Questions regarding carbon base production.

Steve J. Quest Squest at cris.com
Mon Dec 22 14:29:42 EST 1997


On Mon, 22 Dec 1997, Ron Lahav wrote:

> Dear Steve, usually when I make my medium I prepare 2 solutions separately.
> The medium that I use is YPD and the sugar is glucose. I routinely make
> medium at pH of 4 or 5 with no problems whatsoever. One solution is 1%

	How low can one go on pH and be ok?  I want to avoid bacterial
contamination (so I don't have to practice such sterile procedures which
takes up MOST of my time) by making the medium incompatable with bacteria
(low pH) I can be a bit less careful.  I want to try pH of 3, but thought
I'd ask the group as I'm sure others have experience with pH in the medium
and can give me advice.  :) 

> yeast extract and 2% bacto-peptone, and the other is a concentrated stock
> of 40% glucose. The medium I adjust to whatever pH I desire, and when the
> solutions cool down I add the appropriate amount of the 40% stock to reach
> a final concentration of 2%. I see no reason that it shouldn't work with
> sucrose as well.

	I don't use percentages, all the information I have involves the
use of the Brix hydrometer (Saccharometer).  I dilute my stock solution to
18 degrees Brix, which seems to be the best concentration for anaerobic
growth, while I haven't found a concentration for aerobic.  Yeast don't
seem to care how much carbohydrate is present when grown aerobically in my
experience, when grown in inverted sugar solutions that is.  :)

> Cheers, good luck.

	Thank you for your help!  :)

sq

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