Streptomyces and Bacillus host cells comprising a recombinant nucleic acid encoding a fusion protein containing a signal sequence and a Streptomyces subtilisin inhibitor (SSI) protein are provided, as well as methods of producing SSI protein using those cells. In certain embodiments, the host cell is a Streptomyces host cell and the signal sequence is a celA signal sequence. In other embodiments, the host cell is a Bacillus host cell has a genome that contains inactivated protease genes.