I work with MTB and usually make up 200ml of 1 x PBS + 0.05 % v/v Tween 80. I also use Sauton media. I was wondering if it would be ok to re-autoclave these items after using them, as I am very paranoid about introducing contamination into my experiments.
I generally make new media etc for new experiments, but sometimes I feel it is waste to through out half or more of my media that wasn't used.
Thanks
There will be a certain amount of water evaporated every time you autoclave, changing the concentration of the media. If you autoclave once and sometimes autoclave your medium twice, the change in concentration is another variable (however slight) which will be an additional factor to consider if you obtain an unexpected result. Best standardise your approach until your present study is complete.
For another unrelated study that does not require comparision to previous work (seldom occurs), then you can look at incorporating a double autoclaving approach. Maintaining the same preparation approach throughout also allows greatest confidence for comparison of minute differences in results.
If I only need to use a small amount of media such as PBS, I tend to aliquot the rest into sterile containers and store it in the reagents fridge, making sure it is sealed with Parafilm around the lid. It should last a short while, maybe a week or two.
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