graham wrote:
>> Roy: have you seen the following article?
> Graham
>
> Nature 434, 636 - 640 (31 March 2005); doi:10.1038/nature03405
>
>
>
> Sex increases the efficacy of natural selection in experimental yeast
> populations
>
>
> Why sex evolved and persists is a problem for evolutionary biology,
> because sex disrupts favourable gene combinations and requires an
> expenditure of time and energy. Further, in organisms with
> unequal-sized gametes, the female transmits her genes at only half
the
> rate of an asexual equivalent (the twofold cost of sex

No I based my premises on a monograph by T. Deak a renowned Hungarian
scientist in Budapest University who was devoted so much time to yeast
research.He authored a specialized book which was a comprehensive
study of that particular yeasts that is related to spoilage: T. Deak
and Beuchat I.R.(1995) Handbook of food spoilage yeast. CRC press Boca
Raton Florida.
Incidentally the Saccharomyces cerevesieae is classified both as
beneficial and spoilage yeast!
>From his studies I learned that there are two kinds of yeast
according to how they propagate:
The teleomorph( perfect ) which can sporulate due to sexual
reproduction and the anamorph( imperfect) which can only multiply by
budding.
Now as applied to Sourdough yeast known as Candida milliere( the likely
sporulating form (or teleomorph) but which can co-exist in tandem with
lactobacillus Brevis var Lindniere mostly in the imperfect state or
anamorphic form called as torulopsis holmii
According to Dr. Deak, yeast are classified primarily by their mode of
sexual reproduction , i.e, sporulation which is characteristics of the
saccharomyces species;.It forms spores by conjugations of the opposite
mating type and spores develop after meiotic( formation of egg and
sperm) division of diploid cells( or one chromosome per mating type)
and form a sporangium.( or spore sac)..
Other forms of yeast multiply by budding .And this propagation methods
adds complication to the nomenclature like for example the
Saccharomyces Exiguus which is another name for Torulopsis holmii and
candida milliere. That is why even in this particular area the
nomenclature is hazy and evolving and if they want to understand the
differences they have to refer to older forms of classification.
This also what makes saccharomyces cereviseae term confusing?
The tamed or cultured ones are also classified under this name as well
as the wild yeast that is responsible for food spoilage and other forms
of non fastidious behavior with regards to substrates.
Therefo
There is a specific or highly selective culture media used in
isolating the desired saccharomyces which is beneficial for the food
industry and even the wild yeastin order to identify and confirm its
presence.

So if anybody says that this particular name is just bakers yeast he or
she is wrong.
Roy