A thought on CO2 production with yeast

McJosh13

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Nov 17, 2004
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CO2 production with yeast and H2O2

A chemistry experiment I did yesterday in CHM Lab has got me thinking about one of the major limitations of producing CO2 with yeast and a possible way to solve it. In our coke bottles filled with yeast, water, and sugar, the yeast is producing CO2 anaerobicaly (without oxygen) with a by-product of ethanol (alcohol) which ultimately kills the yeast. In aerobic respiration (with oxygen) no ethanol is produced and more CO2 is produced. You would theoretically never have to change the contents of your coke bottle, just add more sugar when it runs out.

In lab we were producing O2 by adding hydrogen peroxide (H202) to yeast which catalyzes the following reaction thru the enzyme catalase

2(H202)-------------->2(H20)+O2

Producing water and oxygen. If one were to add some hydrogen peroxide to their sugar and yeast solution, O2 would be produced for some time increasing CO2 production and preventing the production of ethanol.
Thoughts on this are welcome!

Here is some further info
http://www.purchon.com/biology/respire.htm
"The most efficient form of respiration is aerobic respiration: this requires oxygen. When oxygen is not available, some organisms can respire anaerobically i.e. without air or oxygen. Yeast can respire in both ways. Yeast gets more energy from aerobic respiration, but when it runs out of oxygen it does not die. It can continue to respire anaerobically, but it does not get so much energy from the sugar. Yeast produces ethanol (alcohol) when it respires anaerobically and ultimately the ethanol will kill the yeast."

http://www.sciencebuddies.org/mentoring/project_ideas/MicroBio_p009.shtml
"Yeast can extract more energy from sugar when oxygen is present in their environment. In the absence of oxygen, yeast switch to a process called fermentation. With fermentation, yeast can still get energy from sugar, but less energy is derived from each sugar molecule.

In addition to deriving less energy with fermentation, the end products of sugar metabolism are also different. When oxygen is present, the sugar molecules are broken down into carbon dioxide and water (plus the energy that the yeast uses to grow and reproduce). In the absence of oxygen, the fermentation process produces alcohol, carbon dioxide and water (and less energy)."
 
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Good thinking and excellent use of your newly acquired knowledge from class.

But the point is to produce a concentrated stream of CO2, which you won't be able to achieve if you are bubbling oxygen into your yeast.

Bottled oxygen that would be necessary is expensive, and you might as well just go with bottled CO2 if you are going to buy the regulators and commit to refilling gas cylinders from time to time.

Sure, the yeast can work more efficiently under aerobic conditions, but sugar is cheap.

The idea to use hydrogen peroxide would produce some oxygen, but that oxygen would be expensive compared to sugar.
 
If i understand him correctly he intends on adding hydrogen peroxide to the yeast mix - and not bubble oxygen into it. Am i wrong ?
 
Hannys_Papa said:
If i understand him correctly he intends on adding hydrogen peroxide to the yeast mix - and not bubble oxygen into it. Am i wrong ?
That's how I read it, too.

Gonna try it just for a hoot in a fishless tank (just in case) :) Peroxide is a buck a small bottle. Cheap experiment.

Roan
 
Exactly, I am just adding some hydrogen peroxide to the yeast mix. The amount to add and how long it will last can only really be determined after some experimentation.
 
The only thing that cautions me about experimenting with this is the build up of pressure caused by so many gases.

I'm actually going to try it with the jello recipe. Since there is no huge initial burst of CO2 as there is with just sugar and water, I think it would work better that way. Not as much sudden gas buildup either.

Roan
 
RTR, whatcha think?
 
I haven't told my husband.

If I did, he wouldn't let me do it :D

I'm gonna keep the bottle in the kitchen in the cupboard so that if something happens I'll just have some wood damage and fermented jello to clean up :)

Roan
 
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