Abstract:Abstract:[Objective] The mutated promoter of the erythromycin resistance gene(PermE*) is a strong promoter generally used in streptomycetes, and we evaluated the expression activities of a new promoter(Psf) and PermE* in Streptomycetes. [Methods] We used kanamycin resistance gene(neo) and catechol 2,3-dioxygenase gene(xylE) as reporters. [Results] Both promoters exhibited high level of promoter activities in Streptomyces clavuligerus NRRL3585, Streptomyces coelicolor M145, Streptomyces venezuelae ISP5230 and Streptomyces lividans TK54. The activities of Psf were higher than those of PermE* in S. clavuligerus and S. coelicolor. [Conclusion] Both Psf and PermE* are strong promoters suitable for gene over-expression in Streptomycetes and Psf will offer an alternative for high-level gene expression.