Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, TN 37996, USA.
Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, TN 37996, USA.
Sci Total Environ. 2021 Sep 15;787:147589. doi: 10.1016/j.scitotenv.2021.147589. Epub 2021 May 12.
Previous research has revealed the ecological importance of viruses in different ecosystems. However, bacteriophage-host distribution patterns in soil depth profiles have not been investigated. Environmental factors such as nutrient availability and physiological stress can impact the mode (either lytic or lysogenic) of viral reproduction and subsequent influence of virus infection on ecological processes. Soil depth profiles with distinct geochemical properties are ideal models to investigate the virus-host relationships as a function of environmental trophic status and cell abundance. Batch enrichment experiments using soil collected at varying depths (0-140 cm) as inoculum were performed to explore the interactions between viruses and co-occurring microbial hosts under nutrient stimulation. Both viral and bacterial abundance increased in the nutrient media compared with those in the original soils. Bacterial abundance was similar in mixed-cultures of soils regardless of sampling depth, whereas viral abundance was negatively correlated with the depth of soil samples which caused a decreasing virus-to-bacteria ratio. The lysogenetic fraction increased with soil depth in a similar manner as in the original soils assessed directly without nutrient stimulation. The bacterial diversity decreased with soil depth, and was influenced primarily by soil type, viral abundance, and virus-to-bacteria ratio. The bacterial communities were dominated by Bacilli, Beta-, Gamma-Proteobacteria, and Clostridia after nutrient stimulation. Viral and bacterial community structure also varied with soil horizons (i.e., depth). The results showed that the patterns for virus-host interactions shaped by the geochemical properties in the original environment were conserved or similar after in vitro nutrient stimulation. These findings suggest that short-term changes in trophic status alone may not significantly alter the balance of viral reproductive strategies in terrestrial ecosystems as in the antecedent environmental conditions that the host community has long adapted to, and other factors such as stress, host diversity or adaptation may be necessary to trigger community-level shifts in the interactions between viruses and hosts that responded most favorably to nutrient addition.
先前的研究揭示了病毒在不同生态系统中的生态重要性。然而，土壤深度剖面中噬菌体-宿主的分布模式尚未得到研究。环境因素，如养分的可利用性和生理压力，会影响病毒繁殖的模式（裂解或溶原），进而影响病毒感染对生态过程的影响。具有不同地球化学性质的土壤深度剖面是研究病毒-宿主关系的理想模型，因为它们可以作为环境营养状态和细胞丰度的函数。使用不同深度（0-140cm）采集的土壤作为接种物进行批量富集实验，以在营养刺激下探索病毒和共存微生物宿主之间的相互作用。与原始土壤相比，在营养培养基中，病毒和细菌的丰度都增加了。混合培养的土壤中细菌丰度相似，而与采样深度无关，而病毒丰度与土壤样本的深度呈负相关，导致病毒与细菌的比例下降。溶原性部分与原始土壤中没有营养刺激的直接评估一样，随着土壤深度的增加而增加。随着土壤深度的增加，细菌多样性下降，主要受土壤类型、病毒丰度和病毒与细菌的比例影响。在营养刺激后，细菌群落主要由芽孢杆菌、β-变形菌、γ-变形菌和梭菌组成。病毒和细菌群落结构也随土壤层（即深度）而变化。结果表明，在体外营养刺激后，由原始环境地球化学性质塑造的病毒-宿主相互作用模式保持不变或相似。这些发现表明，单独的营养状态的短期变化可能不会显著改变陆地生态系统中病毒繁殖策略的平衡，因为宿主群落已经长期适应了先前的环境条件，而其他因素，如压力、宿主多样性或适应性，可能需要触发病毒和宿主之间的群落水平变化，这些变化对营养添加的反应最有利。
