ABSTRACT
Microbes are extremely versatile and can show considerable morphological and/or physiological variation. They are to be found in almost every ecological niche, even seemingly hostile situations, where it would be reasonable to assume that no organism could have the capacity to survive, let alone grow and reproduce. Large numbers of microbial species have been defined, each with its own particular characteristics and requirements. Most micro-organisms can only be seen properly with the aid of a microscope. Micro-organisms are also often divided on the basis of whether they are prokaryotes or eukaryotes. Microbes are sometimes grouped together according to different nutritional modes, although these groups are not mutually exclusive. Placing microbes from a natural environment into culture may immediately tend to favor one particular microbe from a sample.
