Hewson Ian, Fuhrman Jed A
Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale Pkwy AHF 107, Los Angeles, CA 90089-0371, USA.
Microb Ecol. 2007 May;53(4):631-8. doi: 10.1007/s00248-006-9148-3. Epub 2007 Mar 8.
Viruses cause significant mortality of marine microorganisms; however, their role in shaping the composition of microbial assemblages has not been fully elucidated. Because viruses may form lysogenic relationships with their hosts, temperate viruses may influence bacterial assemblage structures through direct lysis of hosts when induced by environmental stimuli or by homoimmunity (i.e., immunity to closely related viruses). We investigated the components of bacterioplankton assemblages that bore prophage using the lysogenic induction agent mitomycin C. Seawater was collected at two locations (the San Pedro Ocean Time Series Station and in the Santa Barbara Channel) in the Southern California Borderland and amended with mitomycin C. After 24-h incubation, the community structure of bacterioplankton was compared with unamended controls using automated rRNA intergenic spacer analysis. The addition of mitomycin C to seawater had effects on the community structure of bacterioplankton, stimulating detectable overall diversity and richness of fingerprints and causing the assemblages within incubations to become different to control assemblages. Most negatively impacted operational taxonomic units (OTU) in mitomycin C-amended incubations individually comprised a large fraction of total amplified DNA in initial seawater (5.3-23.3% of amplified DNA fluorescence) fingerprints, and data suggest that these include organisms putatively classified as members of the gamma-Proteobacteria, SAR11 cluster, and Synechococcus groups. The stimulation of assemblage richness by induction of lysogens, and the reduction in the contribution to total DNA of common OTU (and concomitant increase in rare OTU), suggests that temperate phage have the potential to strongly influence the diversity of bacterioplankton assemblages. Because lysogenic OTU may also be resistant to closely related lytic (i.e., free-living) viruses, the impact of lytic virioplankton on assemblages may only be pronounced transiently or when conditions causing lysogenic induction arise.
病毒导致海洋微生物大量死亡；然而，它们在塑造微生物群落组成方面的作用尚未完全阐明。由于病毒可能与其宿主形成溶原性关系，温和噬菌体可能在受到环境刺激或通过同源免疫（即对密切相关病毒的免疫）诱导时，通过直接裂解宿主来影响细菌群落结构。我们使用溶原诱导剂丝裂霉素C研究了带有前噬菌体的浮游细菌群落的组成部分。在南加州边境地区的两个地点（圣佩德罗海洋时间序列站和圣巴巴拉海峡）采集海水，并用丝裂霉素C进行处理。孵育24小时后，使用自动rRNA基因间隔区分析将浮游细菌的群落结构与未处理的对照进行比较。向海水中添加丝裂霉素C对浮游细菌的群落结构产生了影响，刺激了指纹图谱中可检测到的总体多样性和丰富度，并使孵育中的群落与对照群落变得不同。在丝裂霉素C处理的孵育中，受影响最大的操作分类单元（OTU）各自在初始海水中的总扩增DNA（扩增DNA荧光的5.3 - 23.3%）指纹图谱中占很大比例，数据表明这些包括被推测归类为γ-变形菌纲、SAR11簇和聚球藻属群体成员的生物。通过诱导溶原菌刺激群落丰富度，以及常见OTU对总DNA贡献的减少（以及稀有OTU的相应增加），表明温和噬菌体有可能强烈影响浮游细菌群落的多样性。由于溶原性OTU也可能对密切相关的裂解性（即自由生活的）病毒具有抗性，裂解性浮游病毒对群落的影响可能仅在短期内显著，或者在导致溶原诱导的条件出现时才会显著。
