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Pins and Needles AND Aseptic Transfers Part 2
Submitted by Jennifer Newsted on Thu, 10/04/2012 - 9:59pm
The results are in!
After subsequent checks at 48 and 72 hours, the broth transferred to the glass bottle, two conical tubes and the cell culture petri dish are all uncontaminated! I spent approximately 30-45 seconds doing an imaginary celebratory dance in my head before I realized it is only a matter of time before I do accidentally contaminate something. As for now though, operation Aseptic Transfer on an Open Bench is a success!
Tragically, my swab of my bench area did show one colony on the plate. One. (Boo!)
Yesterday we swabbed the Biological Safety Cabinets and streaked a plate with that swab. We also did an aseptic transfer of10 mL of media from a 50 mL conical tube to two 1.5 mL tubes, and a cell culture flask. We also used some cultures of E. Coli we inoculated into broth on Wednesday to streak for isolation using thirds of the plate.
This was a new technique for me. My only other experience was in microbiology earlier this year. In fact, I even have a picture of my first streak for isolation. I'll include it below. Using the thirds of the plate was cool too, but I crossed over between the second and first third too much. It's good to see though so I can be careful not to repeat it in the future, although, it didn't inhibit me from obtaining definite isolated colonies (I estimated approximately 30). I would love to streak two plates (one with each technique) using a mixed culture to see which one is more effective for me. I doubt we will have the time for such antics because I think we're almost finished with any intentional work with bacteria.
After checking my flask from the BSC transfers today, I was unable to note any evidence of contamination even using the inverted microscope. Yay!
I did manage to locate bacteria on my swab of the BSC. I observed four colonies on my plate today. I swabbed the seams in the metal between the workbench and the back wall of the BSC. Do I know where to find bacteria or what? Hmmm. That sounded much more glamorous before I saw it in writing. This exercise is a great reminder that even though we are working in a clean environment in the BSCs, it isn't guaranteed. Utilizing our best aseptic technique in the BSCs is imperative to avoid contaminating everything.
In hindsight, I believe that being ill actually may have helped me to be exceptionally careful while doing my transfers. Now all I have to do is keep that vigilance by pretending I'm sick even when I'm not while I'm working in cell culture. I'm definitely going to put this adventure down in the W column!
Microbiology - April 2012 - First attempt at streaking for isolation.
Cell Culture - October 2012 - First attempt using this streaking method.