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[Yeast] Raffinose versus Sucrose

Ilya Soifer via yeast%40net.bio.net (by ilya.soifer from gmail.com)
Mon May 26 02:53:11 EST 2008

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 same
> enzyme, invertase. Sucrose generates glucose and fructose that can be
> immediately transported into the cell and assimilated. Raffinose leads to
> 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 (33%)
> in lab strains than sucrose (100%) and therefore it can be considered a
> poorer carbon source. Neither sucrose nor raffinose should lead to a major
> repression of the GAL genes.
> Having said this, I don't know why some labs prefer sucrose over raffinose
> or mixtures of both. An alternative to sugars is the use of respiratory
> carbon sources, such as glycerol or ethanol. I particular find that cells
> 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 raffinose
> or a combination of both.  I am using galactose induction, so I cannot grow
> my strains in glucose.  I have inquired with many nearby labs and some use
> 2% sucrose, some use 2% raffinose, and some use 2% sucrose, 1% raffinose.
>  However, none of these labs can tell me why they made this decision (it
> seems to be a part of their lab culture).  Does anyone know the differences
> between yeast growth in sucrose vs raffinose?  Do either of these sugars
> inhibit metabolism of the other sugar?  Any information that will inform my
> decision of which sugar to choose would be greatly appreciated.  Thanks!
> Kerry Geiler
> kgeiler from gmail.com
> ------------------------------
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