[Mycology] asking for help

hardus.hatting from fabi.up.ac.za via mycology%40net.bio.net (by hardus.hatting from fabi.up.ac.za)
Tue Sep 16 08:20:33 EST 2008

Hi Paul

I am battling with Bacillus bacterial contamination in autoclaved wheat and rice at
the moment. I need to get the wheat/rice mixture 100% sterilized, but I think that this
specific strain might be heat resistant. At the moment I am autoclaving the wheat/rice
mixture at 121ºC for 30 min. I will then incubate the flasks with the autoclaved
wheat/rice mixture for 24 hours and will repeat the autoclaving again after 24 hours.
This I will repeat three times, but to my disappointment it seems that the bacteria are
not killed and after 1-2 weeks I will still loose allot of wheat/rice cultures due to
bacterial contamination.

Regarding the autoclave works 100%

1) Is the 121ºC temperature sufficient to kill the Bacillus?
2) Is the autoclaving time cycle of 30 min. sufficient?
3) How long must the autoclaving cycles be apart to make sure you kill the bacterial
4) Is there any other methods I can use to kill the bacterial spores?

I will really appreciate it if you can give me a few tips of how to get rid of this
bacterial problem.

Thanks allot

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