I assume you don't have available an anaerobic chamber available, which of
course would solve your problem. Be careful in gassing with CO2, which
changes the pH of the medium. Perhaps nitrogen or argon would be better.
You may also need to scrub traces of O2 (which are often substantial) from
the gas.
Other reducing agents that could be used instead of or in addition to
cysteine include sodium sulfide or mercaptoethanesulfonate.
In general, I suggest that you read through a description of the Hungate
techniques. These may be more stringently anaerobic than you have a need
for, but you may get some ideas that will help. Check Methods in
Microbiology (vol. 3B).
--
David R. Boone
http://www.ese.ogi.edu/ese_docs/boone.html
Professor of Environmental Microbiology
Oregon Graduate Institute, Portland
(503) 690-1146
> Michael Casey <Michael.Casey at mbox.fam.admin.ch> wrote in article
<31D07789.6ADF at mbox.fam.admin.ch>...
> I am studying the rate of growth of Clostridium tyrobutyricum in acid
medium
> and have found them to be very sensitive to the presence of oxygen. I
follow
> the growth rate by measuring the turbidity at 650 nm. I have tried using
> different techniques to reduce the oxygen content of the medium but with
> little success.
>> Gassing with CO2 does not reduce the oxygen content sufficiently.
>> The addition of cysteine to the medium is also not sufficient but the
> presence of sodium thiogllycolate inhibits growth.
>> The addition of Oxyrase, a commercial enzyme preparation which removes
> oxygen, causes turbidity and prevents accurate measurement of growth.
>> Does anyone have an idea how I could reduce the oxygen content of
> the medium without causing turbidity?
>> Thank you.
>> --
> Michael Casey
> Swiss Federal Dairy Research Institute
> 3097 Liebefeld
> Switzerland
> Tel: (+41) 31 323 81 79
> FAX: (+41) 31 323 82 27
> email Michael.Casey at fam.admin.ch>
