Lu Xinxin, Sun Shulei, Zhang Yu-Qin, Hollibaugh James T, Mou Xiaozhen
Department of Biological Sciences, Kent State University, Kent, Ohio, USA.
Center for Advanced Laboratory Medicine, University of California, San Diego, La Jolla, California, USA.
Appl Environ Microbiol. 2015 Feb;81(3):910-7. doi: 10.1128/AEM.02802-14. Epub 2014 Nov 21.
Large spatial scales and long-term shifts of bacterial community composition (BCC) in the open ocean can often be reliably predicted based on the dynamics of physical-chemical variables. The power of abiotic factors in shaping BCC on shorter time scales in shallow estuarine mixing zones is less clear. We examined the diurnal variation in BCC at different water depths in the spring and fall of 2011 at a station in the Gray's Reef National Marine Sanctuary (GRNMS). This site is located in the transition zone between the estuarine plume and continental shelf waters of the South Atlantic Bight. A total of 234,516 pyrotag sequences of bacterial 16S rRNA genes were recovered; they were taxonomically affiliated with >200 families of 23 bacterial phyla. Nonmetric multidimensional scaling analysis revealed significant differences in BCC between spring and fall samples, likely due to seasonality in the concentrations of dissolved organic carbon and nitrate plus nitrite. Within each diurnal sampling, BCC differed significantly by depth only in the spring and differed significantly between day and night only in the fall. The former variation largely tracked changes in light availability, while the latter was most correlated with concentrations of polyamines and chlorophyll a. Our results suggest that at the GRNMS, a coastal mixing zone, diurnal variation in BCC is attributable to the mixing of local and imported bacterioplankton rather than to bacterial growth in response to environmental changes. Our results also indicate that, like members of the Roseobacter clade, SAR11 bacteria may play an important role in processing dissolved organic material in coastal oceans.
基于物理化学变量的动态变化，通常能够可靠地预测公海中细菌群落组成（BCC）的大空间尺度和长期变化。在浅海河口混合区较短时间尺度上，非生物因素对塑造BCC的作用尚不清楚。我们于2011年春季和秋季在格雷礁国家海洋保护区（GRNMS）的一个站点，研究了不同水深BCC的日变化。该站点位于南大西洋湾河口羽流与大陆架水域的过渡区。共获得了234,516条细菌16S rRNA基因的焦磷酸测序序列；它们在分类学上隶属于23个细菌门的200多个科。非度量多维标度分析显示，春季和秋季样本的BCC存在显著差异，这可能是由于溶解有机碳和硝酸盐加亚硝酸盐浓度的季节性变化所致。在每次日采样中，BCC仅在春季随深度有显著差异，仅在秋季白天和夜晚之间有显著差异。前者的变化很大程度上跟踪了光照可用性的变化，而后者与多胺和叶绿素a的浓度相关性最高。我们的结果表明，在GRNMS这个沿海混合区，BCC的日变化归因于本地和外来浮游细菌的混合，而非细菌对环境变化的生长响应。我们的结果还表明，与玫瑰杆菌属分支成员一样，SAR11细菌可能在沿海海洋溶解有机物质的处理中发挥重要作用。
