CO2 as disinfectant,

John Hegarty goo at epix.net
Thu Mar 26 10:34:38 EST 1998


Water reaches saturation with dissolved CO2, and it will disperse
out of solution as a free gas (bubbles) and disperse with the
container's headspace (atmospheric ambient CO2 concentration is
0.03%). This rate of dispersion is affected by Henry's Law Constant
which equals the concentration CO2 in air phase divided by the
concentration in liquid phase. (At 20 degrees C Henry's Law Constant
for C02 is 1740 mg/liter-atmosphere).

An anaerobic environment (no free oxygen) could be generated by
replaced the air in a tightly sealed container with CO2, although N2
or a vacuum would be more inert. C02 would more typically be used to
create microaerophillic conditions (5-10% O2 as opposed to
atmospheric 21%).  Strict aerobes will display growth inhibition at
low O2 levels, but there is a big difference between bacteriostatic
growth inhibition and cidal disinfection.  CO2 could be used to
prevent active growth of certain microorganisms, but is unlikely to
kill them. Many persist for long periods of time in a static
condition (no-growth) until more favorable conditions present
themselves.  This is a constant concern with food products.

regards,
John Hegarty - Grad student (Helicobacter groupie)
Environmental Microbiology - Penn State
   vvvv
* HEY!  Headed to ASM-Atlanta, send me email! :) *
http://www.personal.psu.edu/jph10

________________________
>Francois wrote in message <6fbha8$41d at news1.saix.net>...
>Carbonic acid, is a weak acid, and in carbonated softdrinks  there
are still
>preservatives, so it makes sense that CO2 would not have that great
an
>effect.
>
>But what about the purging with CO2 creates so that an anaerobic
environment
>is created, which is unfavourable for aerobic microbes in water
(like
>coliforms, streptococcus etc.)




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