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Low Phosphate Media?

Marc Lamphier bxg00676 at niftyserve.or.jp
Fri Oct 13 10:44:42 EST 1995

In article <45bm1h$t1c at mark.ucdavis.edu>, szmazer at chip.ucdavis.edu
(Jonathan Mazer) wrote:

> Dear Yeast Researchers,
>      I would like to radiolabel yeast cells with 32-P phosphate. I have 
> seen references to low phosphate media in the literature, but I can't 
> seem to find it in the catalogs. I am using YNB in a SR media. Difco says 
> that they don't have anything more specific. 
>      What are people using for low phosphate media and where can I buy 
> some? 
>      Thank you very much in advance,
>      Jonathan Mazer (jsmazer at ucdavis.edu)

Phosphate can be depleted from any yeast media as follows:

1) Prepare and autoclave 1.5X media without sugar

2) add 1/100th volume of ammonium hydroxide (NH4OH) and magnesium sulfate
(MgSO4) to a final concentration of 10mM

3) stir for 15 minutes, phosphates will form a heavy precipitate

4) filter mixture through Whatman filter paper, and re-filter though 0.45
		millipore-type filter

5) since the ammonium hydroxide makes the mixture highly alkaline the pH
must be adjusted using HCl or other appropriate strong acid (well, don't
use phosphoric acid) to the standard yeast media pH, typically pH 5.5

6) add water to bring final media concentration to 1X

7) re-sterilize by autoclaving again or filtration

8) add sugars and other supplements

This method is adapted from Rubin, 1974 (I don't have exact reference) 

Marc Lamphier
Faculty of Immunology
School of Medicine
University of Tokyo
7-3-1 Hongo, Bunkyo-ku
Tokyo, 113, Japan

lamphier at po.infosphere.or.jp

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