Streptomycetes are Gram-positive soil bacteria with a well differentia
ted morphology. They are considered interesting candidates for the pro
duction of heterologous proteins for several reasons, including their
efficient secretion mechanism by which the secreted proteins are local
ized into the culture supernatant. In view of this potential, this rev
iew article describes different aspects of gene expression and regulat
ion in Streptomyces, and summarizes and discusses results obtained usi
ng Streptomyces lividans as host for secretion of heterologus proteins
of prokaryotic and eukaryotic origin.