Colangelo-Lillis Jesse, Wing Boswell A, Raymond-Bouchard Isabelle, Whyte Lyle G
Department of Earth and Planetary Science, McGill University, MontrealQC, Canada; McGill Space Institute, McGill University, MontrealQC, Canada.
Department of Natural Resource Science, McGill University, Montreal QC, Canada.
Front Microbiol. 2017 Jan 23;7:2158. doi: 10.3389/fmicb.2016.02158. eCollection 2016.
Viruses are a primary influence on microbial mortality in the global ocean. The impacts of viruses on their microbial hosts in low-energy environments are poorly explored and are the focus of this study. To investigate the role of viruses in mediating mortality in low-energy environments where contacts between viruses and microbes are infrequent, we conducted a set of time series incubations in the outlet and channel sediments of two cold, hypersaline springs of the Canadian High Arctic. We found microbial and viral populations in dynamic equilibrium, indicating approximately equal birth and death rates for each population. rates of microbial growth were low (0.5-50 × 10 cells cm h) as were rates of viral decay (0.09-170 × 10 virions cm h). A large fraction of the springs' viral communities (49-100%) were refractory to decay over the timescales of our experiments. Microcosms amended with lactate or acetate exhibited increased microbial growth rates (up to three-fold) indicating organic carbon as one limiting resource for the microbial communities in these environments. A substantial fraction (15-71%) of the microbial populations contained inducible proviruses that were released- occasionally in multiple pulses- over the eight monitored days following chemical induction. Our findings indicate that viruses in low-energy systems maintain low rates of production and activity, have a small but notable impact on microbial mortality (8-29% attenuation of growth) and that successful viral replication may primarily proceed by non-lethal strategies. In cold, low biomass marine systems of similar character (e.g., subsurface sediments), viruses may be a relatively minor driver of community mortality compared to less energy-limited environments such as the marine water column or surface sediments.
病毒是全球海洋中微生物死亡的主要影响因素。在低能量环境中，病毒对其微生物宿主的影响鲜有研究，而这正是本研究的重点。为了探究病毒在介导低能量环境中死亡率方面的作用，在这种环境中病毒与微生物之间的接触很少，我们在加拿大北极地区两个寒冷、高盐度泉的出口和通道沉积物中进行了一系列时间序列培养实验。我们发现微生物和病毒种群处于动态平衡，这表明每个种群的出生率和死亡率大致相等。微生物生长速率较低（0.5 - 50×10个细胞·厘米⁻³·小时⁻¹），病毒衰减速率也较低（0.09 - 170×10个病毒粒子·厘米⁻³·小时⁻¹）。在我们实验的时间尺度上，大部分泉水中的病毒群落（49 - 100%）难以衰减。用乳酸盐或醋酸盐改良的微观世界显示微生物生长速率增加（高达三倍），这表明有机碳是这些环境中微生物群落的一种限制资源。在化学诱导后的八个监测日中，相当一部分（15 - 71%）的微生物种群含有可诱导的原病毒，这些原病毒会偶尔以多个脉冲的形式释放出来。我们的研究结果表明，低能量系统中的病毒维持着较低的产生和活动速率，对微生物死亡率有微小但显著的影响（生长衰减8 - 29%），并且成功的病毒复制可能主要通过非致死策略进行。在具有类似特征的寒冷、低生物量海洋系统（如地下沉积物）中，与海洋水柱或表层沉积物等能量限制较少的环境相比，病毒可能是群落死亡率的相对次要驱动因素。
