2.4. Nutrient requirements
All microorganisms need for their microbial activity the presence of several nutrients.
Carbohydrates are capable of being used by all microorganisms, although in no case is there an absolute requirement for this group of organic compounds. Glucose is the most readily metabolized sugar. Most fungi can use disaccharides.
Microbial requirements for steroids, and long-chain fatty acids can be summarized as follows. Long-chain fatty acids like linoleic acid and oleic acid are required for bacteria and fungi. Generally, steroids, other than cholesterol, are not required or utilized by microorganisms. In all fungi, and including yeast, ergosterol is a nutritional requirement.
Purines and pyrimidines
It is generally only in bacteria that cases of purine and pyrimidine metabolism have been reported. Algae do not utilize these compounds at all.
Vitamins and growth factors
There is considerable species variation in the requirements of vitamins and related factors by other microorganisms. Generally, vitamins A, C