Microbial toxins, their functional role and phylogenetic validity.

Microbially produced toxins, which appear to lack a role in microbial survival, may be antimicrobial compounds of significance to the producers. These toxin/antibiotics may act against cell metabolism shared by man or animals and other microorganisms. Protein toxin/antibiotics are produced by single species of bacteria. Those from fungi and algae are nonprotein secondary metabolites and several microorganisms may make the same or similar toxin/antibiotics.