Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 E. Pratt St., Baltimore, MD 21202, USA.
Appl Environ Microbiol. 2011 Nov;77(21):7459-68. doi: 10.1128/AEM.00267-11. Epub 2011 Aug 5.
Despite the increasing knowledge of Synechococcus spp. and their co-occurring cyanophages in oceanic and coastal water, little is known about their abundance, distribution, and interactions in the Chesapeake Bay estuarine ecosystem. A 5-year interannual survey shows that Synechococcus spp. and their phages are persistent and abundant members of Chesapeake Bay microbial communities. Synechococcus blooms (10⁶ cells ml⁻¹) were often observed in summer throughout the Bay, contributing 20 to 40% of total phytoplankton chlorophyll a. The distribution of phycoerythrin-containing (PE-rich) Synechococcus cells appeared to mostly correlate with the salinity gradient, with higher abundances at higher salinities. Cyanophages infectious to Synechococcus were also abundant (up to 6 × 10⁵ viruses ml⁻¹ by the most probable number assay) during summer months in the Bay. The covariation in abundance of Synechococcus spp. and cyanophages was evident, although the latitude of observed positive correlation varied in different years, mirroring the changing environmental conditions and therefore the host-virus interactions. The impacts of cyanophages on host Synechococcus populations also varied spatially and temporally. Higher phage-related Synechococcus mortality was observed in drought years. Virus-mediated host mortality and subsequent liberation of dissolved organic matter (DOM) may substantially influence oceanic biogeochemical processing through the microbial loop as well as the microbial carbon pump. These observations emphasize the influence of environmental gradients on natural Synechococcus spp. and their phage population dynamics in the estuarine ecosystem.
尽管人们对海洋和沿海水域中的聚球藻属及其共生的噬藻体有了越来越多的了解，但对于它们在切萨皮克湾河口生态系统中的丰度、分布和相互作用知之甚少。一项为期 5 年的年度调查表明，聚球藻属及其噬菌体是切萨皮克湾微生物群落中持久且丰富的成员。夏季整个海湾经常出现聚球藻属水华（10⁶ 个细胞 ml⁻¹），占总浮游植物叶绿素 a 的 20%至 40%。含有藻红蛋白（PE 丰富）的聚球藻细胞的分布似乎主要与盐度梯度相关，在高盐度下丰度更高。夏季噬藻体能感染聚球藻的噬菌体也很丰富（通过最可能数法检测到高达 6×10⁵ 个病毒 ml⁻¹）。聚球藻属和噬藻体的丰度变化明显，尽管在不同年份观察到的正相关的纬度不同，反映了不断变化的环境条件和因此宿主-病毒相互作用。噬藻体对宿主聚球藻种群的影响也具有时空变异性。在干旱年份观察到与噬菌体相关的聚球藻死亡率更高。病毒介导的宿主死亡和随后释放的溶解有机物质（DOM）可能通过微生物环以及微生物碳泵对海洋生物地球化学过程产生重大影响。这些观察结果强调了环境梯度对河口生态系统中自然聚球藻属及其噬菌体种群动态的影响。
