74 Perspecfives in Microbiology 



siderable evidence that glucose-6-phosphate and 6-phos- 

 phogluconate are involved, and the mechanism may be 

 similar to the hexose monophosphate shunt mechanism in 

 yeast. 



The 2-KetOj 3-Desoxy, 6-Phospho gluconate Pathway. 

 One of the best understood nonglycolytic mechanisms of 

 glucose decomposition is that discovered in Pseudomonas 

 saccharophila by Doudoroff and his associates. This organ- 

 ism is an obligate aerobe that normally oxidizes glucose to 

 carbon dioxide without appreciable accumulation of inter- 

 mediate products. Entner and Doudoroff (4) showed, how- 

 ever, that in the presence of suitable inhibitors (DNP and 

 arsenite), cell suspensions oxidize either glucose or gluco- 

 nate with the accumulation of two moles of pyruvate. A 

 tracer experiment with glucose- 1-C^* showed that the car- 

 boxyl group of pyruvate is derived in part from carbon 



GLUCOSE •COOH •COOH •COOH 



CHOH C=0 C=0 



I i I 



GLUC0SE-6-P'-^CH0H — > CHg — CH3 



CHOH CHOH CHO 



CHOH CHOH CHOH 



I I I 



CH2O-P CH2O-P CH2O-P 



6PHOSPHO- 2KET0,3DES0XY, PYRUVATE 



GLUCONATE 6PH0SPH0 GLU- + 



CONATE TRIOSE 



PHOSPHATE 



FIGURE 5. Pseudomonas saccharophila Pathway of Glucose Oxidation, 

 after MacGee and Doudoroff (15) 



atom 1 of glucose. Further enzymatic studies established 

 that glucose is first phosphorylated and then oxidized to 

 phosphogluconate. MacGee and Doudoroff (15) have shown 

 that the latter compound undergoes an enzymatic rear- 

 rangement to yield a new compound, which has been iso- 



