Notes the Natural History of Rhodopseudomonas palustris 583 



TABLE 2 



Effect of Products of Folic-catalyzed Reactions on the 



p-aminobenzoic acid requirement of 



Rhodopseudomonas palustris 



Additions^ to Basal Medium* 

 PABA ABC 



of facultative aerobic purple bacteria showed that utilization of 

 aromatic substrates such as benzoate is widespread among the 

 Athiorhodaceae. 



Manometric experiments were done with resting cells of 

 R. palustris and R. rubrum grown on benzoate-containing media 

 under anerobic conditions in light oxidized benzoate. The O2 

 consumed was proportional to the amount of aromatic substrate 

 (Fig. 1). There was no induction period, which can be taken as 

 evidence that these cells adapted to benzoate during anaerobic 

 photosynthesis. Cells previously grown on substrates such as 

 acetate or glucose require a period of adaptation before attacking 

 benzoate. 



For benzoate to be completely oxidized to COj and H2O, 

 each t'M of substrate requires 168 ml or 7.5 /-M of d. Only 112 

 Acl or 5 /.'M of Oj//'M of benzoate were consumed, which sug- 

 gested that some additional substrate was assimilated. 



DISCUSSION 



Anaerobic enrichment cultures with benzoate, instead of 



