Secondary metabolites
Japanese: 二次代謝産物
Compounds not directly necessary for microbial growth but advantageous for survival strategies. Including antibiotics, pigments, toxins, and aromatic compounds, they are deeply involved in fermented food flavors.
Secondary metabolites are compounds not directly necessary for a microorganism's basic life processes (primary metabolism). Yet they are far from unnecessary. Antibiotics, pigments, toxins, aromatic compounds—secondary metabolites are important weapons in microbial survival strategies.
Penicillin from Penicillium, streptomycin from actinomycetes—these are chemical weapons for eliminating competitors, and simultaneously substances that revolutionized human medicine.
In fermented foods, kojic acid (a skin-whitening agent) produced by koji mold and monacolin K from red koji mold are secondary metabolites. Tools for microbial survival; blessings for humans.
Much about the full picture of secondary metabolites remains unknown. In the hidden face of microorganisms, undiscovered treasures may still lie dormant.