Laboratoire Microorganismes: Génome et Environnement, Clermont Université Blaise Pascal, UMR CNRS 6023, Aubière, France.
Microb Ecol. 2012 Jul;64(1):67-78. doi: 10.1007/s00248-012-0032-z. Epub 2012 Mar 6.
This study presents an original depth-related survey of virioplankton lytic activity in relation to prokaryotic production and potential protistan bacterivory in the deep (Z(max) = 92 m) meromictic volcanic Lake Pavin (Massif Central, France). The sampling strategy was designed to be representative of the physico-chemical gradients of the water column of the lake, and of the seasonal variability as well, i.e. 12 different depths sampled in triplicates from April to December 2005. In the space, viral lytic activity estimated from the frequency of visibly infected prokaryotic cells and from burst size over the study period generally decreased with depth. This was viewed as a paradox compared to the abundances of viruses and prokaryotes and to the prokaryotic production which increased with depth. The seasonal variability in viral lytic activity was correlated with prokaryotic variables (abundance and production) in the deepest waters, i.e. from the hypolimnion downwards. Compared to previous studies known from the mixolimnion, we conclude that the deep waters in Lake Pavin represent an exclusive environment for heterotrophic prokaryotes whose seasonal activity offers an optimal and unique resource for thriving viral communities, some of which may be typical, endemic to the ambient dark, cold and stable deep water masses. Overall, the main findings in the present study get well around a previous statement that the ecology of the deepest waters of Lake Pavin is essentially driven by the dark viral loop (dissolved organic matter-prokaryotes-viruses) processes, which can sequester organic matters and nutrients for a long-lived turnover time. This is in agreement with recent demonstrations from marine systems that meso- and bathypelagic waters are optimal environments for viral survival and proliferation.
本研究对富营养化分层火山湖 Pavin 湖（法国中央高原）的病毒裂解活性与原核生物生产力和潜在的原生动物噬菌作用的关系进行了深度相关的调查。采样策略旨在代表湖泊水柱的物理化学梯度，并代表季节性变化，即在 2005 年 4 月至 12 月期间，以三倍重复的方式从 12 个不同深度进行采样。在空间上，从可见感染原核细胞的频率和爆发大小估算的病毒裂解活性在整个研究期间通常随深度的增加而降低。与病毒和原核生物的丰度以及与深度增加相关的原核生物生产力相比，这被认为是一个悖论。病毒裂解活性的季节性变化与最深处的原核生物变量（丰度和生产力）相关，即从下混合层向下。与之前在混合层中已知的研究相比，我们得出的结论是，Pavin 湖的深水区代表了异养原核生物的独特环境，其季节性活动为蓬勃发展的病毒群落提供了最佳和独特的资源，其中一些可能是典型的、内生于周围黑暗、寒冷和稳定的深水团。总的来说，本研究的主要发现很好地围绕着先前的一个说法，即 Pavin 湖最深水区的生态学主要受黑暗病毒循环（溶解有机物-原核生物-病毒）过程的驱动，该过程可以将有机物和营养物质隔离，以实现长时间的周转。这与最近来自海洋系统的证明一致，即中层和深海区是病毒生存和增殖的最佳环境。
