Effect of light intensity of vesicle formation in chlorobium.

1. Chlorobium limicola forma sp. thiosulfatophilum was cultivated at 22 and 22000 lux. 2. The content of bchl d on a protein basis in the low light intensity cultures was about twice that of the high light intensity cultures; 3. After growth at 22 lux the red bchl d peak was at c. 743 nm, while at the higher intensity this peak was at c. 732 nm; 4. Electron microscopy of thin sections of Chlorobium revealed that vesicle size was greater at the low light intensity than at the high. 5. This was confirmed by sucrose density gradient centrifugation of differentially 14C-labelled vesicles from cultures grown at the two intensities. 6. The optimum temperature for growth was about 35 degrees C. Incubation at the optimum temperature was particularly beneficial at high light intensity.