stygian
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Ester byproducts of fermentation..
Aside from the obvious ethanol, which can be used as motor fuel (or drunk), how much of other alcohols and esters are produced in comparison to
ethanol alone? I know that the fermentation substrate and strain of yeast could vary by a lot. Could the whole mix of esters and alcohols (e.g.
methyl, isopropyl, butyl, whatever..) be more economical, or benificial in some way?
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Magpie
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n-Butanol can be made by fermentation of corn. I understand that it is an excellent automobile fuel and superior in energy/lb to ethanol. There is a
fair amount of university research being devoted to developing the process to be competitive. University of Illinois at Urbana, IIRC.
I gave some thought to making n-butanol by this route as a home project. The proper bacteria are available cheaply. The trouble is that they require
anaerobic conditions.
The single most important condition for a successful synthesis is good mixing - Nicodem
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not_important
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There are very small amounts of esters produced, under the conditions the yeast (or bacteria) live in ester are 'uphill' energetically and thus take
energy away from the organism. Esters of longer chain fatty acids - oils and fats - are used as energy storage by many organisms.
You will find plenty on the acetone-butanol fermentation, it was used back are WW-I on into the `20s. Isopropanol can also be had, all of these are
bacterial fermentations.
Lactic acid is another fermentation product, bacteria have been the method but I believe there are now strains of acid tolerant yeast that can be
used. Citric acid is another industrial fermentation product.
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Intergalactic_Captain
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Did a little looking into the ABE process as well. Anaerobic conditions would be easy enough, it's the limitations of the bacterium that put me off.
Clostridium Acetobutilicum (and a few other clostridium) only "ferment" out to ~8% total solvent volume, of which butanol is somewhere around a third.
Back before the extensive production of crude-oil derived chemicals, it was economical enough to sell/use the acetone and ethanol to make this a
viable process for n-butanol production...Just not economical enough anymore to dump money into research.
Except for BP, they're apparently doing some research on bio-butanol. It has roughly the same octane rating as gasoline, easily lending itself to
replace the currently used fuel without engine modification or energy-density related issues. Sorry I don't have any ref's, it's been a while since
I looked into this. Google the ABE process or butanol fermentation...Bacterium cultures can be bought from Carolina Biological Supply for around
$8/tube.
Personally, if I were going about turning raw biomass into fuel, I'd look into cellulosic ethanol. The enzymes availible currently are hellishly
expensive, though...Perhaps one could breed the hell out of a sample of some cellulase producing organism and use it for this purpose - Anyone know of
any wild bacteria that could be "captured"?
If you see me running, try to keep up.
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Sauron
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IIRC making higher alcohols by fermentation STINKS (literally).
Methanol is only produced if woody material is present in the mash. And then it is produced in small amounts.
In ethanol fermentation, over-aeration of the mash produces acetic acid and that reacts with ethanol to give ethyl acetate. Normally this is a minor
congener. Aeration is only done in the yeast lag phase; continuing aeration will give only acetic acid. Ethanol fermentation is anaerobic, but
normally a simple air lock (bubbler) suffices as the vast amount of CO2 produced keep internal pressure positive.
2-propanol is manufactured by fermentation I believe.
Sic gorgeamus a los subjectatus nunc.
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chemrox
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2-propanol and cyclopentanone .. there was a Brittish chemist making ketones and alcohols by the carload in WWII. Forget who that was but the story
can be tracked down with a little effort..@Sauron, jump in here if I'm wrong but I think some of the higer alcohols can be made by fermentation under
aerobic conditions.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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triggernum5
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In theory would yeast be just as, or nearly as happy taking oxygen from more obscure componds, perhaps even inorganic in an otherwise anaerobic
solution? Could it liberate it, even if it dies in the process? I guess there is oxygen in the water itself though, so its presence probably answers
the question. Basically I'm wondering how yeast O2 uptake works from a balanced equation POV.. Not the solution side eqn, but how the yeast grabs
the oxygen.. Or failing that, a general idea of the molecular properties/limits required to constitute a sugars/pectins substitute..
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Sauron
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Industrial fermentation of a multitude of organic products is nothing new, it has been around for a long time, and is of considerable importance.
There are entire volumes on the subject, and naturally you can find a lot in works such as Ullmann's and Kirk-Othmer, q.v.
About the use of yeast with inorganic substrates I have no idea.
Sic gorgeamus a los subjectatus nunc.
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not_important
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| Quote: | Originally posted by triggernum5
In theory would yeast be just as, or nearly as happy taking oxygen from more obscure componds, perhaps even inorganic in an otherwise anaerobic
solution? ... |
The yeast isn't just "grabbing the oxygen from compounds" It must utilise ones that it has enzymes to handle, on pathways that lead to net overall
energy production. It seems to be limited to a fairly snall number of organics.
There are bacteria that do well with nitrate or sulfate as their oxygen source. Some can reduce Fe(III), Mn(IV), and other such ions. Some fungi
apparently can reduce Fe(III) and nitrate.
http://biochemie.web.med.uni-muenchen.de/Yeast_Biol/03%20Yea...
http://www.yeastgenome.org/biocyc/
http://www.gwu.edu/~mpb/biochemterms.htm
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Sauron
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One of my former associates is an environmental microbiologist and his specialty is isolating and culturing bacteria that can be employed in
remediation of various sorts of waste problems, from restaurant grease traps to oil spills to whatever. Basically he surveys for naturally occuring
bacteria in the locale of the pill that have mutated to consume whatever was spilled. No genetic engineering involved, except by nature. Once he has
spotted the bug he wants, he then isolates it and makes a lot of it, and applies it to the spill.
I have read patents where desired modifications were induced with mutagens like MNNG. The mutagen just induces mutations randomly, the technicians
then look for the one they want to appear.
Sic gorgeamus a los subjectatus nunc.
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triggernum5
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I actually was aware of the plethora of bacterial fermentaions etc (well, not the inorganic ones, so thanks for that).. Its just that obviously even
Sac. Cerviseae can metabolize many diferent molecules.. After I posted that I realized it must be enymatic, but thats a whole 'complex' realm that I
have no background in as biology was the one science I pretty much skipped in school.. I actually wasn't aware that the yeast contained so many
specific enymes as n_i mentioned.. I guess a good starting gate would be the carb busting A-amylase reaction sinve I have seen info on that alot..
At this point, I just hope somebody can elude to the practical/theoretical scope of enzymes in common yeasts..
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