永兴岛白穗软珊瑚共附生放线菌筛选及部分活性次级代谢产物的鉴定

Isolation of Actinobacteria with antibiotic activity associated with Soft Coral Nephthea sp．

摘要:

摘要:【目的】从白穗软珊瑚中分离和鉴定共附生放线菌，运用PCR 技术对所分离的放线菌进行I 型聚酮合酶(PKS)筛选，研究其次级代谢产物。【方法】使用11 种培养基对白穗软珊瑚共附生放线菌进行分离、鉴定，构建16S rRNA基因系统发育进化树，以基于I 型PKS的KS基因设计的简并引物对所分离放线菌进行基因筛选，对阳性菌株用3种培养基发酵检测，对目标菌株进行放大规模发酵分离鉴定次级代谢产物。【结果】从白穗软珊瑚中分离到20株共附生放线菌，包括链霉菌属10株、迪茨氏菌属2株和盐水孢菌属8株，筛选获得18株I型PKS阳性菌株，并从菌株Salinospora arenicola SH04中分离到化合物rifamycin S和rifamycinW。【结论】首次从珊瑚共附生环境中分离得到海洋专属性稀有放线菌盐水孢菌属，并以I 型PKS基因筛选为指导，分离鉴定了聚酮类化合物rifamycins，为研究软珊瑚共附生可培养放线菌的多样性和基于基因筛选指导分离次级代谢产物提供了可靠依据。

Abstract:

Abstract:［Objective］The present study aims to isolate and identify actinobacteria associated with the soft coral Nephthea sp.,and to isolate natural products from these actinobacteria under the guidance of PCR screening for polyketides synthase (PKS) genes.［Methods］Eleven selective media were used to isolate actinobacteria associated with the soft coral Nephthea sp. collected from Yongxin Island． The isolated actinobacteria were classified on the basis of phylogenetic tree analysis of their 16S rRNA genes. Degenerated primers targeted on conserved KS (ketoacyl-synthase) domain of type I PKS genes were used to screen for potential isolates. The positive isolates were cultured in three different media to check their producing profiles. One bioactive strain that is rich in metabolites was subjected to larger scale fermentation for isolating bioactive natural products.［Results］A total of 20 strains were isolated from Nephthea sp., and were categorized into 3 genera including Streptomyces，Dietzia and Salinospora，among which18 strains were positive in screening with type I PKS genes. Two bioactive compounds rifamycin S and rifamycin W were isolated and identified from Salinospora arenicola SH04． ［Conclusion］This is the first report of isolating indigenous marine actinobacteria Salinospora from the soft coral Nephthea sp. It provides an example of isolating bioactive secondary metabolites from cultivable actinobacteria associated with Nephthea sp. by PCR screening.