IUBio

any success with PdCl2 and H2 to reduce media?

gerne at my-dejanews.com gerne at my-dejanews.com
Sun Jan 3 07:20:00 EST 1999


I would expect Oxyrase to be the best reducing agent you could add directly
to the media. I haven't got the whold thread of the message, so I do not know
what the original question was, but try to have a look at the recently
devellopped SPRINT media from Oxoid if you look for anaerobe recovery.
Regards Gerhard In article <76mjd7$f0h at er7.rutgers.edu>, 
nlandau at eden.rutgers.edu (Nicholas Landau) wrote:

> Peter Stroot <p-stroot at ux1.cso.uiuc.edu> writes:
>
> >i'm looking for assistance with using PdCl2 and H2 to reduce
> >media to very low Redox levels....
> >(i want to use viologens for redox indicators...-300mV to
> >-450mV)
>
> All anaerobic chambers use the Pd catalyzed 2H2 + O2 ---> 2H2O
> reaction to scavenge O2 from the gas in the chamber.  I have not
> heard of it ever used *in* media, for the simple reason that all
> media are aqueous (or moist solids) and water drives the reaction
> in the wrong direction!
>
> Whenever this reaction is used in anaerobic chambers, dessicant is
> used alongside the palladium catalyst to insure that humidity in
> the chamber does not inhibit the reaction.  The Pd needs to be dried
> periodically in a hot oven to eliminate the accumulated H2O.
>
> I can tell you from experience that the chambers which I have used
> which employ the Pd-reaction are not reliably at -300 mV or below.
> I used to grow methanogens, using resazurin as an indicator in the
> media.  Opening a culture in the anaerobic chamber would lead to the
> slow evolution of the indicator's pink color.
>
> What is wrong with traditional Hungate technique?  Why is Pd more
> suitable for your purposes that the use of a gassing manifold and
> one of the many chemical reductants out there?  I think that you can
> use one of the sulfur II compounds (like sulfide, cysteine, or
> mercapthoethane sulfonic acid) or titanium citrate to get to the
> redox potential you need.
>
>

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