METABOLIC ASPECTS OF BACTERIAL 

 PHOTOS YNTHESISl 



HOWARD GEST 



The Henry Sliaiv School of Botany and the Adolphus Busch III Laboratory 



of Molecular Biology 



Washinsion Universitv, St. Louis, Missouri 



The overall metabolism of photosynthetic bacteria is clearly dis- 

 tinguished from that of green plants in at least two particular respects 

 (Table 1). These properties have been known for many decades and 

 much effort has been expended in obtaining evidence for hypotheses 

 designed to reconcile the "apparent" differences in bacterial and green 

 plant photosynthesis. With increasing awareness of comparative bio- 

 chemical correlations, it became natural to suppose that the light- 



TABLE 1 



Distinctive features of autotrophic )uetaboUs))i in photosynthetic 

 bacteria and green plants 



Photosynthetic 

 bacteria 



Green plants 



Requirement for an "accessory" 

 hydrogen (electron) donor 



Production of oxygen 



dependent metabolism in all photosynthetic organisms must be "basi- 

 cally similar," Thus, the discordant properties of the bacteria as com- 

 pared with higher plants could be viewed as the result of relatively 

 minor variations on a basic theme (1,2). 



Since the time of Pasteur, the power of comparative biochemistry 

 in rationalizing common principles in the framework of metabolism 

 has been amply demonstrated. It is undoubtedly safe to say that at 

 present the comparative biochemical approach is so ingrained that it 

 has become a stock-in-trade aspect of our expanding methodology for 



1 Research of the author is supported by grants from the National Science 

 Foundation (G-9877) and the U. S. Public Health Service (E-2640). 



129 



