Diversity Of Endophytic Fungi In The Rhizoma Of Curcuma Lortga And Biotransformation Of Curcumin By Endophytic Fungus Diaporthe Sp.

Endophytic fungi mean a group of fungal microorganisms that inhabit in the livingplant tissues and organs during the whole or part of their life cycle, and cause noapparent symptoms of disease to the host plants. Endophytic fungi are distributedwidely inside the tissues of host plant, and have abundant species diversity. Recentstudies showed that endophytic fungi in the medicinal plants could produce the same orsimilar secondary metabolites as the host did, which play the important roles such asantibacterial, antioxidation, tumor inhibition, diabetes resistance and immunologicalinhibition properties. In addition, they could porduce some novel compounds at theprocess of microbial fermentation. Therefore, endophytic fungi are important microbialresources for screening drug seeds. Curcuma longa is a kind of taditional medicinalherb, but there has no report about some research on endophytic fungi of Curcumalonga. In this paper, we investigated the biodiversity and ecological distribution ofendophytic fungi in the rhizoma of Curcuma longa, and screenedcurcumin-biotansforming endophytic fungus and elucidated the transformed products ofcurcumin. The work will provide some bacial knownledge to understand the symbioticrelationship between endophytic fungi and Curcuma longa, the origin and evolution ofendophytes, and develop some bioactive curcumin derivatives.Endophytic fungi were isolated from the rhizoma of Curcuma longa withsurface-sterilization method in Spring and Winter respectively.51strains of endophyticfungi (33isolates/Spring,18isolates/Winter) were obtained from the tissue segmentsof plant samples, identified by morphological characteristics and the analysis of internaltranscribed spacer (ITS) fragment of rDNA and classified into8genera(Fusarium,Gibberella, Alternaria, Phomopsis, Diaporthe, Nectria, Botryosphaeria, Mucor),belonging to8families(Tuberculariaceae, Dematiaceae, Sphaeropsidaceae,Diaporthaceae, Nectriaceae, Hypocreaceae, Botryosphaeriaceae, Mucoraceae) of7orders(Tuberculariales, Hyphomycetales, Sphaeropsidales, Diaporthales, Hypocreales,Pleosporales, Mucorales) in five classes (Hyphomycetes, Coelomycetes, Pyrenomycetes,Loculoascomycetes, Zygomycetes). Of which, Fusarium(51.0%) and Gibberella(17.6%)were dominant genera in the rhizoma of Curcuma longa. The isolated strains in Springwere classified into7genera (total isolation rate82.5%) and in Winter belonged to4genera (total isolation rate45.0%). The results showed that there were abundant speciesdiversity and genetic diversity of endophytic fungi isolated from the rhizoma ofCurcuma longa, the population composition and distribution of endophytic fungusvaried with seasons to a certain extent, and some endophytes (Fusarium sp.) had apreference to colonize in the rhizoma of Curcuma longa.Screening test for the microbial transformation of curcumin was carried out using thin layer chromatography (TLC) and HPLC. Bio-transformed products of curcuminwere isolated and purified by silica column chromatography and preparative HPLC,and chemical structures of transformed products were elucidated on the basis ofchemical spectral data. Among totally51endophytic fungi, one filamentous fungusCLS23was found to transform curcumin into demethylcurcumin andbisdemethylcurcumin, which was identified preliminarily as Diaporthe sp. bymorphological characteristics and the analysis of ITS1-5.8S-ITS2rDNA region. Theresults indicated that endophytic fungus CLS23(Diaporthe sp.) possessedO-demethylation enzyme system, and was able to modify the chemical structure ofcurcumin by demethylation reaction.