I dissolved PEG 8000 in water (670mg/ml). I need to filter it for further use in the culture, but it's kind of gelatin; seems impossible to filter. Can I autoclave it? What concentration you suggest for making a stock solution of PEG 8000?
Thank you,
Sterilize by autoclaving (120 C for 20-30 minutes should be fine). You are currently making a 67 % w/v solution. This is very concentrated.
Lower concentration stock solutions are much easier to filter. What will be the final concentration in your cultures? From there you can either decide on a 10X-100X concentrated stock solution.
Sterilize by autoclaving (120 C for 20-30 minutes should be fine). You are currently making a 67 % w/v solution. This is very concentrated.
Lower concentration stock solutions are much easier to filter. What will be the final concentration in your cultures? From there you can either decide on a 10X-100X concentrated stock solution.
Mahbobeh,
Autoclaving PEG is not recommended (See Sigma Specs), I am assuming that having your PEG at 8000mw is important for your experiment, and if you autoclave it, it will not be anymore. we routinely make up 24% PEG 8000 for virus precipitation and it filter sterilizes just fine at this concentration. As Edmund suggested above...can you lower the concentration of PEG?
good luck!
Thank you for your suggestions,
I need to apply stress in suspension culture. So, ,250mg,ml, 270mg/ml and 300mg/ml are something I assumed that work with. What stock solution could help with this concentrations you think?
Many thanks,
Hi Mahbobeh,
You haven't provided enough details for me to really know what you are doing (like what exactly it is you are trying to provide osmotic stress too...plants, bacteria?), but I suspect that you are a little bit confused, as the amount of PEG you are talking about sounds really high. I think that the numbers you have posted above may be the osmolarity measured in milliosmol/kg of H20...This does not mean that you add that amount of PEG to a solution either...this is a unit of measurement taken via a osmometer. For PEG 6000 people typically use amounts from 5 to 20% to induce osmotic stress...not sure if that would be different for PEG8000!
I don't know if this article will be helpful since I don't know what you are doing, but it might help: www.idosi.org/jhsop/2(1)10/2.pdf
Hope this helps
Ron
Dear Ron,
Thanks a lot for your helpful information. The cells are plant cell lines and drought stress is going to be applied on them at different concentrations of PEG 8000. However, I found the concentrations I referred before according to this article( http://www.fspublishers.org/published_papers/29644_..pdf), which says the selected line was obtained by subculturing, every four weeks, on fresh liquid medium supplemented with 200, 270, 295 or 310 g/L of PEG 6000 to induce water potential of -0.4, -0.6, -0.8 or -1.0 MPa, respectively (Mansour & Al-Mutawa, 2000). But, the thing is that they used it for solid culture. Perhaps that's why its concentration is so high. I see, as the reference you referred to some literatures apply PEG in different percent maybe that will work for suspension better.
Regards,
Hi Mahbobeh,
I think if the above group is doing something real similar to what you are, then you should stick with that! You will have to give up on the idea of a stock solution however. Make the media with the desired concentrations of PEG added, and filter sterilize the entire batch. You will have to get a large filter funnel for this, but it seems like the only solution. I noticed that everyone seems to be using PEG6000...are you sure you can use PEG8000? I know for our applications they are not interchangeable...not sure for these drought resistance trials though!
Good Luck
Ron
Hello Ron,
Thank you very much. Yeah it seems that PEG6000 is more desirable; there is no a special issue behind using PEG8000, because right now we just have it available, I was going to start with that one. Anyway, many thanks for sharing your useful point of view.
best,
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