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Influence of the polar light cycle on seasonal dynamics of an Antarctic lake microbial community.
Microbiome ( IF 15.5 ) Pub Date : 2020-08-09 , DOI: 10.1186/s40168-020-00889-8
Pratibha Panwar 1 , Michelle A Allen 1 , Timothy J Williams 1 , Alyce M Hancock 1, 2 , Sarah Brazendale 1, 3 , James Bevington 1 , Simon Roux 4 , David Páez-Espino 4, 5 , Stephen Nayfach 4 , Maureen Berg 4 , Frederik Schulz 4 , I-Min A Chen 4 , Marcel Huntemann 4 , Nicole Shapiro 4 , Nikos C Kyrpides 4 , Tanja Woyke 4 , Emiley A Eloe-Fadrosh 4 , Ricardo Cavicchioli 1
Affiliation  

Cold environments dominate the Earth’s biosphere and microbial activity drives ecosystem processes thereby contributing greatly to global biogeochemical cycles. Polar environments differ to all other cold environments by experiencing 24-h sunlight in summer and no sunlight in winter. The Vestfold Hills in East Antarctica contains hundreds of lakes that have evolved from a marine origin only 3000–7000 years ago. Ace Lake is a meromictic (stratified) lake from this region that has been intensively studied since the 1970s. Here, a total of 120 metagenomes representing a seasonal cycle and four summers spanning a 10-year period were analyzed to determine the effects of the polar light cycle on microbial-driven nutrient cycles. The lake system is characterized by complex sulfur and hydrogen cycling, especially in the anoxic layers, with multiple mechanisms for the breakdown of biopolymers present throughout the water column. The two most abundant taxa are phototrophs (green sulfur bacteria and cyanobacteria) that are highly influenced by the seasonal availability of sunlight. The extent of the Chlorobium biomass thriving at the interface in summer was captured in underwater video footage. The Chlorobium abundance dropped from up to 83% in summer to 6% in winter and 1% in spring, before rebounding to high levels. Predicted Chlorobium viruses and cyanophage were also abundant, but their levels did not negatively correlate with their hosts. Over-wintering expeditions in Antarctica are logistically challenging, meaning insight into winter processes has been inferred from limited data. Here, we found that in contrast to chemolithoautotrophic carbon fixation potential of Southern Ocean Thaumarchaeota, this marine-derived lake evolved a reliance on photosynthesis. While viruses associated with phototrophs also have high seasonal abundance, the negative impact of viral infection on host growth appeared to be limited. The microbial community as a whole appears to have developed a capacity to generate biomass and remineralize nutrients, sufficient to sustain itself between two rounds of sunlight-driven summer-activity. In addition, this unique metagenome dataset provides considerable opportunity for future interrogation of eukaryotes and their viruses, abundant uncharacterized taxa (i.e. dark matter), and for testing hypotheses about endemic species in polar aquatic ecosystems.

中文翻译:

极光周期对南极湖微生物群落季节动态的影响。

寒冷的环境主导着地球的生物圈,微生物活动推动了生态系统的进程,从而极大地促进了全球生物地球化学循环。极地环境与所有其他寒冷环境不同,夏季会经历24小时的阳光照射,而冬季则不会阳光照射。南极东部的Vestfold丘陵包含数百个湖泊,这些湖泊仅在3000-7000年前就从海洋起源而来。自从1970年代以来,Ace湖是该地区的莫莫克(分层)湖。在这里,共分析了代表季节周期的120个元基因组和跨越10年周期的四个夏天,以确定极光周期对微生物驱动的营养周期的影响。湖泊系统的特点是硫和氢循环复杂,尤其是在缺氧层中,具有多种机制来降解整个水柱中存在的生物聚合物。最丰富的两个分类单元是光养生物(绿硫细菌和蓝细菌),它们受阳光的季节性可用性影响很大。水下录像中捕获了夏季在界面上形成的绿皮草生物量的程度。彩叶菌的丰度从夏季的83%下降到冬季的6%和春季的1%,然后反弹到高水平。预测的绿球藻病毒和噬菌体也很丰富,但它们的水平与宿主之间没有负相关。在南极洲,越冬探险在逻辑上是一项挑战,这意味着从有限的数据可以推断出对冬季过程的洞察力。这里,我们发现,与南部海洋Thaumarchaeota的化石自养碳固定潜力相反,该海洋来源的湖泊进化出了对光合作用的依赖。尽管与光养细菌相关的病毒也具有很高的季节性丰度,但病毒感染对宿主生长的负面影响似乎是有限的。整个微生物群落似乎已经发展出产生​​生物质和再矿化养分的能力,足以在两轮阳光驱动的夏季活动之间维持自身。此外,这个独特的元基因组数据集为将来的真核生物及其病毒,丰富的未分类生物(即暗物质)的研究以及检验极地水生生态系统中特有物种的假设提供了相当大的机会。这个源自海洋的湖泊发展了对光合作用的依赖。虽然与光养细菌相关的病毒也具有很高的季节性丰度,但病毒感染对宿主生长的负面影响似乎是有限的。整个微生物群落似乎已经发展出产生​​生物质和再矿化养分的能力,足以在两轮阳光驱动的夏季活动之间维持自身。此外,这个独特的元基因组数据集为将来的真核生物及其病毒,丰富的未分类生物(即暗物质)的研究以及检验极地水生生态系统中特有物种的假设提供了相当大的机会。这个源自海洋的湖泊发展了对光合作用的依赖。尽管与光养细菌相关的病毒也具有很高的季节性丰度,但病毒感染对宿主生长的负面影响似乎是有限的。整个微生物群落似乎已经发展出产生​​生物质和再矿化养分的能力,足以在两轮阳光驱动的夏季活动之间维持自身。另外,这个独特的元基因组数据集为将来的真核生物及其病毒,丰富的未分类的类群(即暗物质)的研究以及检验极地水生生态系统中特有物种的假设提供了巨大的机会。病毒感染对宿主生长的负面影响似乎是有限的。整个微生物群落似乎已经发展出产生​​生物质和再矿化养分的能力,足以在两轮阳光驱动的夏季活动之间维持自身。另外,这个独特的元基因组数据集为将来的真核生物及其病毒,丰富的未分类的类群(即暗物质)的研究以及检验极地水生生态系统中特有物种的假设提供了巨大的机会。病毒感染对宿主生长的负面影响似乎是有限的。整个微生物群落似乎已经发展出产生​​生物质和再矿化养分的能力,足以在两轮阳光驱动的夏季活动之间维持自身。此外,这个独特的元基因组数据集为将来的真核生物及其病毒,丰富的未分类生物(即暗物质)的研究以及检验极地水生生态系统中特有物种的假设提供了相当大的机会。
更新日期:2020-08-10
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