海洋与内陆盐环境嗜盐古菌比较分类学研究

The current standards for description of new taxa in the order Halobacteriales is not suitable for the development of taxonomy of halophilic archaea. The new taxonomic standards should be proposed based on the identification of diverse halophilic archaeal strains from diverse hypersaline environments. In addition to more than 100 artificial marine solar salterns in offshore areas along the coast of marginal sea at Eastern and Southern China, more than 1000 inland salt lakes, salt mines and artificial salt wells are distributed throughout the mid and west regions of China. These diverse hypersaline environments with diverse origin harbour diverse halophilic archaea which can be used to propose the new taxonomic standards for description of taxa. To construct the new taxonomic standards for description of halophilic archaea from diverse hypersaline environments, Illumina sequencing based on environmental DNA and cultivation using low molecular weight organic acid salt as carbon source will be employed to survey and to compare the haloarchaeal diversity in these representative hypersaline environments. The halophilic archaeal population and community of these environments will be determined and compared to differentiate the diverse biological characteristics of these halophilic archaea. The environment factor, climate impact and ecological driving force on biodiversity of the hypersaline environments will also be illuminated to understand the biogeographic pattens of halophilic archaea. Chemical taxonomic methods based on the modern mass spectrometry and systemetic taxonomic methods will also be choosed to illuminate the polar lipids composition and the phylogeny of diverse halophilic archaea. The current standards for description of new taxa in the order Halobacteriales will be revised according to the acquired data. If the research proposal is approved and brought into effect, the halophilic archaeal diversity and distribution pattern of marine solar salterns and diverse inland hypersaline environments will be elucidated. Furthermore, the achievements of this study will help to construct the perfect taxonomic system for classification of halophilic archaea.

现行嗜盐古菌分类标准已不适应嗜盐古菌分类学的发展，新的分类标准必须建立在针对不同盐环境多样性类群研究的基础上。我国东、南部沿海建设有上百家海水盐场，中西部地区分布着近千个内陆盐湖、盐矿和盐井，这些不同起源的盐环境蕴藏的多样性嗜盐古菌，形成了独特的种群组成与群落结构，是研究和建立嗜盐古菌新分类标准的珍贵资源。在前期研究基础上，本项目拟采用基于环境DNA的宏基因组高通量测序技术和基于小分子有机酸盐的低营养培养技术，研究不同盐环境中嗜盐古菌种群分布与群落构成，比较不同盐环境嗜盐古菌的生物学特性，揭示不同盐环境嗜盐古菌生物地理分布格局；运用基于现代质谱分析技术的化学分类法和基于多基因分析的系统分类法，比较嗜盐古菌不同种属水平的极性脂组成，推断嗜盐古菌系统演化关系，修订嗜盐古菌分类标准。项目的立项和实施，不仅能阐明我国海洋与内陆盐环境嗜盐古菌的分布格局，而且能构建完善的嗜盐古菌分类学体系。

嗜盐古菌（Halophilic archaea）属于古菌域（Archaea）、广古菌门（Euryarchaeota）、嗜盐菌纲（Halobacteria）。现行的嗜盐古菌分类标准已不能适应嗜盐古菌分类学的发展，分类标准的修订必须建立在针对不同盐环境多样性类群研究的基础之上。我国东、南部沿海建设有上百家海水盐场，中西部地区分布着近千个内陆盐湖、盐矿和盐井，这些不同起源的盐环境蕴藏的多样性嗜盐古菌，形成了独特的种群组成与群落结构，是研究和建立嗜盐古菌新分类标准的珍贵资源。为了建立嗜盐古菌新分类标准，采用基于环境DNA的宏基因组高通量测序技术和基于小分子有机酸盐的低营养培养技术，研究不同盐环境中嗜盐古菌种群分布与群落构成，比较不同盐环境嗜盐古菌的生物学特性，揭示不同盐环境嗜盐古菌分布格局；运用化学分类法和系统分类法，比较嗜盐古菌不同种属水平的极性脂组成，推断嗜盐古菌系统演化关系，修订嗜盐古菌分类标准。研究结果表明：.（1）不同盐环境中的嗜盐古菌多样性存在差异，其优势类群也不尽相同，Halorubrum类群是海盐田中最多的有优势类群，Haloterrigena类群是盐湖中最多的有优势类群，海洋和内陆盐环境中均存在着大量的尚不能培养的嗜盐古菌类群。.（2）菌红素不能作为嗜盐古菌的分类和鉴定中的鉴别性指标，而极性脂可以作为不同分类单元描述中的重要指标。.（3）基于16S rRNA基因、rpoB'基因、atpA基因和EF-2基因的嗜盐古菌部分属级系统发育格局存在差异。.在上述研究基础上，我们修订并提出“嗜盐古菌分类单元的描述标准”。