链霉菌GEMSM4(6)中聚酮合酶和非核糖体多肽合成酶基因的筛选及克隆
Screening and cloning of genes of ployketide synthase and nonribosomal peptide synthetase from Streptomyces sp. GEMSM 4(6)

链霉菌GEMSM 4(6)的发酵产物具有抗革兰氏阳性菌和阴性菌的活性，同时还对酵母及丝状真菌尤其是植物病原菌，具有较强的抑制作用。本研究利用简并性引物对该链霉菌基因组中可能存在的聚酮合酶（PKS）和非核糖体多肽合成酶（NRPS）基因进行PCR扩增及序列分析，找到了3个NRPS及15个PKS基因的片段,其中PKS基因与Streptomyces violaceusniger Tu 4113的PKS基因序列同源性最高，达到91%~99%;而NRPS基因与数据库中已知的NRPS基因序列同源性仅为60%~62%。为克隆NRPS生物合成基因簇，构建了链霉菌GEMSM 4(6)的基因组细菌人工染色体（BAC）文库，通过PCR筛选得到包含有这3个NRPS基因的克隆子，为后期的异源表达及基因组发掘分析提供基础。
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.