Jonas Robert B, Tuttle Jon H, Stoner Daphne L, Ducklow Hugh W
Department of Biology, George Mason University, Fairfax, Virginia 22030, University of Maryland Center for Environmental and Estuarine Studies, Chesapeake Biological Laboratory, Solomons, Maryland 20688-0038, and Horn Point Environmental Laboratory, Cambridge, Maryland 21613-0775.
Appl Environ Microbiol. 1988 Mar;54(3):791-798. doi: 10.1128/aem.54.3.791-798.1988.
Bacterial production and amino acid metabolism in aquatic systems can be estimated by simultaneous incubation of water samples with both tritiated methyl-thymidine and C-labeled amino acids. This dual-label method not only saves time, labor, and materials, but also allows determination of these two parameters in the same microbial subcommunity. Both organic carbon incorporation and respiration can be estimated. The results obtained with the dual-label technique are not significantly different from single-radiolabel methods over a wide range of bacterial activity. The method is particularly suitable for large-scale field programs and has been used successfully with eutrophic estuarine samples as well as with oligotrophic oceanic water. In the mesohaline portion of Chesapeake Bay, thymidine incorporation ranged seasonally from 2 to 635 pmol liter h and amino acid turnover rates ranged from 0.01 to 28.4% h. Comparison of thymidine incorporation with amino acid turnover measurements made at a deep, midbay station in 1985 suggested a close coupling between bacterial production and amino acid metabolism during most of the year. However, production-specific amino acid turnover rates increased dramatically in deep bay waters during the spring phytoplankton bloom, indicating transient decoupling of bacterial production from metabolism. Ecological features such as this are readily detectable with the dual-label method.
通过将水样与氚标记的甲基胸腺嘧啶核苷和碳标记的氨基酸同时进行培养，可以估算水生系统中的细菌生产和氨基酸代谢。这种双标记方法不仅节省时间、人力和材料，还能在同一微生物亚群落中测定这两个参数。既可以估算有机碳的掺入量，也可以估算呼吸作用。在广泛的细菌活性范围内，双标记技术获得的结果与单放射性标记方法没有显著差异。该方法特别适用于大规模的野外项目，已成功应用于富营养化河口样本以及贫营养海洋水体。在切萨皮克湾的中盐度区域，胸腺嘧啶核苷掺入量的季节性变化范围为2至635皮摩尔·升⁻¹·小时⁻¹，氨基酸周转率的变化范围为0.01至28.4%·小时⁻¹。1985年在海湾中部一个深水站点对胸腺嘧啶核苷掺入量与氨基酸周转率测量结果的比较表明，一年中的大部分时间细菌生产与氨基酸代谢之间存在紧密耦合。然而，在春季浮游植物大量繁殖期间，深湾水域中特定生产的氨基酸周转率急剧增加，这表明细菌生产与代谢之间出现了短暂的解耦。使用双标记方法很容易检测到这样的生态特征。
