Fungi and fermentation

[Sinead Ryan]

how exactly do fungi activate fermentation and is there any particular type or is it just any fungi???
please help
Sinead

[MrMistery]

I suppose you are talking about alcoholic fermentation. Well, it is done by Saccharomyces cerivisiae and Saccharomyces elipsoideus. Activation? Simple: when there is no oxygen in the environment they degrade piruvic acid into ethanol. Also remember that if there is oxygen in the environment they do respire aerob(1 glucose-->38 ATP)
Regards,
Andrew

[Sinead Ryan]

ok thanks, that makes it a bit clearer but still have a few questions.... Piruvic acid?? is that the acid that would be present in the fruits??? and is there a common (and easier to spell) name for Saccharomyces cerivisiae and saccharomyces elipsoideus??

[DevGrp]

try "Pyruvic Acid" or pyruvate which, in low oxygen conditions, instead of entering the citric acid cycle (which requires oxygen) is converted into ethanol (in yeast) or lactate (in humans).

A common name for Saccharomyces cerevisiae is brewers or bakers yeast.


Saccharomyces ellipsoideus apparently http://brewery.org/library/sake/techpa12.htm is the yeast more usually found in wine fermentation. I'd never heard of it before. learn something new every day.

[MrMistery]

Glucose is first degraded without the use of oxygen in the citoplasm into 2 molecules of pyruvic acid. pyruvic acid, if there is oxygen enters the Krebs cycle or citric acid cycle. If there is no oxygen in the environment than yeasts degrede pyruvic acid into ethanol and co2 with the production of 2 molecules of ATP. You will NEVER find pyruvic acid in fruits: that is citric acid and ascorbic acid(vitamin C).
Saccharomyces cerivisiae: beer yeast
Saccharomyces ellipsoideus: wine yeast
Sorry for calling them in latin, it is a bad habit

[Sinead Ryan]

"Glucose is first degraded without the use of oxygen in the citoplasm into 2 molecules of pyruvic acid."

this may sound a very a stupid question but where does the glucose that is turned into pyruvic acid come from???

[Poison]

don't you eat glucose with foods? It enters the cell and then the process starts.

[MrMistery]

Glucose enters the cell through a process called endocitosys. Now it can come from food(animals) or photosynthesis(plants).

[Sinead Ryan]

so the glucose is present in the cells of the fruit??? Sorry i'm very easily confused!!!

[MrMistery]

Glucose is present practically anywhere everywhere. Only in special conditions does you body catabolise fats and in even more special conditions proteins
Now, what you need to know is how sugars are stored: Glucose and fructose are found in fruits, in the sweet juices. In most plants sugars are also deposited unde the form of starch(amidin) cristals-like wheat or potatos. The animal body does not create starch, it stores sugars as glycogen(also refered to as animal starch, however this is kind of incorect). If all the space is taken and it can not turn any more sugars into glycogen it turns them into fats and you star to put on weight
ARe things more clear now?

[Sinead Ryan]

So the glucose (along with fructose) is found in the jucies of the fruit, then is turned into two molecules of pyruvic acid, and then eith beer or wine yeasts act on the pyruvic acid turning it to ethenol and giving off CO2....
That about right???

[MrMistery]

Yes, but the transformation from glucose into 2 molecules of pyruvic acid takes place also in the cell of the yeast. The process is called glycolisis and is very complex. But i think that is all you need to know