THE ROLE OF ORGANIC SUBSTRATES IN PHOTOSYNTHESIS OF PURPLE BACTERIA.

A representative of the photosynthetic non-sulfur purple bacteria (Athiorhodaceae) capable of using simple alcohols has been isolated in pure culture. By means of quantitative analysis of cultures at different stages of development it has been shown that this organism converts isopropanol quantitatively into acetone, simultaneously reducing CO(2) in the light. The data can be represented by the equation 2 CH(3)CHOHCH(3) + CO(2) --> 2 CH(3)COCH(3) + (CH(2)O) + H(2)O. Manometric experiments with suspensions of resting cells have fully corroborated the results obtained with growing cultures. The experiments have conclusively proved that an organic substrate may fulfill exclusively the function of hydrogen donor for the photochemical CO(2)-reduction in purple bacteria photosynthesis.