pathogens.

During aseptic technic,

  • Disinfect the tables with antibacterial cleaner.
  • Wear gloves and lab aprons.
  • When labelling Petri plates, always write on the bottom of the plate.
  • When using incinerators, give them ample time to warm up before sterilizing loops or needles. DO NOT leave loops or needles unattended in the incinerators. They will melt!
  • When inoculating cultures, always sterilize your loop or needle before going into a culture and after transferring it. Sterilize the loop even if you are going back into the same culture again.
  • Make sure you let your loop cool first – you don’t want to kill the bacteria.
  • After removing the lid of a test tube, briefly flame the mouth of the tube before inserting your inoculating loop, and flame again before replacing the cap.
  • Don’t put anything down on the table – loops, needles, pipettes, test tube lids, etc. Once they touch the table they are no longer sterile.
  • Loops/needles can be placed temporarily in slots on the sides of incinerators.
  • Test tube lids can be held with pinky finger.
  • Pipettes should remain in canister until just before use.
  • Do NOT leave media open to the air – bacteria and fungi in the air can contaminate the media.
  • Don’t over-inoculate! It doesn’t take much inoculum to start a culture. Simply touch the loop or needle to the bacterial growth and obtain a small amount on the loop. Don’t “scrape” the culture, and don’t dig into the agar.
  • When streaking onto an agar plate or slant, make sure the loop doesn’t break the surface of the agar. A gentle gliding motion is all that is necessary to distribute the bacteria on the plate.
  • When finished, disinfect the tables again with antibacterial cleaner. Dispose of gloves in the biohazard trash, and place aprons back in your designated drawers. Wash your hands!

References

  1. Keiser, G.E. ‘Laboratory manual’
  2. Cain, D., Hanks, H., Weis, M., Bottoms, C., and Lawson J. ‘Microbiology Laboratory Manual Biol 2421L Revised Spring Edition’

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