Microorganisms require nutrients that are essential for energy production as well as their growth and multiplication. These nutritional requirements can be broadly categorized into macronutrients, micronutrients, and growth factors.

Macronutrients are required in relatively large amounts and include carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, potassium, calcium, magnesium, and iron. Among these, C, O, H, N, S, and P are the components of carbohydrates, lipids, proteins and nucleic acids. K, Ca, Mg, and Fe play a variety of roles, being involved as cofactors of various enzymes.

Micronutrients or trace elements such as Mn, Zn, Co, Mo, Ni, and Cu are required in small amounts for microbial growth. These micronutrients are ubiquitous in nature and already exist with various regular media components, so they are not usually supplied separately.

Carbon source is required for the skeleton or backbone of all organic molecules. Carbon sources usually also provide oxygen and hydrogen atoms. Examples include glucose, lactose, sucrose, starch, glycogen, cellulose, cereal grain powders, and cane molasses.

Nitrogen, phosphorus and sulphur sources are essential for biosynthesis. Nitrogen is required for amino acids, nucleic acids and enzymes, with sources like ammonium salts, urea, and tissue extracts. Phosphorus is present in nucleic acids and phospholipids, sourced from inorganic phosphate. Sulphur is needed for amino acids like cysteine and methionine, obtained from sulfate. Growth factors are organic compounds like amino acids, purines, pyrimidines, and vitamins that cannot be synthesised in cells.