Fructose-6-phosphate phosphoketolase

E. (1958) Phosphorolytic cleavage of ffuctose-6-phosphate by fructose-6-phosphate phosphoketolase from Acetobacter xylinum. J. Biol Chem., 233 (6), 1283-1288. 

Some lactic acid bacteria of the genus Lactobacillus, as well as Leuconostoc mesenteroides and Zymomonas mobilis, carry out the heterolactic fermentation (Eq. 17-33) which is based on the reactions of the pentose phosphate pathway. These organisms lack aldolase, the key enzyme necessary for cleavage of fructose 1,6-bisphosphate to the triose phosphates. Glucose is converted to ribulose 5-P using the oxidative reactions of the pentose phosphate pathway. The ribulose-phosphate is cleaved by phosphoketolase (Eq. 14-23) to acetyl-phosphate and glyceraldehyde 3-phosphate, which are converted to ethanol and lactate, respectively. The overall yield is only one ATP per glucose fermented. 

Fig. 1-4A). Heterofermenters, however, lack the enzyme fructose-diphosphate aldolase and must divert the flow of carbon through the 6-phospho-gluconate pathway (pentose phosphate or phosphoketolase pathway) as depicted in Fig. l-4b to yield lactic acid as well as ethanol, acetic acid (depending on redox potential), and CO2. Energetically, the consequence of only half of the carbon returning to the EMP is formation of 1 mole of ATP/glucose.

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