Hi All,
Recently I moved from a C. elegans lab to a lab that does a little C.
elegans (two of us). Since the move, my plates look strange with the
OP50 appearing brittle. That is, when you touch the surface with a
pick, it tends to crack instead of being the normal soft and sort of
creamy consistency I'm used to. I don't think this is a
contaminating strain of bacteria for the following reasons: 1. It
looks and smells normal; and 2. I've tried streaking out fresh OP50
from four different worm labs here and from a CGC plate I was sent
harboring a worm strain and get the same problem. Plus, it's slow
growing; doesn't take over the plate like most contaminating bacteria.
What is the problem here? The worms are happy (phenotypes are
consistent, crosses work), but it's driving me nuts.
I assume the problem may be with my plates, so here is how I make them, FYI.
For 1 liter of NGM:
3 g NaCl
17 g Bacto-Agar (Becton, Dickinson)
2.5 g Bacto-Peptone (Difco)
Add 975 ml ddH20, autoclave
Add 1 ml 1M CaCl2; 1 ml 1M MgSO4; 12.5 ml 1M KPO4 buffer (made w/
monobasic and dibasic, pH 6.0)
(Sometimes I add 1 mg/ml uracil as per some recipes, but this doesn't
corrolate with the OP50 problem.)
Add 1 ml 5 mg/ml cholesterol in EtOH.
That's it. Thanks for any ideas.
Andy
Andrew G. Spencer, Ph.D.
Department of Biochemistry
University of Wisconsin-Madison
ph: 608-262-0005 x3428
em: aspencer at biochem.wisc.edu
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