Data from: Structure of the rare archaeal biosphere and seasonal dynamics of active ecotypes in surface coastal waters

Marine Archaea are important players among microbial plankton and significantly contribute to biogeochemical cycles, but details regarding their community structure and long-term seasonal activity and dynamics remain largely unexplored. In this study, we monitored the inter-annual archaeal community composition of abundant and rare biospheres in northwestern Mediterranean Sea surface waters by pyrosequencing 16S rDNA and rRNA. A detailed analysis of the rare biosphere structure showed that the rare archaeal community was composed of three distinct fractions. One contained the rare Archaea that became abundant at different times within the same ecosystem; these cells were typically not dormant, and we hypothesize that they represent a local seed bank that is specific and essential for ecosystem functioning through cycling seasonal environmental conditions. The second fraction contained cells that were uncommon in public databases and not active, consisting of aliens to the studied ecosystem and representing a non-local seed bank of potential colonizers. The third fraction contained Archaea that were always rare but actively growing; their affiliation and seasonal dynamics were similar to the abundant microbes and could not be considered a seed bank. We also showed that the major archaeal groups, Thaumarchaeota Marine Group-I (MGI) and Euryarchaeota Group-II.B (MGII.B) in winter and Euryarchaeota Group-II.A (MGII.A) in summer, contained different ecotypes with varying activities. Our findings suggest that archaeal diversity could be associated with distinct metabolisms or life strategies, and that the rare archaeal biosphere is composed of a complex assortment of organisms with distinct histories that affect their potential for growth.

海洋古菌（Marine Archaea）是微生物浮游生物中的关键类群，对生物地球化学循环具有显著贡献，但目前学界对其群落结构、长期季节活性与动态变化的认知仍存在大量未探明之处。本研究通过焦磷酸测序（pyrosequencing）技术分析16S rDNA与rRNA，对地中海西北部表层水体中丰富生物圈与稀有生物圈（rare biosphere）的年际古菌群落组成进行了监测。对稀有生物圈结构的详细解析显示，稀有古菌群落可划分为三个截然不同的组分：第一组分包含那些在同一生态系统内不同时段可转变为优势类群的稀有古菌，这类古菌通常并非处于休眠状态，我们推测其代表一类具有生态系统特异性的本地种子库，可通过响应季节性环境循环为生态系统功能运转提供必要支撑；第二组分包含在公共数据库中罕见且无活性的古菌细胞，它们属于研究生态系统的外来类群，代表一类潜在定植者的非本地种子库；第三组分包含始终处于稀有状态但处于活跃生长状态的古菌，其分类归属与季节动态与优势微生物类群高度相似，因此不能被视为种子库。本研究同时发现，主要古菌类群——冬季的奇古菌门海洋类群I（Thaumarchaeota Marine Group-I, MGI）与广古菌门II.B类群（Euryarchaeota Group-II.B, MGII.B），以及夏季的广古菌门II.A类群（Euryarchaeota Group-II.A, MGII.A）——均包含活性各异的不同生态型。本研究结果表明，古菌多样性可能与不同的代谢方式或生存策略相关，而稀有古菌生物圈由一系列具有独特演化历史、进而影响其生长潜能的复杂类群所构成。