Microbes live in all parts of the biosphere. Microbial activities are important in maintaining the stability of the ecosystem. The habitat of a microorganism is governed by the conditions, both physical and chemical, of its location. A habitat can sustain more than one type of microbe due to numerous microenvironments in it!

For every organism there is one niche, called the realized niche, where it is most successful ecologically. Organisms can occupy more than it realized niche but will not be as successful. an important factor in microbial microenvironments is diffusion. If certain nutrients, like oxygen, cannot diffuse into a microbial environment, the deeper layers will contain anaerobic microbes while the outer layers will contain aerobic microbes, making the environment suitable for many types of microorganisms.

Growth rates of microbes are dependant of available nutrients in the environment. Resources are not always available in the environment causing microorganisms in a community to live a “feast-or-famine” existence. This creates competition in a habitat. survival is dependent upon the rate of nutrient uptake, metabolic rate, and growth rate. Some microorganisms can work together to carry out transformation neither can do on its own, called syntrophy.