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Help Identifying Bacteria - (Apr/10/2007 )

My cell cultures seems to be contaminated by some sort of bacteria. However, the bacteria does not seem to be affecting cell growth. The cells still look healthy, are proliferating and the media is still clear. The bacteria seems to be quite slow growing. I have left the cultures in media without antibiotics for a few days but the bacteria has not overtaken the culture and the cells appears to still be viable. It appears to be a rod shaped gram negative type bacteria. I have googled slow growing bacteria but have not been able to come up with any clues as to what it might be.

I am not a microbiologist and this is probably a long shot but I am hoping someone may be able to put in some suggestions and clue me in on what steps I should take to further identify the bacteria.

Thank you in advance!!


Verbal description is very very bad way to describe a bug. At the very least you need to do a biochemical assay to have some idea of what it its. what can it metabolise sugar types, lipids, types of amina acids, interesting by products, aerobic, anaerobic, etc

Rod shape, gram negative, really doesn't mean much. eg Animal has eyes and legs...what could it be?

So my best guess would be to grow these bugs as a pure culture. Once you got that, you could do some sequencing on ribosome DNA. The sequence data should allow you to at least place the bug on the right branch.

But do you really need to know what this contaminant is?


Thanks for your reply. I should have worded my question a little better. I have a hundred thoughts on my mind but I cannot seem to piece everything together to form a coherant question.

I do not need to know what exactly the contaminant is ie the specific type of bacteria. No one here is a microbiologist and from what little we know of microbes, we are assuming their reproductive/growth cycle is very fast. If that is the case, the cultures should have been overtaken by bacteria especially without the presense of antibiotics in the media. However, I am not seeing it with this particular strain and I can't find any literature on it. I am wondering if such a bacteria type strain does exsist?


what makes you think it's a bacterium? why not a yeast, or other small fungi?

posting a pic would be a very good idea smile.gif

have you actually done a gram stain?

also, why does it matter what it is? if it's contaminating your cultures, then you can't trust your cells to act the way they are supposed to in experiments. my best advice is to throw them out and start over. any sort of organism coexisting in your cultures will result in altered signalling, expression patterns, etc...all sorts of things that could give you strange results if you try to do experiments on these cells