The Evolution of Chemosynthesis 633 



chemosynthetic organisms derive energy for CO2 assimilation and reductants 

 from the oxidation of mineral substances. The photosynthetic organisms obtain 

 energy and reductants through photochemical decomposition of water or of 

 certain mineral and organic compounds. The heterotrophic bacteria are not 

 capable of thriving at the expense of the types of metabolism just mentioned. 



The delimitation of each of these physiological groups of micro-organisms is 

 also determined by the place they hold in the economics of Nature. The role of 

 chemoautotrophic bacteria, in particular, consists in that they effect complete 

 oxidation of the mineral products of anaerobic decomposition of organic com- 

 pounds and, by utihzation of the energy contained in these products, involve 

 additional amounts of CO2 in the process of synthesis of organic matter. Thus, 

 chemosynthesis is not a parallel, but a subsequent process in relation to photo- 

 synthesis since in the final analysis the energy for chemosynthesis is derived from 

 products of anaerobic decomposition of organic compounds built up in the 

 process of photosynthesis. 



Chemosynthesis plays an important part in the synthesis of organic matter in 

 water basins, where it is connected with the anaerobic decomposition of organic 

 matter in silt deposits [42, 44]. 



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