The contamination battle of 2020
As the new year began, in Reproductive Sciences new projects and collaborations were on the horizon for the Endocrinology Team. We excitedly tended to our cell line in preparation for multiple experiments, but we quickly noticed something was off.
Instead of looking happy and healthy and growing well, our cells looked thin and sparse, as though they were dying. Cells in culture should have a high amount of confluency, meaning they should merge or flow into one another to nearly completely fill the bottom of the culture dish. Having small patches of open space is normal, but when cells are sparse or not merging well with one another, that is the sure sign of a problem. We could also see dark black growths within our cell culture plates, another sign that something was not right and something we weren’t intending to culture had taken up residence with our cells.
Unfortunately, this is an all-too-common issue in cell culture labs. Despite even the most rigorous cleaning schedules and seemingly impeccable use of sterile technique, contamination issues inevitably will occur in some form or another. The challenge then becomes: what do we need to fix it?
The main obstacle is there isn't one cure that will always do the trick. Contamination can come from something as simple as bacteria or fungi in the environment to as random as yeast being introduced from the skin of a lab technician who enjoys making bread at home. To be sure, these microbes are important organisms in our environment, but can wreak havoc if they make their way into unwanted spaces like our cell culture incubators.
Clean, properly working incubators are critical for cell culture. They use heat and a balance of gasses to provide the perfect environment for cells to grow and thrive. Unfortunately, this means incubators provide the optimal environment for bacteria and fungus to grow. Incubator contamination is always an annoyance, so much so it is a topic debated and discussed in depth within online scientific forums and in seminars all over the world. The difficulty in identifying the source of the contamination can be quite a frustrating and lengthy exercise in detective work.
We immediately got to work sterilizing and cleaning everything in our cell culture room. We took apart incubators, fume hoods, and refrigerators and scrubbed them top to bottom. Hydrogen peroxide, ethanol, bleach; nothing seemed to do the trick. We made fresh cell culture media and removed new, clean cell lines from the Frozen Zoo, all to no avail.
Each Friday we would go home hoping over the weekend whatever was killing our cells would have been cleaned away and we would have happy healthy cells on Monday.
We waged this war for two months. Two months of cleaning the cell culture room over and over. During our deep cleaning, we found a miniscule amount of mold hiding on the outside of one incubator which we thoroughly cleaned upon discovery. Finally, one of our team members suggested removing that incubator from the cell culture room entirely as we had begun to suspect it was the root of the contamination problem despite our careful cleaning.
In the end, removing this incubator was the key to winning the war against this unknown contaminant. This particular incubator was near the floor and was likely exposed to extra moisture from a nearby laboratory sink. Soon, our cells were back to their confluent, happy selves and the endocrinology team has been back to running our planned experiments. Along with being bigger clean freaks than ever before.