I am looking for protocols to kill or rather inactivate E.coli to use it in C.elegans studies. The tertiary structure should not be destroyed, so no complete denaturation.
To control the successful inactivation, do I inoculate a small amount of LB-Medium overnight at 37°C, or will never all of the bacteria be inactivated and I will always be left with some growth? I would appreciate literature or suggestions!
There are a number of options. There are various chemicals you could use, but I think the problem might be the effect they would have on C. elegans. Heat might still be the easiest and best. I think you can effectively inactivate E. coli around 48-50C which would still leave most of the proteins and cellular structure intact, you might try 20 minutes at 50C to begin with. I would suggest just spotting a few micro-liters (at various dilutions) on an LB plate so you can determine the efficiency of inactivation. You might not need 100%, for example 99.9999% killing might suffice. But just inoculating LB broth will never give you a value, even one cell will grow out overnight in LB broth.
Thank you Michael for the answer. Have you heard of incativation by UV light? Essentially it should be the same as using it for decontamination of a cell culture bench.
Certainly, you can inactivate by UV which essentially will crosslink the DNA to the point that DNA replication fails to occur. It is important to recognize that you must be using UV-C wavelengths, that is less than 300 nm. So you need a light source that is clearly designated as germicidal.
The other problem with UV killing is one of scale, UV does not penetrate very far through a turbid liquid. So it would be reasonable to UV kill a small solution of a few milliliters, but if you want to handle volumes of say 100ml or more, then it gets more problematic unless you have appropriate flow devices.
Hi Katharina,
What kind of experiment would you like to perform with the inactivated E.coli, compound studies?
When we produced large batches of OP50 for the C.elegans community, we happen to find the solution to inactivate OP50 while keeping the structure intact. Using a freeze-drying method reduces the viability drastically but takes a long time to get the process under control. If you are interested in the freeze-dried OP50 you can always send a message to [email protected].
Good luck with your experiments!
Bas
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