Ask A Scientist Molecular Biology Archive

name         Lylanie P.
status       student
age          17

Question -   How come some bacteria can carry out complete oxidation
of glucose in the absence of oxygen,i.e., anaerobic respiration? So, what
is the " minimal biochemical mechanism" in order for this to be possible?
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Dear Lylanie,

Biochemically speaking, glucose cannot be completely oxidized in the 
absence of oxygen.  Aerobic respiration is required to extract the maximum 
biological reducing energy from glucose.  However, although it does sound 
contradictory, glucose can be partially oxidized by glycolysis under 
anaerobic conditions.  Chemical oxidation does not necessarily require the 
direct presence of oxygen itself, although it certainly can accelerate the 
process.  It simply requires electron transfer from one molecule, which is 
then considered to be "oxidized", to another, which is then considered to 
be "reduced".

Consequently, "the 'minimal biochemical mechanism' in order for this to be 
possible" would be the glycolytic pathway, which is present in all living 
organisms.  Both anaerobic and aerobic glucose metabolism are nicely 
described & diagrammed in the chapter on Cellular Metabolism and 
fermentation from the "On-Line Biology Book":

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookGlyc.html

Hope that this helps to answer your question,

Jeff Buzby, Ph.D.
Children's Hospital of Orange County

NEWTON AAS
Div. of Educational Programs
Argonne National Laboratory
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