Can the Bacterial Community of a High Arctic Glacier Surface Escape Viral Control?
Can the Bacterial Community of a High Arctic Glacier Surface Escape Viral Control?
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DOI：
10.3389/fmicb.2016.00956
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发表时间：
2016
影响因子：
5.2
通讯作者：
Edwards A
中科院分区：
文献类型：
--
作者：
Rassner SM;Anesio AM;Girdwood SE;Hell K;Gokul JK;Whitworth DE;Edwards A
冰川表面代表了一个季节性演变的三维光带，它积累了微生物生物量，并加强了冰融化的正反馈。由于病毒在冰川系统中大量存在，并可能对冰上细菌的产生施加控制，我们研究了资源可获得性的变化是否会促进细菌群落的变化，以及来自斯瓦尔巴群岛冰川光区的融水中病毒和细菌之间的动态。我们的结果表明，在环境营养条件下，低估计的病毒衰减率是细菌生产力的强大病毒控制，在冰上微生物环中引起三分之一的细菌碳的有效病毒分流。此外，病毒颗粒似乎在冰上融化水中非常稳定，这增加了融化中释放的病毒在下游存活的可能性。然而，在实验微观世界中操纵资源的可用性，如溶解的有机碳、氮和磷，表明光区细菌群落可以逃脱病毒的控制。随着细菌产量和数量的增加，病毒与细菌的比率(VBR)显著下降，证明了这一点。焦解测序表明，一些细菌分类群，主要是简氏杆菌属，在源融水和微宇宙群落中都占主导地位。总而言之，我们的结果表明，病毒通过制造坚固的颗粒来保持高VBR以促进与低密度宿主的接触，但这需要进行权衡，从而限制病毒的生产。因此，优势细菌类群似乎利用资源来逃避病毒控制。我们认为，细菌和病毒策略的微妙相互作用影响了冰川上的生物地球化学循环，并最终影响了下游生态系统。
Glacial ice surfaces represent a seasonally evolving three-dimensional photic zone which accumulates microbial biomass and potentiates positive feedbacks in ice melt. Since viruses are abundant in glacial systems and may exert controls on supraglacial bacterial production, we examined whether changes in resource availability would promote changes in the bacterial community and the dynamics between viruses and bacteria of meltwater from the photic zone of a Svalbard glacier. Our results indicated that, under ambient nutrient conditions, low estimated viral decay rates account for a strong viral control of bacterial productivity, incurring a potent viral shunt of a third of bacterial carbon in the supraglacial microbial loop. Moreover, it appears that virus particles are very stable in supraglacial meltwater, raising the prospect that viruses liberated in melt are viable downstream. However, manipulating resource availability as dissolved organic carbon, nitrogen, and phosphorous in experimental microcosms demonstrates that the photic zone bacterial communities can escape viral control. This is evidenced by a marked decline in virus-to-bacterium ratio (VBR) concomitant with increased bacterial productivity and number. Pyrosequencing shows a few bacterial taxa, principally Janthinobacterium sp., dominate both the source meltwater and microcosm communities. Combined, our results suggest that viruses maintain high VBR to promote contact with low-density hosts, by the manufacture of robust particles, but that this necessitates a trade-off which limits viral production. Consequently, dominant bacterial taxa appear to access resources to evade viral control. We propose that a delicate interplay of bacterial and viral strategies affects biogeochemical cycling upon glaciers and, ultimately, downstream ecosystems.