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G. rubri no longer turning pink in liquid or plates

| posted 17 Sep, 2018 15:32
This year we've switched to Gordonia rubripertincta. Initial streak plates from the stock Debbie sent to us grew pink as expected, as did the subsequent P1FF and P2FF cultures. Plaque assay plates from direct isolation experiments also turned pink. This past week, however, they have failed to turn pink, and a new P1FF culture taken from the same pink P0FF streak plate as earlier grew as a tan/yellow solution after two days of growth in a shaker incubator. Incubations (including shaking) is always at 30C.

I know the pink color accumulates over time, but I am trying to figure out why they are not turning pink now, when they did before. Aside from the usual things like testing new PYCa media, etc, I was wondering if anyone else has encountered a similar problem and can tell me a) should I be concerned, and b) ideas for what the problem might be, if any.
| posted 17 Sep, 2018 15:55
The simplest explanation is one of the following:
a. you have a non-pigmented mutant
b. it is a contaminant (and no longer G. rubi)
I would recommend going back to the frozen stock.
Edited 17 Sep, 2018 16:10
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