title: The natural functions of secondary metabolites.
abstract: Secondary metabolites, including antibiotics, are produced in nature and serve survival functions for the organisms producing them. The antibiotics are a heterogeneous group, the functions of some being related to and others being unrelated to their antimicrobial activities. Secondary metabolites serve: (i) as competitive weapons used against other bacteria, fungi, amoebae, plants, insects, and large animals; (ii) as metal transporting agents; (iii) as agents of symbiosis between microbes and plants, nematodes, insects, and higher animals; (iv) as sexual hormones; and (v) as differentiation effectors. Although antibiotics are not obligatory for sporulation, some secondary metabolites (including antibiotics) stimulate spore formation and inhibit or stimulate germination. Formation of secondary metabolites and spores are regulated by similar factors. This similarity could insure secondary metabolite production during sporulation. Thus the secondary metabolite can: (i) slow down germination of spores until a less competitive environment and more favorable conditions for growth exist; (ii) protect the dormant or initiated spore from consumption by amoebae; or (iii) cleanse the immediate environment of competing microorganisms during germination.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA. demain@mit.edu
authors.forename: A L
authors.initials: AL
authors.lastname: Demain
authors.forename: A
authors.initials: A
authors.lastname: Fang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000266:history / Q000494:pharmacology; D000898:Antibiosis; D001685:Biological Factors / Q000266:history / Q000502:physiology*; D002454:Cell Differentiation; D012739:Gonadal Steroid Hormones / Q000266:history / Q000502:physiology; D049670:History, 17th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049690:History, Ancient; D049691:History, Medieval; D006801:Humans; D007218:Industrial Microbiology / Q000266:history; D008670:Metals / Q000378:metabolism; D017262:Siderophores; D013170:Spores / Q000378:metabolism; D013559:Symbiosis
chemical_list: D000900:Anti-Bacterial Agents; D001685:Biological Factors; D012739:Gonadal Steroid Hormones; D008670:Metals; D017262:Siderophores