[DIYbio] Re: Contamination. Help needed!

Hi,

No idea what this is, but I can tell you what its not, maybe that helps:

- It's definitely not yeast, that looks very different. Yeast would consist of small groups (4-10) of oval particles, smaller than a mammalian cell, with a well defined, smooth outline. They would also outgrow your cells and kill the culture in a matter of days. This is not like that.

- It's not mycoplasma or a virus as both are too small to resolve in a light microscope. They would simply not be visible even in a rampant infection.

- It is not usual cell debris as it is moving.

My best bet is that it is some form of bacteria. Were you using penicillin-streptomycin in your medium? If not, try adding that. You can also add some Fungizone too if you are desperate, as it might be some fungus.

However, such "resurrected" cultures are never really perfect as the cells were put under stress and they might be permanently altered, even if appearing completely cleaned at some point. I would just discard the whole culture along with any media and buffers that are in use, autoclave any equipment that came into contact with it and thoroughly wash incubators and culture hoods with Virkon, or your disinfectant of choice.

If this is showing up in multiple cultures, then the source of contamination is not within the culture itself.

Maybe this helps.

Mate



On Wednesday, 29 July 2015 14:21:08 UTC+1, Cindy GRANDJENETTE wrote:

Dear all, 

We have problems of contamination in several of our cell lines. Cell viability is pretty good, however, cell morphology is affected whatever the cell line. In addition and importantly, we observe a lot of small particles in the medium. Their number increase over time.

Mycoplasma tests were negative. We also sent our samples to 2 microbiological labs. Nevertheless, they were not able to identify the source of our contamination. We are wondering whether these contaminations are due to (myco)bacteria, viruses, or even yeast.

You may find attached movies showing how these particles "appear". The morphology of this cell line is normally homogeneous with round cells.

https://www.dropbox.com/s/n1p711dwfxnzxgy/150724%20tf1%202h30%20mes%205%20min%202%28converti%29.mov?dl=0

https://www.dropbox.com/s/ggbt1u8i3piau0q/150724%20tf1%202h30%20mes%205%20min.avi?dl=0

https://www.dropbox.com/s/sp2ncal7szl2kkr/150726%20tf1%202%20min%20mes%20100ms.mov?dl=0

https://www.dropbox.com/s/c0okt4k3twgzg4z/150726%20tf1%204h%205%20min.avi?dl=0

https://www.dropbox.com/s/6ngjhzcy9fejzjn/TF-1%20big%20cell.avi?dl=0

Does somebody have an idea concerning this contamination ? 

Thanks for your help,

Cindy