342 Marine Microbiology 



transferred to artificial conditions of the Warburg apparatus for 

 manometric determinations. Whereas from the physiological 

 viewpoint the true regularities in the development of the organ- 

 ism may be observed only under conditions which meet the re- 

 quirements for the natural development of the organism. 



In this connection, it is appropriate to mention the works of 

 Maximova (4, 5, 6) who was the first to investigate the effect 

 of varied intensity of light on the nonsulfur purple bacteria 

 Rhodopseudomonas palustris in normal environmental conditions 

 exposed to light and utilizing ready-made organic compounds. 

 It was found that the light energy requirements of Rh. palustris 

 under conditions photoheterotrophic nutrition are rather low; 

 comparatively low intensities cause light inhibition of the culture. 



It was of great interest for us to investigate the influence of 

 light intensity upon the development of typical photosynthetic 

 purple sulfur bacteria developing at the expense of photoassimila- 

 tion of carbonic acid, and to establish their requirements for light 

 energy. 



The enrichment culture of the photosynthetic purple sulfur 

 bacteria was obtained from silt samples from Lake Beloye. Fol- 

 lowing special cleaning treatment we isolated a pure culture of 

 bacteria which was identified as Chromatiiim vinosum repre- 

 sentative of the Thiorhodaceae, according to morphological and 

 physiological properties (8). 



To provide the optimum environment for the de\ elopment 

 of the culture under laboratory conditions, we chose the following 

 method of cultivation. A sterile medium of composition K2HPO4- 

 0.5%, MgCL - 0.02%, NH.CI - 0.1%, NaCl - 0.5%, Na,S-9H,0 - 0.02%, 

 NaHCO,i-0.5% per liter of distilled water of pH 7.4-7.5 was inoc- 

 ulated with bacteria and poured into sterile, hermetically sealed 

 glass bottles or bottles with ground stoppers. The culture was 

 grown in a thermostat at 27-29° C which was exposed to in- 

 candescent light. 



Under such conditions the culture developed efficiently and 

 a day later a visible growth was noted; in two to three days we ob- 

 served profuse accumulation of the bacterial mass with a purple- 

 red color. The bacteria did not grow in darkness, though they re- 



