Pyrosequencing analysis revealed complex endogenetic microorganism community from natural DongChong XiaCao and its microhabitat

Abstract

Background: Ophiocordyceps sinensis (DongChong XiaCao (DCXC) in Chinese), a fungal parasite of caterpillars, is a traditional Chinese medicine. Bioactive components isolated from natural DCXC possess a wide range of pharmacological actions. Many efforts have been directed towards isolating the fungi based on culture-dependent methods for investigation of fungal diversity in order to determine the anamorph of natural DCXC and find new medicinal fungi resources, and the results have been varied. Results: In the present study, a total of 44,588 bacterial and 51,584 fungal sequences corresponding to 11,694 and 9297 putative operational taxonomic units (OTU) were respectively identified by a Roche/454-based, high throughput sequence analysis of 16S rRNA genes and ITS regions. The main bacterial groups were Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria and Firmicutes, while the Ascomycota, Basidiomycota and Zygomycota were the main fungal phyla. Proteobacteria presented 68.4, 49.5, 38.9 and 35.6 % of all bacteria in the sclerotia, stromata, external mycelial cortices and soil, respectively. As the main fungi phyla, Ascomycota presented 21.0, 45.6 26.4 and 59.3 % in the sclerotia, stromata, external mycelial cortices and soil, respectively. Bacterial and fungal communities were more diverse in the environmental sample than in the natural DCXC sample. Microbial communities were obviously distinct in each sample. Several novel unclassifiable bacterial (10.41 %) and fungal (37.92 %) species were also detected. Conclusions: This study revealed an abundant endogenetic fungal and bacterial resources and a variety of genetic information in natural DCXC by high-throughput 454 sequencing technology. Microorganism that had been discovered in natural DCXC will provide sources for screening the new bioactive metabolites and its biotechnological application.