I used these lots all the time in the past and I always had this
clotting. STrangely the amount varied with the bottle, some didn't show
any clotting, some had a real thick waxy bottom. It seems to be
time-dependent and it occured in a much "heavier" way after I kept it in
the fridge for some days.
I talked to someone in the lab and she knew about this problem and
therefore always used absolutely fresh media (that wasn't stored at
4°C). Anyway, I don't think this should be normal! I still had these
huge flakes in my culture after incubating over night. I'm not sure if
it affected growth, but it could possibly interfere with my downstream
processing, could it?
Marion
albican at my-deja.com wrote:
> In article <3805A220.E1FB186 at mpiib-berlin.mpg.de>,
> Marion Elflein <elflein at mpiib-berlin.mpg.de> wrote:
> > here's the recipe:
> >
> > per 1 l:
> >
> > 15 g Proteose Peptone (Difco)
> > 5 g NaCl
> > 1 g Starch (soluble)
> > 1g KH2PO4
> > 4g K2 HPO4
> >
> > ad H20 to 1 l, pH 7,5
> >
> > autoclave
> >
> > before incubation, add
> >
> > 10 ml Vitaminmix
> > 5 ml NaHCO3 (8,4%)
>> Is this the first time you used all of these exact ingredients (lot
> numbers) together? I would take a hard look at the starch. It is
> possible that these lots won't work together, but the next one will.
> The chemicals do not change, but the peptone and the starch do vary
> from lot to lot.
>> --
> Albican
> Biologist masquerading as a Microbiologist
>> Sent via Deja.com http://www.deja.com/> Before you buy.
albican at my-deja.com wrote:
> > I've got a problem with my medium for Neisseria gonorrhoeae, Proteose
> > Peptone. After autoclaving, there's some (a lot!) precipitation. The
> > clots have a rather waxy appearance, and do hardly dissolve even after
> > heating in the microwave.
> >
> > Did anybody else ever encounter this problem? Could it be the starch?
> >
> > I felt a bit unhappy "feeding" this to the bacteria...
> >
> > Thanks a lot,
> >
> > Marion
>> Sounds odd. I have never seen P.P. form precipitate, unless it is
> highly concentrated (or QC reject). It sounds like you have "flock" (a
> flocking flask). Is this the first time you used this lot? How does
> the powder look? Is it very "powdery", or has moisture gotten to it?
> You might concider throwing it away and getting some new stuff.
> Difco/BBL peptones seem to always perform well.
>> --
> Albican
> Biologist masquerading as a Microbiologist
>> Sent via Deja.com http://www.deja.com/> Before you buy.
--
Marion Elflein
MPI für Infektionsbiologie
Monbijoustr. 2
10117 Berlin
030 / 28 460 440
elflein at mpiib-berlin.mpg.de
