Roberto Carlos wrote:
>> I am interested in how fast Escherichia Coli can metabolize Hexoses
> (esspecially glucose and fructose) and the ammount of end products.
>> As far as I seem to know, E.Coli ferments Glucose and fructose to H2
> and CO2, richt?
>> Now the question is, how much glucose or fructose can one single E.Coli
> ferment in one minute?
> I know one E.Coli can not ferment very much but I just need a number to
> calculate how many E.Coli are needed to ferment 1 mol of glucose or
> fructose in one hour.
Well, you seem to be starting with some assumptions that aren't
necessarily true. When you say "metabolizes," are you only referring
to fermentation? E. coli can also utilize hexoses during aerobic and
anaerobic respiration, and it uses them at a much faster pace (because
both types of respiration allow more energy production, and hence,
Also, the end products of glucose fermentation vary depending on the
growth conditions....in particular, on the pH of the medium. During
acidic conditions, E. coli produces lactate (lactic acid), while during
more neutral conditions, it produces ethanol, acetate (acetic acid),
and formate (formic acid), which breaks down to CO2 and H2.
So, I guess to answer your question, you're going to have to be a
little more specific. Another problem is in how one goes about
measuring the metabolism of one single bacterium. I'm not sure how you
can measure this, because as bacteria metabolize, they also grow and
divide. So, how one is able to determine the contribution of one
bacterium to the degradation of a given amount of sugar in a culture of
several trillion bacteria (that are all also actively dividing) gets
pretty tricky. I'm not saying it can't be done, but I certainly don't
know how. (How does one prevent bacteria from dividing, yet allow them
to grow and metabolize? Better yet....how does one grow up a culture
of said mutant, if by definition, it can't divide?)
Maybe someone else has a better answer.....or already knows the answer?
Alex B. Berezow, Grad Student
Dept. of Microbiology
University of Washington School of Medicine
Seattle, WA 98195