However, the step in E. coli host seems inevitable since the classical way to transform Streptomyces whatever the recombinant vector used (integrative or replicative) is a two-step procedure with cloning in E. coli and further intergeneric conjugation between E. coli and Streptomyces (Kieser et al., 2001). The other solutions are (i) a tight control of transcription and/or translation (for example the use of unleaky promoters) and (ii) the manipulation of the cloning vector copy number (See Saida et al., 2006, for a review).