MICROBIAL METABOLISM CONTD....

ED PATHWAY ( ALTERNATIVE TO GLYCOLYSIS)
   Although the glycolytic pathway is the most common route for the
conversion of hexoses to pyruvate, another pathway with a similar
role has been discovered. The Entner-Doudoroff pathway begins
with the same reactions as the pentose phosphate pathway, the formation
of glucose 6-phosphate and 6-phosphogluconate .Instead of being further oxidized, 6-
phosphogluconate is dehydrated to form 2-keto-3-deoxy-6-
phosphogluconate or KDPG, the key intermediate in this pathway.
KDPG is then cleaved by KDPG aldolase to pyruvate and glyceraldehyde
3-phosphate. The glyceraldehyde 3-phosphate is converted
to pyruvate in the bottom portion of the glycolytic pathway.
If the Entner-Doudoroff pathway degrades glucose to pyruvate in
this way, it yields one ATP, one NADPH, and one NADH per glucose
metabolized.


Most bacteria have the glycolytic and pentose phosphate
pathways, but some substitute the Entner-Doudoroff pathway for
glycolysis. The Entner-Doudoroff pathway is generally found in
Pseudomonas, Rhizobium, Azotobacter, Agrobacterium, and a few
other gram-negative genera. Very few gram-positive bacteria have
this pathway, with Enterococcus faecalis being a rare exception.

                                                 Fig: Entner- Doudoroff Pathway 

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