地衣型真菌石果衣(疣孢菌科,子囊菌门)次级代谢产物的多样性

Diversity of secondary metabolites from the lichen-forming fungus Endocarpon pusillum(Verrucariaceae,Ascomycota)

地衣能够产生大量的新型次级代谢产物,但以往对石果衣Endocarpon pusillum的研究中未能检测出任何次级代谢产物。然而,对其共生菌进行基因组测序发现其中含有14个沉默的PKS基因和2个沉默的NRPS基因。在此研究中,为激活其途径,使用了优化马铃薯培养基和大米培养基对石果衣共生真菌进行了培养。从优化马铃薯培养物中分离得到9个次级代谢产物,包括2个新的异吲哚-1-酮类化合物(1,2)。而从大米培养物中分离到3个已知化合物和1个新的萘醌类化合物(9)。通过核磁共振和质谱数据确定了新化合物的结构。研究结果表明,大量地衣中未能检测出任何次级代谢产物,或仅能检测出少量次级代谢产物,可能与其基因组中的沉默基因有关。因此,通过对沉默基因的激活方法为地衣次级代谢产物资源的研究与开发开辟了有效途径。

Lichens could produce a vast number of novel secondary metabolites but previous studies on Endocarpon pusillum affirmed that no secondary metabolite could be detected.However,genome sequencing of the lichen revealed 14 silent PKS genes and 2 NRPS genes.To activate the genes E.pusillum was cultured in optimized potato dextrose broth(PDB)and rice medium.Nine secondary metabolites including two new isoindolin-1-ones(1 and 2)were detected from the optimized PDB culture of the mycobiont,while three known compounds and a new naphthoquinone(9)were isolated from the rice culture.Structures of the new compounds were determined by NMR and MS data.The findings suggest that none or few detection of secondary metabolites in large number of lichens is probably related to the silenced genes in their genomes.Therefore,the activation method of silenced genes opens up an effective way for the research and development of lichen secondary metabolite resources.