The fermentation products of Streptomyces sp. GEMSM 4(6) have a distinct activity against Gram-positive and Gram-negative bacteria,yeast and filamentous fungi,especially phytopathogens.Three noribosomal peptide synthetase (NRPS) genes and fifteen polyketide synthase (PKS) genes were amplified from the genome of this streptomycete with PCR using degenerated primers.Bioinformatics analysis revealed that the PKS genes had highest homology (91%-99% identity) with that in Streptomyces violaceusniger Tu 4113,while the NRPS genes only had homology of 60%-62% with known NRPS genes in database.To clone these novel NRPS biosynthetic gene clusters,a genomic bacterial artificial chromosome (BAC) library was constructed and screened by PCR.It will provide a good foundation for heterologous expression and genome mining in the future.