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[Yeast] RE: Yeast Digest, Vol 36, Issue 13

Andrew Carter via yeast%40net.bio.net (by cartera from cmp.ucsf.edu)
Mon May 26 12:33:41 EST 2008

This is an interesting discussion....  I was always told that raffinose
tends to break down on autoclaving and that the filtered form was

I was wondering why if sucrose is broken down into glucose and fructose,
why the glucose does not repress the galactose promoter in the same way
that glucose in the media does?  
Best wishes

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Subject: Yeast Digest, Vol 36, Issue 13

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Today's Topics:

   1. Re: Raffinose versus Sucrose (Ilya Soifer)


Message: 1
Date: Mon, 26 May 2008 10:53:11 +0300
From: "Ilya Soifer" <ilya.soifer from gmail.com>
Subject: Re: [Yeast] Raffinose versus Sucrose
To: yeast from magpie.bio.indiana.edu
	<1952757a0805260053h60b91c14x30299960d15dd95c from mail.gmail.com>
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Dear all,
I have a similar question - some labs use autoclaved raffinose and some
filtered raffinose in the media prior to galactose induction.
Does anyone have an idea why and which way is preferrable?
Thanks a lot,

2008/5/24 Daniel Bosch <daniel.bosch from gu.se>:

> Hi Kerry,
> Both sucrose and raffinose are broken up outside of the cell by the
> enzyme, invertase. Sucrose generates glucose and fructose that can be
> immediately transported into the cell and assimilated. Raffinose leads
> fructose and melibiose. The latter is broken up by another enzyme,
> melibiase, which is not present in all lab strains. As a matter or
fact, the
> degradation of raffinose will yield less amount of fermentable sugars
> in lab strains than sucrose (100%) and therefore it can be considered
> poorer carbon source. Neither sucrose nor raffinose should lead to a
> repression of the GAL genes.
> Having said this, I don't know why some labs prefer sucrose over
> or mixtures of both. An alternative to sugars is the use of
> carbon sources, such as glycerol or ethanol. I particular find that
> grow better in a mixture of the two (3% glycerol and 1% ethanol) than
on any
> of them alone.
> Hope this was helpful,
> Dani
> Daniel Bosch
> Postdoc in Nyström's lab
> Dept. Cell and Molecular Biology
> University of Gothenburg
> Sweden
> ------------------------------
> From Kerry Geiler <kgeiler from gmail.com>
> Sent Sat 5/24/2008 12:50 AM
> To yeast from magpie.bio.indiana.edu
> Cc
> Subject [Yeast] Raffinose versus Sucrose
> HI,
> I have a question about whether yeast grow better in sucrose and
> or a combination of both.  I am using galactose induction, so I cannot
> my strains in glucose.  I have inquired with many nearby labs and some
> 2% sucrose, some use 2% raffinose, and some use 2% sucrose, 1%
>  However, none of these labs can tell me why they made this decision
> seems to be a part of their lab culture).  Does anyone know the
> between yeast growth in sucrose vs raffinose?  Do either of these
> inhibit metabolism of the other sugar?  Any information that will
inform my
> decision of which sugar to choose would be greatly appreciated.
> Kerry Geiler
> kgeiler from gmail.com
> ------------------------------
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