Black bits in DMEM... help! - (Aug/14/2007 )
Does any one else notice bits (some black, some not) in DMEM (both in 10% FCS and others). They are mostly often long and stringy. I checked other ppl's media in the lab and they have it too... is this contamination or?
We have not observed any bits on DMEMeven when kept at 4C for a long time. It could be some contamination.
I have noticed, small bits, white in color, in FCS if kept at 4C for a long time.
you may incubate your serum dmem in 37 degree for 2-3days, and stain it with mtt.
if it could be stained by mtt, i should say you are shooted... ...contaminated!
dispose your medium...
may be fungus, Aspergillus spec???
black stuff in anorganic chemistry are f.i. some salts of ferrum or sulfides but should not be in such high conc that it would precipitate...
Firstly , In DMEM alone there should be NO debris visible under the microscope.
Secondly, if you have added FBS/FCS to your DMEM, then it is perfectly normal to see " long, stringy" bits of debris. These are normally precipitated proteins inherent within the FCS/FBS. As your serum ages then the debris increases. This is of course assuming your serum is from a quality company like Sigma, Invitrogen, PAA, Biosera, Autogenbioclear, Moregate TCS, Biowhittaker etc.
Contamination will increase dramatically over just a few days. Take a sample and leave it in the incubator. An experienced eye will be able to tell one from the other.
In my Institute I teach cell/tissue culture. Spotting potential contamination from normal debris is the most difficult thing to teach i.e. yeast, bacteria and fungal contaminants.