Yang Yanhui, Nagata Toshi
Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan.
Front Microbiol. 2021 Nov 18;12:774849. doi: 10.3389/fmicb.2021.774849. eCollection 2021.
Viral production is a key parameter for assessing virus-mediated biogeochemical cycles. One widely used method for the determination of viral production, called the virus reduction assay, reduces viral abundance, while maintaining bacterial abundance, using 0.2-μm pore-size filters. Viral production is estimated from the increase of viral abundance during incubation. We hypothesized that small-cell-sized bacterial communities can pass through 0.2-μm filters and drive viral production, representing a missing fraction of viral production that is missed by the virus reduction assay. Coastal seawater was filtered through 0.2-μm filters and diluted with virus-free seawater. Viral production in the <0.2-μm filtrate was estimated from changes in viral abundance determined through flow cytometry. We found that viruses were produced in the <0.2-μm communities, which were strongly enriched with low nucleic acid content bacteria. Estimated viral production in the <0.2-μm filtrates accounted for up to 43% of total viral production and 10% of dissolved organic carbon production mediated by viral lysis of bacterial cells. By not considering viral production in these <0.2-μm communities, the virus reduction assay may underestimate viral production. Virus-bacteria interactions in <0.2-μm communities may represent a significant and overlooked role of viruses in marine food webs and carbon fluxes.
病毒产生是评估病毒介导的生物地球化学循环的关键参数。一种广泛用于测定病毒产生的方法，称为病毒减少测定法，使用孔径为0.2μm的滤膜在保持细菌丰度的同时降低病毒丰度。病毒产生量通过培养过程中病毒丰度的增加来估算。我们假设小细胞大小的细菌群落可以通过0.2μm的滤膜并驱动病毒产生，这代表了病毒减少测定法遗漏的病毒产生的一部分。将沿海水通过0.2μm的滤膜过滤，并用无病毒海水稀释。通过流式细胞术测定的病毒丰度变化来估算<0.2μm滤液中的病毒产生量。我们发现<0.2μm的群落中产生了病毒，这些群落中富含低核酸含量的细菌。<0.2μm滤液中估算的病毒产生量占病毒总产生量的43%，占细菌细胞病毒裂解介导的溶解有机碳产生量的10%。由于未考虑这些<0.2μm群落中的病毒产生，病毒减少测定法可能会低估病毒产生量。<0.2μm群落中的病毒-细菌相互作用可能代表了病毒在海洋食物网和碳通量中一个重要但被忽视的作用。
