344 Marine Microbiology 



TABLE 2 



The Consumption by Chr. vinosum of Organic Acids as 

 THE Sole Carbon Source in the Medium 



course of eight to twelve days; it should be noted that the bulk 

 of the carbon consumed from the acetic acid was used for build- 

 ing the material of the bacterial cells, as seen from the corre- 

 sponding increase of the cell carbon content. The culture was 

 able to incorporate the propionic acid by constructive metabolism; 

 the consumption of the propionic acid in the course of ten to 

 twelve days amounted to 4.5-6 m moles. Judging by the consider- 

 able increase of the bacterial cell carbon for the same period of 

 time, one may assume that the carbon of the propionic acid is 

 in the main involved in the building up of bacterial cells. 



In the development of Chr. vinosum in a medium containing 

 acetic and propionic acids ( both of them are regarded as sources 

 of carbon for the bacteria), the acetic acid is consumed more 

 intensely than propionic. 



The data presented enables us to conclude that the purple 

 sulfur bacteria Chr. vinosum, though an autotrophic organism by 

 nature, is capable of switching over to photoheterotrophic nutri- 

 tion (entirely or partially) under certain environmental condi- 

 tions; the change of nutrients does not impair its development. 

 The task of our further study was to investigate the influence 

 of the intensity of light upon photoautotrophic development. 



The experiments on the effect of varied light intensities were 



