THE ACETIC ACID BACTERIA 13 



manometrically (by the cell-free extract), the CO2 produc- 

 tion lagged initially, compared to the Oo consumption. 

 Chromatogiaphy of the oxidation products revealed zones 

 corresponding to 6-phosphogluconate and ribose-5-phos- 

 phate. Both DPN and TPN appeared active in the dehy- 

 drogenases for glucose-6-phosphate and 6-phosphogluconate 

 (see Table 1.4). 



The transketolase-transaldolase reactions that characterize 

 the pentose cycle were demonstrated by chromatography 

 and the appropriate color reactions. Sedoheptulose was 

 determined by the cystine-sulfuric acid reaction, at 415 lUfi 

 and 505 uifx, and ribose was measured with orcinol. Sedohep- 

 tulose and the phosphates of fructose, glucose, and dihy- 

 droxyacetone were also measured chromatographically. 

 The recovery of total sugar and the measurement of each 

 sugar derivative with time is shown in Table 1.5, where 

 ribose-5-phosphate is added non-oxidatively to the cell-free 

 extract and its rate of disappearance is followed together 

 with appearance of other sugars. 



Other ancillary reactions leading into the pentose cycle, 

 such as kinases for ribose, erythritol, and glucose, have been 

 identified. The glucokinase has been partly purified (19). 



Each reaction of the pentose cycle, plus related ones listed 

 in Fig. 1.4, has thus been documented in soluble extracts 

 of the organism. The quantitative importance of the pen- 

 tose cycle as a terminal respiratory mechanism in A. suh- 

 oxydans has been demonstrated (23) through the use of 

 specifically C^Mabeled glucose and gluconate as substrates 

 for aerated resting cells: for every 100 molecules admin- 

 istered 28 were oxidized to 2-ketogluconate, presumably 

 by the particulate dehydrogenases. Of the remaining 72, 

 63 (equals 88%) entered the pentose cycle. As a later 

 chapter will reveal, we have calculated that essentially all 



