Viruses play an important role in the ecology and biogeochemistry of marine ecosystems. Beyond mortality and gene transfer, viruses can reprogram microbial metabolism during infection by expressing auxiliary metabolic genes (AMGs) involved in photosynthesis, central carbon metabolism, and nutrient cycling. While previous studies have focused on AMG diversity in the sunlit and dark ocean, less is known about the role of viruses in shaping metabolic networks along redox gradients associated with marine oxygen minimum zones (OMZs). Here, we analyzed relatively quantitative viral metagenomic datasets that profiled the oxygen gradient across Eastern Tropical South Pacific (ETSP) OMZ waters, assessing whether OMZ viruses might impact nitrogen (N) cycling via AMGs. Identified viral genomes encoded six N-cycle AMGs associated with denitrification, nitrification, assimilatory nitrate reduction, and nitrite transport. The majority of these AMGs (80%) were identified in T4-like Myoviridae phages, predicted to infect Cyanobacteria and Proteobacteria, or in unclassified archaeal viruses predicted to infect Thaumarchaeota. Four AMGs were exclusive to anoxic waters and had distributions that paralleled homologous microbial genes. Together, these findings suggest viruses modulate N-cycling processes within the ETSP OMZ and may contribute to nitrogen loss throughout the global oceans thus providing a baseline for their inclusion in the ecosystem and geochemical models.

病毒在海洋生态系统的生态学和生物地球化学中发挥着重要作用。除了死亡率和基因转移之外，病毒还可以通过表达参与光合作用、中心碳代谢和营养循环的辅助代谢基因 (AMG) 来重新编程感染期间的微生物代谢。虽然之前的研究主要集中在阳光照射和黑暗海洋中的 AMG 多样性，但人们对病毒在沿着与海洋最低氧区 (OMZ) 相关的氧化还原梯度形成代谢网络中的作用知之甚少。在这里，我们分析了相对定量的病毒宏基因组数据集，这些数据集描绘了东热带南太平洋 (ETSP) OMZ 水域的氧梯度，评估 OMZ 病毒是否可能通过 AMG 影响氮 (N) 循环。已鉴定的病毒基因组编码了六个与反硝化作用相关的 N 循环 AMG，硝化作用、同化硝酸盐还原和亚硝酸盐运输。这些 AMG 中的大多数 (80%) 在 T4 样Myoviridae噬菌体，预计会感染蓝藻和变形菌，或未分类的古细菌病毒预计会感染Thaumarchaeota。四个 AMG 专用于缺氧水域，并且具有与同源微生物基因平行的分布。总之，这些发现表明病毒调节 ETSP OMZ 内的氮循环过程，并可能导致全球海洋中的氮流失，从而为它们纳入生态系统和地球化学模型提供了基线。