HUGE colonies everywhere! - (Nov/10/2006 )
before i only could see them on negative plates of my E-coli. but now negative, positive everywhere! what are they yeast??? here noone ever saw then in their entire life. do I have some yeast on my skin that drops into the plates?!?!? im so confused. they are huge after just 18 hours of incubation. and after some time in the refrigirator they turn yellow. not very cute . please anyone.
umm that is bacteria.
Yeast look dry and take far longer then 18hrs to produce an appreciable colony. If the colony also looks slimy, i am willing to bet it is bacteria.
The obvious contaminant is yourself. Get your lab to coat to wash, wipe down your microbiology place with 70% EtOH, UV it if you can. The bag of plates that you have...(I am assuming your are using plates from the same bag for your work) may have all been contaminated with bacterial spores. If you want, you can leave then out on the bench and see if colonies appear. I would make new plates, if you are using plates from a stock.
Do the same clean up with your plate preparation area (if it is not the same place you do your microbiology)
im preparing new plates everytime from the powder. i dont wear labcoat....maybe that is the problem but my freinds all use same bench and they dont have such type of contamination. i mean E-coli also grow but they look tiny in comparison to those monsters they are like maybe 10 times bigger?!?!? do you have in mind what kind of bacteria that might be??? im totally lost here thank you for your help!
Forgive me if I ask the embarassing questions, but are you autoclaving the medium? Perhaps you could detail how you go about making plates. Where are the bacteria that you are trying to culture coming from? What happens if you incubate a plate with nothing streaked on it?
I also think that maybe your E. coli culture is contaminated if not your pippetes. Try phage434 suggestion.