Biotransformation - When an organic compound is modified by simple chemically defined reactions, catalyzed by enzymes present in cells, into a product that is recoverable, it is called biotransformation. Both the substrate and the product are not involved in the primary or secondary metabolism of the organism employed.

This is in contrast to the various metabolites, e.g., organic acids, amino acids, antibiotics etc., produced by the complex pathways of primary or secondary metabolism of the organism. Biotransformations are far more efficient and economical due to the rapid microbial growth and high metabolic rates of microorganisms.