Microbial Metabolism

LECTURE 10:

Microbiology and Virology; 3 Credit hours

Atta-ur-Rahman School of Applied Biosciences (ASAB)National University of Sciences and Technology (NUST)

ATP

Interesting Fact

• ATP is continuously recycled in organisms: the human body, which on average contains only 250 grams of ATP, turns over its own body weight equivalent in ATP each day.

• The collective metabolic capacities of bacteria allow them to metabolize virtually every organic compound on this planet.

Substrate level phosphorylation

Sugar Metabolic Network in Bacteria

Amphibolic Pathway

THE BREAKDOWN OF GLUCOSE TO PYRUVATE

• Microorganisms employ several metabolic pathways to catabolize glucose and other sugars– The Embden Meyerhof pathway, – The pentose phosphate pathway, and– The Entner Doudoroff pathway

• These three pathways are collectively called as glycolytic pathways or as glycolysis

Glycolytic Pathway

Stage 1

Stage 2

The

Embd

en M

eyer

hof p

athw

ay

Stage 1

Triose phosphate isomerase

Glyceraldehyde 3 phosphate dehydrogenase

Phospho glycerate kinase

Phosphoglycerate mutase

Enolase

Pyruvate Kinase

Stage 2

The Pentose Phosphate Pathway

The Pentose Phosphate Pathway Importance in Biosynthesis

• NADPH from the pentose phosphate pathway serves as a source of electrons for the reduction of molecules during biosynthesis

• Two important precursor metabolites:– erythrose 4-phosphate, which is used to synthesize

aromatic amino acids and vitamin B6 (pyridoxal) – and ribose 5-phosphate which is a major component of

nucleic acids.• Hexose sugars needed for peptidoglycan synthesis

The Entner Doudoroff Pathway

KDPG aldolase

This pathway yields one ATP, one NADPH, and one NADH per glucose metabolized