Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.
School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
FEMS Microbiol Ecol. 2017 Jun 1;93(6). doi: 10.1093/femsec/fix070.
Thraustochytrids are unicellular fungi-like (heterotrophic) marine protists that have long been considered to play an important role in the biogeochemical cycles of the coastal oceans. However, the significance of their ecological functions and their diversity in marine ecosystems remain largely unknown. In this report, we examined the spatial and temporal variations of planktonic thraustochytrids, their relationship with other environmental factors, and their diversity in the subtropical coastal waters of China. The abundance of planktonic thraustochytrids ranged from 2.56 × 105 to 17.57 × 105 cells L-1 with highest abundance detected in polluted coastal water in the Spring (March) season. The thraustochytrid biomass was greater than the bacterial biomass in most seawater samples, ranging from 32.29 to 359.51% that of bacterioplankton. The abundance of thraustochytrids appeared to be largely related to that of bacterioplankton and to chemical oxygen demand in water columns. High-throughput sequencing analyses revealed a total of 105 OTUs (97% similarity), which were members of genera Thraustochytrium, Aplanochytrium, Oblongichytrium, Ulkenia, Labyrinthula and undescribed novel phylotypes. Results of this study indicated unprecedented high diversity of labyrinthulomycetes as well as the presence of novel labyrinthulomycete and thraustochytrid lineages, and also provided new information on the significant role of thraustochytrids in microbial food webs in a coastal marine ecosystem.
束丝藻目真菌是一种类似单细胞真菌的（异养）海洋原生生物，长期以来被认为在沿海海洋的生物地球化学循环中发挥着重要作用。然而，它们的生态功能的重要性及其在海洋生态系统中的多样性在很大程度上仍然未知。在本报告中，我们研究了浮游束丝藻目真菌的时空变化、它们与其他环境因素的关系以及它们在中国亚热带沿海水域的多样性。浮游束丝藻目真菌的丰度范围为 2.56×105 到 17.57×105 个细胞 L-1，春季（三月）在污染沿海水中检测到的丰度最高。在大多数海水样本中，束丝藻目真菌的生物量大于细菌的生物量，范围从细菌浮游生物的 32.29%到 359.51%。束丝藻目真菌的丰度似乎主要与细菌丰度和水柱中的化学需氧量有关。高通量测序分析共揭示了 105 个 OTUs（相似度为 97%），它们是束丝藻属、拟束丝藻属、扁束丝藻属、弯角藻属、Labyrinthula 和未描述的新的丝状真菌属的成员。本研究结果表明，海洋涡鞭毛藻具有前所未有的高多样性，并且存在新型海洋涡鞭毛藻和束丝藻目真菌谱系，也为束丝藻目真菌在沿海海洋生态系统中的微生物食物网中发挥的重要作用提供了新信息。
