Autoradiography as a Tool in Microbial Ecology

Abstract

THE importance of micro-organisms as agents of biochemical transformations in natural environments is well established. But micro-organisms are small and thus their environments are also small, so that micro-organisms can be investigated directly in Nature only by the use of the microscope. Although the microscope can be used to see where various organisms are situated in a micro-environment and how organisms are disposed with relation to one another, one cannot, however, study microscopically many of the characteristics of an organism which are of greatest ecological interest: that is to say, nutritional requirements, responses to environmental changes, production of metabolites and growth rate. The usual approach for the study of these latter phenomena has been to isolate micro-organisms in pure culture and attempt to infer from the behaviour of the pure culture the behaviour of the parent organism in Nature. However, it is clear that the behaviour of the pure culture reveals the potentiality of the organism in Nature, but does not show what the organism was actually doing, since the organism has undoubtedly adapted to the cultural conditions used. Further, even if the laboratory conditions precisely mimic the natural conditions, the laboratory environment cannot reproduce the natural environment, since the natural environment contains the additional elements of competition and co-operation with other organisms.