Distribution of Capsulated Bacterioplankton in the North Atlantic and North Sea
Distribution of Capsulated Bacterioplankton in the North Atlantic and North Sea
复制标题
北大西洋和北海有荚膜浮游细菌的分布
作者：
K. Stoderegger;G. Herndl
在实验室实验中，浮游细菌培养在不同的营养条件下，并表现出多糖胶囊（胶囊化细菌）和CTC（氯化氰四唑）阳性，因此代谢高度活跃的细菌的细菌的百分比进行了测定。在这些海水培养物与营养物质修正超过95%的CTC阳性细胞表现出胶囊。在两次巡航中，一次到北大西洋，一次到北海，我们调查了整个水柱中被包裹的细菌的分布。富营养化的表层沃茨中的被膜细菌通常比深层或贫营养区中的被膜细菌更丰富。在北大西洋上层100 m处，约6-14%的浮游细菌群落被包囊化，而在100 m以下的水层中，97%的细菌缺乏可见的包囊。被囊化细菌的百分比与细菌丰度和产量以及叶绿素a浓度相关。此外，DOC（溶解有机碳）的生物利用度，估计细菌产量和DOC浓度之间的比例，显着相关的被包裹的细菌的百分比。在北海，从表层（3 m深度）到近底层（25-35 m），被囊细菌对细菌总数的贡献从20%下降到14%。在北海的近岸区域，约27%的细菌显示出荚膜。总体而言，一个显着减少的贡献，胶囊细菌的总细菌丰度是检测到从富营养化的沿海环境开放的北大西洋。因此，使用这种基于落射荧光的技术来计数被胶囊化的浮游细菌，使我们能够定期评估即使在海洋水柱中被胶囊化的细菌的数量。基于在这项研究中获得的数据，我们得出结论，几乎所有的代谢活性高的细菌表现出胶囊，但也有一些代谢活性较低的细胞表达多糖胶囊检测与此方法。
In laboratory experiments, bacterioplankton were incubated under different nutrient conditions, and the percentage of bacteria exhibiting a polysaccharidic capsule (capsulated bacteria) and that of CTC (cyanotetrazolium chloride)-positive and therefore metabolically highly active bacteria were determined. In these seawater cultures amended with nutrients more than 95% of the CTC-positive cells exhibited a capsule. During two cruises, one to the North Atlantic and one to the North Sea, we investigated the distribution of capsulated bacteria throughout the water column. Capsulated bacteria were generally more abundant in eutrophic surface waters than in deeper layers or more oligotrophic regions. In the upper 100 m of the North Atlantic, about 6–14% of the total bacterioplankton community was capsulated, while in the layers below 100 m depth, 97% of the bacteria lacked a visible capsule. The percentage of capsulated bacteria correlated with bacterial abundance and production, and chlorophyll a concentration. Also, the bioavailability of DOC (dissolved organic carbon), estimated by the ratio between bacterial production and DOC concentration, significantly correlated with the percentage of capsulated bacteria. In the North Sea, the contribution of capsulated bacteria to the total number of bacteria decreased from the surface (3 m depth) to the near-bottom (25–35 m) layers from 20% to 14% capsulated bacteria. In the nearshore area of the North Sea, about 27% of the bacteria exhibited a capsule. Overall, a pronounced decrease in the contribution of capsulated bacteria to the total bacterial abundance was detectable from the eutrophic coastal environment to the open North Atlantic. Using this epifluorescence-based technique to enumerate capsulated bacterioplankton thus allowed us to routinely assess the number of capsulated bacteria even in the oceanic water column. Based on the data obtained in this study we conclude that almost all metabolically highly active bacteria exhibit a capsule, but also some of the metabolically less active cells express a polysaccharide capsule detectable with this method.