红树林链霉菌ZFSM1-146中抗菌活性物质的发现

Discovery of antibacterial compounds from a mangrove Streptomyces strain ZFSM1-146

摘要:

[背景] 红树林来源的放线菌蕴含着丰富的次级代谢产物资源，是挖掘小分子药物的重要来源。[目的] 对红树林放线菌天然产物进行研究，分离和鉴定其中的抗菌活性化合物。[方法] 采用稀释涂布平板法分离纯化红树林土壤中的放线菌，通过琼脂块法初筛和滤纸片法复筛获得具有抗菌活性的放线菌；基于16S rRNA基因序列分析和系统发育树构建确定目标放线菌种类；通过高效液相色谱法对目标放线菌的发酵产物进行分析，采用硅胶柱层析和高效液相色谱分离技术结合的活性追踪法纯化抗菌活性物质；经高分辨电喷雾电离质谱和核磁共振波谱技术鉴定抗菌活性物质的结构。[结果] 从红树林土壤中筛选到一株抗菌活性较强的放线菌ZFSM1-146，16S rRNA基因序列及其基因片段构建的系统发育树分析初步确定其为抗生链霉菌（Streptomyces antibioticus）；菌株ZFSM1-146可产生抗菌活性化合物1-3，化合物1-3经结构鉴定分别为放线菌素X_Oβ、X₂和D。经培养基初步优化，抗菌活性最强的放线菌素X₂的产量约达到原来的2倍。[结论] 从红树林土壤中筛选出一株可产生抗菌活性物质的抗生链霉菌ZFSM1-146，并鉴定出3个抗菌活性成分均为放线菌素类化合物，为后续进行放线菌素的产量优化和通过分子遗传手段进行结构改造提供了宝贵的菌种资源。

Abstract:

[Background] Secondary metabolites from mangrove actinomycetes are an important source for the discovery of small molecule drugs. [Objective] To isolate and identify the antibacterial secondary metabolites from mangrove actinomycetes. [Methods] The mangrove actinomycete strains were separated and purified using dilution plate method, and antibacterial activity of the strains were assayed by agar block and filter disk methods. The 16S rRNA gene sequence of an actinomycete strain was used for species analysis and construction of the phylogenetic tree. The fermentation broth of the actinomycete strain was analyzed by high performance liquid chromatography (HPLC), and the antibacterial compounds were purified by silica gel column chromatography and HPLC combining with activity-tracking method. The structures of the antibacterial compounds were elucidated by high resolution electrospray ionization mass spectroscopy (HR-ESI-MS) and nuclear magnetic resonance (NMR). [Results] An actinomycetes strain ZFSM1-146 with strong antibacterial activity was obtained from mangrove soil. Species and phylogenetic tree analysis showed that the strain belongs to Streptomyces antibioticus. Strain ZFSM1-146 could produce antibacterial compounds 1-3, which were identified as actinomycin X_Oβ, X₂ and D, respectively. After preliminary medium optimization, the yield of actinomycin X₂, which showed the strongest antibacterial activity among the 3 compounds, was almost twice as the original yield. [Conclusion] S. antibioticus ZFSM1-146 was obtained from mangrove soil and could produce antibacterial compound actinomycins. This study provided a valuable strain for improving the yield of actinomycins as well as producing new analogs through genetic manipulation.