Microbial Nutrition and Growth
All chemicals required by microorganisms (and all other organisms) as raw material for their metabolism and reproduction are called nutrients, and an such events that help fulfilling the requirements of nutrients to and into the body of microorganisms (and all other organisms) are referred to as nutrition. Since a living body consists partly of inorganic and partly of organic chemicals and since all life functions are directed towards maintaining and perpetuating the body, it is clear that an organism must supply itself with both inorganic and organic metabolites; we may recall that organic metabolites are also called food.

The global environment consists of three main sub-divisions. The hydrosphere includes all liquid components i.e. the water in oceans, lakes, rivers and on land; the lithosphere comprises the solid component i.e. the rocky substance of the continents and the atmosphere which is the gaseous mantle that envelops the hydrosphere and lithosphere. Living organisms in general require inorganic metabolites from each of the these subdivisions. The hydrosphere supplies liquid water; the lithosphere supplies all other minerals and carbon dioxide. Together these inorganic materials provide all the chemical elements needed in the construction and maintenance of the living matter.
We shall examine in brief the nutritional aspects of organisms under the following broad heads; nutritional requirements and forms of nutrition