GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

21. MICROORGANISMS AND THE ENVIRONMENT

21.2. MICROBIAL ECOLOGY (BASIC CONCEPTS)

Ecology is the science that studies the relationships among organisms and their interactions with the environment. Microbial Ecology focuses on specific components of integral ecological systems. The fundamental unit of ecology is the ecosystem, which comprises both biotic and abiotic components. The biotic components form a community of organisms, or biocenosis, which typically refers to microbial populations consisting of one or more species. The abiotic components represent the physicochemical conditions of the ecosystem where the organisms live. Examples of ecosystems include a lake, a plant ROOT system, the rumen of a ruminant, the human Oral Cavity, and others. The entire living space of our planet — the biosphere — can be viewed as a giant ecosystem. The term "environment" is frequently associated with a particular ecosystem; it maintains The connection between a specific Organism (or population) and the surrounding biotic and abiotic Components of the ecosystem.

Within an ecosystem, a habitat can be defined for each species. A habitat is the specific area or living space occupied by a given organism (individual or population). In contrast to the term "habitat," METABOLISM/2.html">THE CONCEPT OF an "ecological niche" reflects not a spatial Location, but rather the functional role of a particular species or population within the community of organisms.

All microorganisms in an ecosystem can be divided into two categories: autochthonous and allochthonous. Autochthonous microorganisms are native inhabitants of a given ecosystem and are permanently present in it. The presence of allochthonous (zymogenic) microorganisms depends on a transient increase in nutrient concentration or the Introduction of specific compounds.