Underway Mapping of Alkaline Phosphatase Activity in the Mississippi River Plume: Real-Time Evidence for Phosphorus Limitation

正在进行密西西比河羽流中碱性磷酸酶活性的测绘：磷限制的实时证据

• 批准号: 9911865
• 负责人: James Ammerman
• 金额: $ 21.07万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9911865&HistoricalAwards=false
• 关键词: Underway; Mapping; Alkaline; Phosphatase; Activity

Microbial ectoenzyme activities in aquatic environments are important agents of polymer hydrolysis and indicators of the state of microbial carbon, nitrogen, or phosphorus nutrition. Alkaline phosphatase, in particular, is a good indicator of phosphorus limitation. However, like most other biochemical and molecular measurements, ectoenzyme activities, including alkaline phosphatase, have been limited to discreet water samples. We have developed a continuous underway method for measuring alkaline phosphatase and other microbial enzyme activities using high-sensitivity fluorescent substrates. This method has been successfully employed to map surface alkaline phosphatase activity in a limited area of the Mississippi River plume and the Louisiana shelf, the area where phosphorus limitation is likely to be most intense. This proposed study will use an improved automated enzyme measurement system for extensive seasonal mapping of surface water alkaline phosphatase activity in the Mississippi plume and along the Louisiana coast. This system will be coupled with continuous underway measurements of temperature, salinity, in vivo fluorescence and other parameters provided by the ship. This work will be conducted in conjunction with a previously-funded comprehensive process study of nitrogen, phosphorus, and silica limitation in this area to be conducted by Quay Dortch and David Nelson. The seasonal alkaline phosphatase mapping will provide importantinformation on the spatial and temporal extent of phosphorus limitation, which will aid in the selection of stations for detailed nutrient enrichment experiments by Dortch and Nelson. These nutrient enrichment experiments, in turn, will supply detailed information on the response of the community to nutrient enrichment, which will help in the interpretation of the mapping data. Additional alkaline phosphatase measurements will be made on samples from the nutrient enrichment experiments to help in the interpretation of their physiological status.

水生环境中微生物外酶活性是聚合物水解的重要因子，也是微生物碳、氮、磷营养状态的指示物。特别是碱性磷酸酶，是一个很好的磷限制指标。然而，像大多数其他生化和分子测量一样，包括碱性磷酸酶在内的外酶活性仅限于谨慎的水样。我们已经开发了一种连续进行的方法来测量碱性磷酸酶和其他微生物酶的活性使用高灵敏度荧光底物。该方法已被成功地用于绘制密西西比河羽流和路易斯安那大陆架有限区域的表面碱性磷酸酶活性图，该区域的磷限制可能最为强烈。这项拟议的研究将使用一种改进的自动化酶测量系统，对密西西比河羽流和路易斯安那州海岸的地表水碱性磷酸酶活性进行广泛的季节性测绘。该系统将与船舶提供的温度、盐度、体内荧光和其他参数的连续航行测量相结合。这项工作将与Quay Dortch和David Nelson之前资助的一项关于该地区氮、磷和二氧化硅限制的综合工艺研究结合起来进行。季节性碱性磷酸酶图谱将提供有关磷限制的时空范围的重要信息，这将有助于Dortch和Nelson选择进行详细营养富集实验的站点。这些营养物富集实验反过来将提供有关群落对营养物富集反应的详细信息，这将有助于对制图数据的解释。额外的碱性磷酸酶测量将从营养富集实验的样品，以帮助解释他们的生理状态。