STREPTOFACTIN, A NOVEL BIOSURFACTANT WITH AERIAL MYCELIUM INDUCING ACTIVITY FROM STREPTOMYCES-TENDAE TU 901 8C/

Streptomyces tendae Tu 901/8c produces an extracellular hydrophobic pe ptide, termed streptofactin. The compound was isolated from conditione d agar medium and characterized. Streptofactin is a mixture of structu rally related peptides with the major components ranging in size from 1003 m/z to 1127 m/z. Extracellular application of the purified peptid e restored the capacity to form aerial mycelium in mutants defective i n morphological development. Surface activity measurements revealed th at streptofactin decreased the surface tension of water from 72.0 mN m (-1) to 39.4 mN m(-1) and achieved a critical micelle concentration va lue of 36 mg l(-1). The properties of streptofactin suggest that it pl ays a structural role in aerial mycelium development and supports the erection of aerial hyphae by lowering the surface tension of water fil ms enclosing the colonies. A model for aerial mycelium formation which represents a novel mechanism for the adaption to environmental change s in Streptomyces is proposed. (C) 1998 Federation of European Microbi ological Societies. Published by Elsevier Science B.V. All rights rese rved.