ABSTRACT
All microorganisms require a source of nutrient to enable them to grow. Simple sugars such as glucose and sucrose, proteins, lipids and polysaccharides all make excellent carbon sources for heterotrophic microorganisms. Although some organisms can "fix" atmospheric nitrogen, and many can utilize simple nitrates and ammonium salts, the amino acids and proteins in foods make excellent nitrogen sources for the growth of most microorganisms. Most microorganisms can use inorganic phosphates as their source of this nutrient. Many microorganisms can utilize inorganic sulfate, but others require the sulfur-containing amino acids as a source of this nutrient. Vitamins can often be synthesized by many microorganisms, but others, known as fastidious organisms, need to be supplied with one or more of them. One of the major requirements of a microbiology laboratory is for a medium on which most microorganisms of interest will grow.
