The Evolution of Chemosynthesis 



Yu. I. SOROKIN 

 'Borok' Biological Station, U.S.S.R. Academy of Sciences 



An extensive body of factual material is already available on the morphology, 

 physiology and systematics of chemoautotrophic organisms [i, 2]. But the views 

 on the essence of chemoautotrophy are still controversial, as evidenced by the 

 proceedings of the Fourth Conference on autotrophy in micro-organisms held 

 by the British Society for General Microbiology. We beheve that such a situa- 

 tion results from the absence of a consistent and well supported theory' of the 

 evolution of chemosynthesis. Many investigators — intentionally or otherwise — 

 still attach paramount importance to insufficiently supported conceptions 

 regarding the evolution of chemosynthetic organisms, considering them as the 

 primary forms of Ufe or, at any rate, as organisms with a 'special' primitive meta- 

 bohsm. The absence of any substantiated notions regarding the evolution of 

 chemosynthesis accounts for the fact that some investigators, for example, 

 artificially single out a group of 'anorgo-oxidants', believing them to be the real 

 autotrophs [3]. Other authors generally consider it unnecessary to single out 

 the chemosynthetic organism as a special physiological group of microbes [4-5]. 

 According to Stephenson [2] chemosynthetic micro-organisms have not developed 

 as advantageous methods of utilizing energy as green plants or heterotrophic 

 bacteria. This, in her opinion, is the reason why the autotrophs are so rare in 

 nature and the number of their forms is limited. 



It follows from the above that one conception or another concerning the evo- 

 lution of chemosynthetics will lead to their being considered either as rudi- 

 mentary remnants of a group of primitive primary organisms which have persisted 

 up to the present, or, on the contrary, as a highly perfected group of organisms of 

 wide occurrence in nature. Hence the problem of evolution of chemosynthetics 

 is an indispensable basis for all conceptions dealing with the essence of chemo- 

 synthesis and its importance in natural processes. 



To-day there exist two principal viewpoints concerning the evolution of 

 chemosynthesis. Some authors beheve that chemoautotrophic bacteria could have 

 been the 'pioneers of life', since they are capable of thriving in the absence of 

 ready organic matter. In this case the primitiveness of their nutrient require- 

 ments is related to a primitive type of metabohsm. The opinion that chemo- 

 synthetic microbes might be the first organisms that originated on the Earth 

 was first voiced by Vinogradsky [6]. There is no doubt that it is precisely this 

 idea about the primitive character of metabolism of chemosynthetic organisms 

 that led him to define these organisms as 'anorgo-oxidants' incapable of assimi- 

 lating organic matter [7]. Vinogradsky's views were supported by Osborn [8] in 



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