As many of you know yeast and other nasty contamination are not uncommon in a C.elegans lab, and mine is recently experiencing an overwhelming one.
It seems that the entire lab is contaminated, doesn’t matter where the plates are, if in the hood or in one of the incubators, or under the microscope or on the bench. After a few days we detect fungi on the plates, always.
It is so serious that we cannot even perform a lifespan assay.
Unfortunately we don’t have access to a dedicate room for picking and we don’t have a proper biological hood with UV light to pour plates.
Does anybody has a suggestion on how to get read of these nasty contamination?
I read that for cell culture contaminations Normocin or Primocin are used. does any of you know if these compounds work also for NGM media? Or do you have eventually another compound you’d like to suggest?
Any advice will be greatly appreciated!
Thank you to you all!
this is a non-filamenous yeast? those don’t usually spread very easily from plate to plate. when we have had that type of problem in the past it was because the autoclaving was not sufficient.
if your plates have colonies inside the agar (not just on top) then this is probably the problem (or it is contamination of one of the stock solutions you add after autoclaving).
you really need to do some detective work to determine the likely source of the contamination.
The following may be helpful starting points:
What does the contamination look like? Sometimes knowing the type of contamination helps to narrow down the likely source.
Is the contamination restricted to the surface of the plate?
If you autoclave your NGM, pour some plates and then seal these plates with Parafilm, do they still end up contaminated?
Where do you pour your plates? Even without a ‘proper’ hood or UV, it should be possible to pour uncontaminated plates with care and judicious use of 70% EtOH.
Relying on anti-fungal agents is not really the answer. It’s an expensive route to take, doesn’t deal with the problem (which might get worse) and for some experiments simply not appropriate.
Thank you all for your precious suggestions. I attached a picture of the yeast contamination.
To answer Steve’s questions:
-it’s a filamentous black/green yeast
-not always, sometimes it started in the agar
-I will try n.3
-we pour the plates in a protector ventilated workstation or on a bench cleaned with 70% EtOH next to a flame
Thank you again for your help!
Aspergillus fumigatus? Difficult to be sure from the photograph and I’m no mycologist, but if it is (it’s a common mould) then it could stem from the water supply (checked by using another lab’s water to make your plates) or be in the incubator (so plates from the incubator preferentially affected) or in the lab (more difficult to pinpoint as it is carried in dust etc.).
Check your water, decontaminate your hood and workbenches. laying settling plates is probably a waste of time…but you might recognise some kind of pattern to where the contamination is more often found.
Yeah, that looks like garden variety Aspergillus. EtOH won’t kill the spores, but diluted bleach will. When we have outbreaks we go on bleaching frenzies (with gloves, coat, eyewear). If I smell plates boxes that have some mold, I give them a rinse with bleach as well. EVERY lab has this periodically. The best place to start is if you plate pourer is spraying droplets. Just a few (or even smears) on the outside of plates will fill a box with spores. And when you open plates to spot them…
“cannot even perform a lifespan assay”
You make it sound like that is the last thing to go, I’d say it should be the first!