How does yeast count/assess sugars in the wort during adaptation-phase?

[Keiron]

Does anybody know the mechanics behind this?

I can't find any material that goes into depth on this subject. It's always simply stated that the yeast "takes stock of the sugars" and reproduce a sufficient number of cells according to the amount of sugars.
If you underpitch, the yeast buds (too)many times trying to handle all the sugars, resulting in scars in the membrane and generally weak/stressed yeast.

BUT, how does the yeast "count" the sugars, and how is this communicated among the cells that they are now a sufficient amount, and can start eating sugars? I don't get it...

I have one thory, based on nothing but a guess: Some kind of substance is excreted from the cells from each budding, and when the ratio of this substance and the sugars in the wort is right, the attenuative phase can start.

 

[podz]

All fungi are able to communicate amongst themselves, but the mechanism is not yet scientifically understood.

On top of that, plants are also able to use the fungi to transmit messages to one another. For example, if one rose bush starts to get attacked by aphids, it sends out a broadcast warning and the other rose bushes in the vicinity begin to excrete chemical countermeasures. We know that it happens, i.e. that the messages use the underground fungal mycelium as transport, but do not yet understand how it happens.

 

[suregork]

If you are interested in scientific literature on the subject, then here is a recent review on nutrient sensing and signaling in yeast:

http://femsre.oxfordjournals.org/content/38/2/254.long

It should be open access, if not send me a message and I'll send you a pdf copy.

 

[Keiron]

That is very interesting. Thank you for the link, suregork. It works like a charm and it seems as though it contains the info I was looking for.

I will try to read it some time this week and do my best in understanding the content and report back with my conclusions.

By the way, the reason I am so curious about this is regarding mixing yeast strains. See this thread for some background-info.

For example, what happens if you pitch a 50/50 lager/ale mix at det same time, and the mechanisms for nutrient sensing is specific to each strain, e.g they communicate on different frequencies?? Will both strains "think" they are undermanned, and duplicate to the point of getting stressed, even though in reality, it was a healthy pitch?