Cell culture contamination.

Over the weekend my transfections were contaminated (likely bacteria) -- there was a white dusty coat/film growing above the cells.  I suspected that the OptiMEM (reagent use for transfection) is the culprit.  But then it happened again with new OptiMEM!  At the same time, Dr. Y used the same DNA preparation that I made recently for his transfection and his transfections were contaminated too.  How likely does a new preparation of midi-prep get contaminated?  Anyway, the problem was solved by filtering the DNA through a 0.2 uM filter.

After these cell culture contamination episodes, my paranoia kicked in and I began to suspect that all my cell cultures have some level of bacteria growing in them.   After careful examination the different cell lines I have been maintaining, I found these microscopic specks floating in Brownian motion around the cells.  I consulted with Dr. Y and he said that a few years back he saw the same thing so he took his contaminated cell culture samples to the pathology lab.  It turned out that they were Aspergillus!  According to Dr. Y, treatment with gentamicin will take care of this, but after reading these online blogs about Aspergillus contaminations, sounds like it is more serious than what he made out to be.  I am now geared up to do some serious decontamination of our cell culture room now.  More updates later.