CARTENOIDS OF PHOTOSYNTHETIC BACTERIA 



27 



TOTAL C A ROTE NO ID 



50 



• OH-SPHEROiDENONE(OH-R) 



- -O OH-SPHEROiDENE(OH-Y) 



'o/ 



■O 



_._#P518 

 -O SPlRILLOXANTHJN 



SPHEROIDENONE (R) 

 -OSPHEROiDENE(Y) 



25 Time ri hours 



Fig. 3. The influence of air on the carotenoids in a resting cell suspension of 

 anaerobically grown Rhodopseudomoiias gclatiiiosa. Incubated at 30°C in light. 

 From ref. (29). 



Also the interconversions from neurosporene and spheroidenone to 

 P518 observed in aerated cell suspensions represent an extension of 

 the scheme earlier suggested by us (7,23) for carotenoid biosynthesis 

 in Athiorhodaceae, Evidence has been obtained demonstrating that the 

 last-mentioned transformations from spheroidenone can also take place 

 under anaerobic conditions (29). 



As indicated by the carotenoid composition (Table 4) of cells grown 

 with various degrees of aeration, definite transformations occurred 

 on the introduction of air to a washed cell suspension of anaerobically 

 grown cells, incubated in buffer solution in the light. The results of 

 such an experiment are presented in Fig. 3, It is seen that the total 

 carotenoid content remains approximately constant. The decrease in 

 the concentration of OH-spheroidene broadly equals the increase in 



