The Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education and Laboratory for Conservation and Utilization of Bio-Resources, Yunnan Institute of Microbiology, Yunnan University, Kunming 650091, Yunnan, China.
Environ Microbiol Rep. 2012 Oct;4(5):522-31. doi: 10.1111/j.1758-2229.2012.00357.x. Epub 2012 May 24.
Endophytes are now considered as an important component of biodiversity. However, the diversity of endophytic actinobacteria associated with tropical rainforest native medicinal plants is essentially unknown. In this study, the diversity of endophytic actinobacteria residing in root, stem and leaf tissues of medicinal plant Maytenus austroyunnanensis collected from tropical rainforest in Xishuangbanna, China was investigated with a combination of cultivation and culture-independent analysis on the basis of 16S rRNA gene sequencing. By using different selective isolation media and methods, a total of 312 actinobacteria were obtained, and they were affiliated with the order Actinomycetales (distributed into 21 genera). Based on a protocol for endophytes enrichment, three 16S rRNA gene clone libraries were constructed and 84 distinct operational taxonomic units were identified and they distributed among the orders Actinomycetales and Acidimicrobiales, including eight suborders and at least 38 genera with a number of rare actinobacteria genera. Phylogenetic analysis showed that 32% of the clones in the libraries had lower than 97% similarities with related type strains. Interestingly, six genera from the order Actinomycetales and uncultured clones from Acidimicrobiales have not, to our knowledge, been previously reported as endophytes. Our study confirms abundant endophytic actinobacterial consortium in tropical rainforest native plant and suggests that this special habitat represents an underexplored reservoir of diverse and novel actinobacteria of potential interest for bioactive compounds discovery.
内生菌现在被认为是生物多样性的一个重要组成部分。然而，与热带雨林本土药用植物相关的内生放线菌的多样性基本上是未知的。在这项研究中，我们结合培养和基于 16S rRNA 基因测序的非培养分析，调查了来自中国西双版纳热带雨林的药用植物五月茶 Maytenus austroyunnanensis 的根、茎和叶组织中内生放线菌的多样性。通过使用不同的选择性分离培养基和方法，共获得了 312 株放线菌，它们隶属于放线菌目（分布在 21 个属中）。基于内生菌富集方案，构建了三个 16S rRNA 基因克隆文库，鉴定出 84 个独特的操作分类单元，它们分布在放线菌目和酸微菌目，包括 8 个亚目和至少 38 个属，其中有许多稀有放线菌属。系统发育分析表明，文库中 32%的克隆与相关模式菌株的相似度低于 97%。有趣的是，从放线菌目分离的 6 个属和酸微菌目中的未培养克隆，据我们所知，以前没有被报道为内生菌。我们的研究证实了热带雨林本土植物中丰富的内生放线菌群落，并表明这种特殊的栖息地代表了一个尚未充分探索的多样化和新型放线菌的潜在宝库，具有发现生物活性化合物的潜力。
