Antarctic Marine Archaebacteria; Biological Properties and Ecological Significance

Delong 9418442古细菌是一种进化上独特的原核生物。直到最近，人们还认为古细菌只在少数不同的生态位中茁壮成长，这些生态位要么是非常热的，要么是非常咸的，要么是严格的厌氧环境。最近的研究表明，在南极洲帕尔默站附近的沿海水域，远洋海洋古细菌可以构成南极原核生物生物量的主要部分（30%）。由于帕尔默站附近的地表水产生了迄今为止最高的远洋古细菌生物量，因此该地区非常适合研究这些不寻常的微生物。本研究的主要目的是研究南极安弗斯岛沿海水域中上层海洋古细菌的生态意义、分布和丰度以及代谢和生理活动。分子生物学技术将用于量化南极海洋古细菌物种的时空丰度和变异性。将开发高灵敏度、半自动化的方法来定量野外样品中古细菌群和物种特异性核糖体RNA和DNA。为了更好地了解它们的生理活动，将采用“王国特异性”代谢抑制剂的方法来估计远洋古细菌对原核生物总异养活性的贡献。该项目将提供关于南极远洋古细菌的季节和空间变化的信息，这些古细菌可以构成南极沿海原核生物生物量的主要部分。最后，该项目还将加深对南极沿海水域丰富的“古浮游生物”的生物地球化学活动和生态作用的认识，并可能为它们对南极独特环境的特定适应提供线索。

Delong 9418442 Archaebacteria are an evolutionarily distinct group of prokaryotes. Until very recently, archaebacteria were thought to thrive only in a few disparate niches, consisting of either very hot, very salty, or strictly anaerobic environments. Recent studies show that pelagic marine archaebacteria can constitute a major fraction (30%) of Antarctic prokaryote biomass in coastal waters off Palmer Station, Antarctica. Since surface waters off Palmer Station have yielded the highest biomass estimates of pelagic archaebacteria to date, this area is uniquely suited for studing these unusual microorganisms. The main objective of the proposed work is to characterize the ecological significance, distribution and aboundance, and the metabolic and physiological activities, of pelagic marine archaebacteria in coastal waters off Anvers Island, Antarctica. Molecular biological techniques will be used to quantify the spatial and temporal abundance and variability of Antarctic marine archaebacterial species. Highly sensitive, semiautomated methods will be developed to quantify archaebacterial group and species-specific ribosomal RNA and DNA in field samples. To better understand their physiological activities, methods employing "kingdom-specific" metabolic inhibitors will be used to estimate the contribution of pelagic archaebacteria to total prokaryotic heterotrophic activity. The project will provide information on the seasonal and spatial variability of pelagic Antarctic archaebacteria, which can comprise a major fraction of Antarctic coastal prokarytoic biomass. Finally, this project will also enhance understanding of the biogeochemical activities and ecological roles of these abundant "archaeoplankton" in coastal Antarctic waters, and may provide clues as to their specific adaptations to the unique Antarctic environment.