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 Re: Yeast Digest, Vol 45, Issue 3
Hi all, A related question: are raffinose and galactose fermentable carbon sources? I read somewhere that they are "poorly fermentable" and when looking at the lipid profiles, I suspect that they are not fermenting. Is this true, cause in theory they are sugars and should be fermentable.
Kind regards, Cedric On Fri, Feb 6, 2009 at 6:05 PM, <yeast-request@...> wrote:
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Today's Topics:
1. Re: RE: Yeast Digest, Vol 45, Issue 1 (Daniel Bosch)
2. RE: Yeast Digest, Vol 45, Issue 2 (Shaoyu Wang)
----------------------------------------------------------------------
Message: 1
Date: Thu, 5 Feb 2009 19:01:22 +0100
From: "Daniel Bosch" <d_bosch@...>
Subject: Re: [Yeast] RE: Yeast Digest, Vol 45, Issue 1
To: <yeast@...>, <yeast@...>
Message-ID: <BLU110-DS1FF211F56C51903C3CA5C81C00@...>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Hi there,
Baker's yeasts loves glucose and fructose, these are consumed earlier than
any other carbon source present in the medium. Uptake and degradation of
galactose (and other respiratory carbon sources) is not functional for as
long as glucose is available. Therefore, to get the GAL promoter to work
glucose mustn't be present. That's why yeast are grown on raffinose, but in
principle you could used cheaper carbon sources (e.g. maltose, ethanol,
acetate). Glucose fermentation yields more energy per unit of time than
galactose or raffinose, hence glucose allows the fastest growth rate. In
addition, during glucose growth a large portion of the genome is repressesed
saving energy, therefore glucose yields a higher OD than other carbon
sources.
Hope this helps you,
Daniel Bosch
--------------------------------------------------
From: "Andrew Carter" <cartera@...>
Sent: Wednesday, February 04, 2009 6:27 PM
To: <yeast@...>; <yeast@...>
Subject: [Yeast] RE: Yeast Digest, Vol 45, Issue 1
> Hi Thomas
> Glucose represses the Gal promoter whereas Raffinose doesn't. If you try
> growing up yeast in YPD (2% glucose) and then add galactose you will get
> no
> (in my experience) induction. If you grow up in YP raffinose and add
> galactose the promoter will get turned on immediately.
>
> It turns out however that you can first grow in glucose and then add
> galactose. You just have to make sure that you have used up all your
> glucose. I have been playing with this quite a lot recently (in a large
> fermentor) and it works well. The key for me was using 2X YP and 1%
> glucose
> and waiting until growth plateaus. Then add in 2% galactose (0.5% and 1%
> also work) and induction turned on just fine. I was using induction from
> a
> gal promoter inserted in the genome and haven't tried it with a plasmid
> based system, but my guess is it should work. The real advantage is that
> Raffinose gets really expensive if you want to scale up...
>
> Not sure why growth is slower in galactose than glucose but I see it alot
> (final OD is usually lower as well).
> Best wishes
> Andrew
>
>
>
>
>
>
> -----Original Message-----
> From: yeast-bounces@...
> [mailto:yeast-bounces@...] On Behalf Of
> yeast-request@...
> Sent: Wednesday, February 04, 2009 9:06 AM
> To: yeast@...
> Subject: Yeast Digest, Vol 45, Issue 1
>
> Send Yeast mailing list submissions to
> yeast@...
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://www.bio.net/biomail/listinfo/yeast
> or, via email, send a message with subject or body 'help' to
> yeast-request@...
>
> You can reach the person managing the list at
> yeast-owner@...
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Yeast digest..."
>
>
> Today's Topics:
>
> 1. raffinose metabolism (Thomas, Arun)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 4 Feb 2009 11:36:10 +0100
> From: "Thomas, Arun" <Arun.Thomas@...>
> Subject: [Yeast] raffinose metabolism
> To: <yeast@...>
> Message-ID:
>
> <F69C1DF9630D414E9411B4CB41240ABD0B12E6@...>
>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi everyone,
>
> To induce a gene under the GAL promoter from a 2micron plasmid, why is it
> preferred to grow the cells in raffinose/glucose initially followed by
> induction with galactose?
