Index >> Fundamentals of Microbial Ecology >>Common Terms Used in Microbial Ecology

Habitat It is the place or locality that a given organism normally occupies (e.g. sediments in lakes, humus rich soils, nasal cavity, intestinal tract of humans, etc.). Most of the microbes have just one habitat within an ecosystem with exceptions (e.g. rhizobia grow in soil and in the root hairs of leguminous plants).

Microhabitat When the habitat of a species is highly specialised, as seen in certain species of insects (leaf miners) where they live only in the upper photosynthetic layer of the leaves of certain species of plants. Thus the leaf contributes a microhabitat for leaf miners.

Autochthonous Those that are indigenous and always present in the given ecosystem (soil, intestine, etc.), and their presence is based on the more or less constant supply of nutrients that are typical for the ecosystem. Their numbers are always constant in any ecosystem.

Zymogenous Those that are dependent on an occasional increase in concentration of certain nutrients or on the specific presence of certain nutrients. Their numbers in any ecosystem show an increase only when a particular substrate is present in the ecosystem. For example, there is a rise in the numbers of cellulolytic organisms in the soil only when there is a rise in cellulose  substrate in the soil.