Bis-tris propane

thank you!

Thank you for an answer!

I will learn with buffers you mentioned. And as for carbon source.... S.alkalinus can grow on starch medium but develop abundant fruitification as many other fungI. And this is a problem as now we interested in mycelium and conidia for which mono- or oligosaccharides are preferred....

Yes..I agree with Tobias Goris with valuable information. Sigma Aldrich website have Buffer Reference Center which provides valuable information ...... 

Thank you!

I now study this to make a choice.

I fully endorse the answer of Dr.Tobias Goris.

Thank you for your opinion.  One problen is that as I found,  referred buffers provide only extremely alkaline pH. Though I  need  to reach  pH at about 7-8 as well as pH above 9 (ideally 10) using similar compounds. And a very important addition: Na+ ions must be completely excluded in my media...

The usual is carbonate buffer for high pH culturing.

Tris-HEPES is probably not a good choice as they have very similar pKa. You can try phosphate/borate from KH2PO4 and boric acid and adjusting with KOH if needed so you can avoid the Na... in any case you'll have some Na from the glass specially at high pH

Thank you for suggestion. I agree with you about TRIS-HEPES and that's the reason I'm searching for alternative.

We use plastic dish in such cases

Sorry, I just realised you asked for organic buffers and my suggestion was inorganic.

Then, based on pKa values a potential combination could be Tris-HCl (tricine or bicine too), CHES and CAPS. Adding piperidine too may let you get close to 12 (pKa 11.12, range 10.5-12).

If you search by "universal buffer" you will find recipes made to have a linear response to H+ usually from 2-12, though they usually include some inorganic buffers and some components such citrate that may be a C source.

Dear Xabier!

Yes, I asked for organic buffers for some reasons. My colleagues prepared phosphate buffer (see a link below) for cultivation but they are still not sure if only pH value by itself, or also presence of some inorganic ions influence some growth conditions...

And thanks again for your suggestions and support!

There is a lot to think about .

As I realize, there is impossible to prepare completely universal organic buffer... Use of Citrate as a carbon sourse I guess will lead to increase of pH during cultivation (about 2-3 weeks).

Though TRIS-Hepes provide just slight pH range, it also provide stable pH during cultivation period and that is also a great benefit for my tests.

Article Sodiomyces alkalinus, a new holomorphic alkaliphilic ascomyc...

Oh, I see what you mean.

Well, in first case it is well known that at least in some bacteria, the ammounts of P usually added as buffer, exceed way too much the physiological requirements of the organisms and sometimes it is enough with the P traces from the other ingredients to fulfill those needs.

Now, regarding the growth and C-sources. As alkaliphilic organism you may expect a higher growth rate in all the pH 10 media but... we are dealing with extreme pH values and some polysacharides and organic polymers may decompose, at least partially in those conditions. Nonetheless, an alkaline treatment is used to solubilise the more amorphous phase from the fungal cell wall to study the structure, and during the paper manufacturing, the lignin is removed with an alkaline solution and the result is partially hydrolised. This can be an explaination why in some cases the growth is way higher at pH 10.

In some cases, the change in the protonation of chemical species from outside the cells vs. inside. E.g. extreme acidophiles are usually very sensitive to fluoride because outside the cells (pH 2) is found as HF but once it enters in the cell (pH 7), it dissociates to H+ + F- which causes a drop in the cytosolic pH. I don't think is the case here, not with carbohydrates at least as they usually have pKa values of at least 12 and higher. It is a bit complicated to analyse as they use agar plug method for culturing and they carry some foreign medium, that's why I used to do point inoculations when I did growth tests some time ago.

Another option based on the generalised poor/no growth with simple sugars that could be due to a generalised lack of simple sugar transporters, being rich in oligosaccharide transporters intead derived from niche specialization.

And that's all I can come up right now. Hope it helps.

Dear Xabier,

Thank you for information and suggestions!

Can you please recommend me some papers dealt with pH - dependent organic polymer decomposition? I'm familar with these phenomena, but I found very poor information available from microbiologists studied microbal communities of saline  soda soils and lakes...

It's really important point for my study.

I actually barely have experience with alkaliphiles and I'm afraid I might be of little help aside of providing hypothetical scenarios like in my previous message. I've mostly worked with acidophiles and while the effects of extreme pH values can be similar on polysaccharides, meaning that they may degrade, the reaction mechanisms and by-products would be different.

I really wouldn't be able to provide or recommend any literature without searching thoroughly by myself, but it's likely that you may find most of the related contents in papers regarding structural chemistry of carbohydrates. There isn't much about fungi in extreme environments and much less in alkaline habitats. I would suggest to search by polysaccharide alkali hydrolysis or even by the specific polysaccharide.

Thanks, Xabier. The direction for search you provided is a good idea I think!

Reading you last message, I recalled that I found some interesting information on intracellular lipid chemistry examining papers delivered by chemists, at least not by biologists...