Search terms

Sometimes, a search engine term shows up in my stats that I feel I should address.  Today, it’s this:

ypd media does it ever go bad

No.  Well, it does get contaminated (if it’s cloudy, it looks contaminated).  Then, you need to get rid of it.  But, in general, I have used media that is a few years old and the cells grew fine (I was desperate and I found some that belonged to some former student).  Beyond that, I suppose I couldn’t say, but usually people use their media within a year or so of making it.  If you don’t, then you are likely making too much at once which I wouldn’t recommend because of the risk of it becoming contaminated before you get around to using it.

At least, that’s what I assume you mean when you ask if it goes bad.  If you are talking about how it gets darker after autoclaving, then I would say that is normal–it’s just the sugar carmelizing.  If you leave it in the autoclave longer than a typical 20 minute cycle, it can get quite dark–almost black.  It’s still okay to use, though.

There, that’s my public service for today.

2 thoughts on “Search terms

  1. I just though I’d add that while old YPD is probably fine for most purposes, there are some amino acids (I’m looking at you Tryptophan) that get degraded over time by exposure to light, so if that old YPD has been sitting around in a lighted room then your trp1-1 cells might grow less well than in new YPD.

  2. Hi,Im a post-grad student in of a local uni in Asia and now working on pichia pastoris.I have no experience working with pichia.I prepared a bottle of YPD and left it in room temp and the next day it has gone a bit cloudy.does this mean it has been contaminated?if so do i have to discard it?Thank you very much…

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