>
> If cells grow slowly in galactose, why is it so?
>
> Thank you,
> Thomas
>
>
>
> ------------------------------
>
> _______________________________________________
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> End of Yeast Digest, Vol 45, Issue 1
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------------------------------
Message: 2
Date: Fri, 6 Feb 2009 06:09:39 +1100
From: "Shaoyu Wang" <S.Wang@...>
Subject: [Yeast] RE: Yeast Digest, Vol 45, Issue 2
To: <yeast@...>
Message-ID:
<FB4F123E1A1345488DC47F54B1259236017B65FF@...>
Content-Type: text/plain; charset="iso-8859-1"
Hello, Everyone,
FCY2 gene is an important purine-cytosine permease. However, there two more putative purine-cytosine permeases encoded by FCY21 and FCY22. But there is lack of information on exact substrates and regulation of their activity etc. Only information I get is: Fcy21p and Fcy22p are very similar to Fcy2p but can not substitute its function.
I wonder if anyone have more information on FCY21 and FCY22 and their protein product functions. Any pointers are appreciated.
Thank you
Shaun
________________________________
From: yeast-bounces@... on behalf of yeast-request@...
Sent: Fri 6/02/2009 4:06 AM
To: yeast@...
Subject: Yeast Digest, Vol 45, Issue 2
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----------------------------------------------------------------------
Message: 1
Date: Wed, 4 Feb 2009 09:27:26 -0800
From: "Andrew Carter" <cartera@...>
Subject: [Yeast] RE: Yeast Digest, Vol 45, Issue 1
To: <yeast@...>, <yeast@...>
Message-ID: <000001c986ed$daa298f0$8fe7cad0$@ucsf.edu>
Content-Type: text/plain; charset="us-ascii"
Hi Thomas
Glucose represses the Gal promoter whereas Raffinose doesn't. If you try
growing up yeast in YPD (2% glucose) and then add galactose you will get no
(in my experience) induction. If you grow up in YP raffinose and add
galactose the promoter will get turned on immediately.
It turns out however that you can first grow in glucose and then add
galactose. You just have to make sure that you have used up all your
glucose. I have been playing with this quite a lot recently (in a large
fermentor) and it works well. The key for me was using 2X YP and 1% glucose
and waiting until growth plateaus. Then add in 2% galactose (0.5% and 1%
also work) and induction turned on just fine. I was using induction from a
gal promoter inserted in the genome and haven't tried it with a plasmid
based system, but my guess is it should work. The real advantage is that
Raffinose gets really expensive if you want to scale up...
Not sure why growth is slower in galactose than glucose but I see it alot
(final OD is usually lower as well).
Best wishes
Andrew
-----Original Message-----
From: yeast-bounces@...
[mailto:yeast-bounces@...] On Behalf Of
yeast-request@...
Sent: Wednesday, February 04, 2009 9:06 AM
To: yeast@...
Subject: Yeast Digest, Vol 45, Issue 1
Send Yeast mailing list submissions to
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of Yeast digest..."
Today's Topics:
1. raffinose metabolism (Thomas, Arun)
----------------------------------------------------------------------
Message: 1
Date: Wed, 4 Feb 2009 11:36:10 +0100
From: "Thomas, Arun" <Arun.Thomas@...>
Subject: [Yeast] raffinose metabolism
To: <yeast@...>
Message-ID:
<F69C1DF9630D414E9411B4CB41240ABD0B12E6@...>
Content-Type: text/plain; charset="iso-8859-1"
Hi everyone,
To induce a gene under the GAL promoter from a 2micron plasmid, why is it
preferred to grow the cells in raffinose/glucose initially followed by
induction with galactose?
If cells grow slowly in galactose, why is it so?
Thank you,
Thomas
------------------------------
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