Microbial Metabolism of Food Components  ◾  83
EMP Pathway
The EMP pathway is used by homofermentative lactic acid bacteria, Enterococcus faecalis, Bacillus
spp., and yeasts (Figure 8.1). Other hexose monophosphates enter the EMP pathway at different
steps, mostly before fructose diphosphate.
HMP Pathway
The HMP pathway is also called the HMP shunt, pentose cycle, or Warburg–Dickens–Horecker pathway (Figure 8.1). It is used by heterofermentative lactic acid bacteria, Bacillus spp., and Pseudomonas
spp. Ribose phosphate can be used for the synthesis of ribose and deoxyribose moieties in nucleic acids.
Entner-Doudroff (ED) Pathway
The ED pathway is used by Pseudomonas spp.
Glucose phosphate Phosphogluconate Pyruvate Gly
→
→
+
c ceraldehyde phosphate
Pyruvate Acetaldehyde Eth
→
→
a anol
CO
↓
2
Glyceraldehyde phosphate Pyruvate Acetaldehyde
→
→
→ E Ethanol
CO
↓
2
EMP pathway
HMP pathway
Glucose phosphate
Phosphogluconate
Ribulose phosphate
CO 2
Ribose phosphate
Lactate
Acetyl phosphate + Pyruvate
Acetate or ethanol
Ethanol
Acetaldehyde
Alcohol
fermentation
Lactate
fermentation
Fructose phosphate
2 Pyruvate
Glucose phosphate
Lactate
CO 2
Figure 8.1 the embden-Meyerhoff-Parnas (eMP) pathway and the hexose monophosphate
shunt (HMP) pathway.