Microbial ecology comes of age

Microbial ecology is a scientific field that developed during the second half of the twentieth century. As a cohesive branch of the microbiological sciences, it blossomed in the 1960s during an era of public concern with environmental issues [1]. The publication, in 1962, of Silent Spring by Rachel Carson brought about changes in the perception of nature. The concepts which microbial ecology represents, however, were not new; they were already evident in the pioneering microbiological research of Beijerinck, Winogradsky and others in the late nineteenth century. As a scientific discipline with its own identity, microbial ecology arose from the integration of microbiology and ecology. The principles of general ecology, so brilliantly developed throughout the twentieth century, were based mainly on studies of animals and plants. Ecological studies, however, rarely considered the role of microorganisms in ecosystems, or whether ecological theory could also be applied to those tiny creatures. Nevertheless, only when the principles of ecology can be applied to all living things will they gain universal validity. Overlooking microorganisms in ecological studies means disregarding ‘‘the unseen majority’’ [7], as microorganisms make up most of the biomass on Earth. Furthermore, since they were the only inhabitants of the planet for more than three quarters of life’s history, microorganisms play unique roles in ecosystems. The inclusion of prokaryotes in global ecological studies would almost double estimates of carbon stored in living organisms, not to mention those of nitrogen and phosphorous. In fact, prokaryotes comprise the largest pool of those elements in the biota [7]. The first textbook with the words ‘‘microbial ecology’’ in the title, authored by Thomas D. Brock, was published in 1966 [3]. It was followed by Sheldon Aaronson’s Experimental Microbial Ecology, in 1970, and Martin Alexander’s Microbial Ecology, in 1971. Since then, many other scientists have contributed – either directly or indirectly – to the development of the subject to its current status. The journal Microbial Ecology (Springer Verlag) has been published since 1974. (See comprehensive lists of books and periodicals on microbial ecology in [1].) The relatively newness of microbial ecology accounts for the lack of definition of its tremendous complexity and for the multiple approaches necessary for its development. Microbial ecology deals with natural processes, with interactions between microorganisms, and between microorganisms and other species and the environment. It also offers new clues to solve problems that modern human societies face. The breadth of subjects that make up microbial ecology include autoecology, or ecology of genetically related populations; ecology of specific ecosystems such as lakes or the rumen; biogeochemical ecology, which studies biogeochemical cycles; ecology of relationships between associated microand ‘‘macroorganisms’’; and applied microbial ecology [4].