Monday, November 29, 2010

Re: astrobiology sterility vs disinfections

Hi Mel,
H2O2 is stable if stored correctly - it's been used as a storable rocket fuel oxidiser for instance. However, it can be broken down by an inorganic catalyst.... Perhaps we could inject, say, a palladium slurry instead of catalase?
But it's all just more and more plumbing!
Catalase is a much more efficient catalyst for breaking down H2O2 (hence it's name) so it would be fun to see how Catalase, Bugbuster and TwistDX co-exist! Or Palladium, come to that.

Hey Ol
does hydrogen peroxide have a relatively short hald life? could we take advantage of that? or will the cold prevent in breaking down by itself?

astrobiology sterility vs disinfections

Hi Mel,
If I can tear you away from Fluxx for a moment, what do you think of the below?:
Basically H2O2 is the gold-standard for astrobiological decontamination, but can we do this in flight?
Are we getting closer and closer to the minirobot idea?
(I.e lots of things to pipet so a pipetting robot not valves?)




Many thanks, Lynn - if we tried to disinfect a system in the field or during flight (my long-term ideal) we would need to flush out or neutralise the H2O2 before adding reagents (eg TwistDX etc). The question then is whether the reagents can tolerate the presence of Catalase etc. Unless we need to flush out the Catalase etc too...

For trying to sample at altitude, something like Catalase might be problematic since the relatively high torr O2 released might nuke anything in the sample (since it would have evolved in a far less O2 -rich environment)

Perhaps this protocol is best used for in-the-lab sterilisation? I have often thought that actually we have access to a lot of plasticware that has been gamma-irradiated (the gold standard for being sterile AND is DNA-free, which is a separate criterion) and we could then try to sterilise plumbing etc (eg Tygon) with H2O2?

This is somewhat what I had in mind for this summer's HAB device but in practice the syringes etc needed too much fiddling to mount them sterile. I tried a ethanol flush during the rocket launch preps but that's a moot point now :-O ;)


Fw from Lynn


I did conduct a literature search on Hydrogen Peroxide for spacecraft cleaning.

As noted for astrobiology/planetary protection for the mars missions of the 70s Solutions of 3, 10, and 15% hydrogen peroxide were found to have pronounced bactericidal effects, as a function of time of exposure, on sporeformers and nonsporeformers isolated from spacecraft. Find the attachment, applmicro00028-0236

It appears the UMS should be cleaned with the least toxic concentration 3% as exposure time can be long 4 hours.

The disinfection Nov 2008 guide has a selection of agents for disinfection listed if H2O2 cannot be used.

I hope all is well