Small Scale Spatial and Temporal Variations in Bacterial Activity in Marine Waters

海水中细菌活动的小尺度时空变化

• 批准号: 9986331
• 负责人: Michael Sieracki
• 金额: $ 33.01万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 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: 2000-05-01 至 2003-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9986331&HistoricalAwards=false
• 关键词: Small; Scale; Spatial; Temporal; Variations

Bacteria in the ocean play a key role in transforming dissolved organic matter into C02 through respiration and into biomass that is available to higher trophic levels within the microbial food web. They are the dominant form of biomass in the ocean. From highly productive coastal and upwelling regions to extremely oligotrophic waters, bacteria abundances range only between about 10 to 10 ml, respectively. The activity of these bacteria, however, varies much more widely. Typically examined spatial scales of meters to kilometers may not be appropriate for cells that are smaller than 10-6 in and may occur in patches on the scale of 10-5 to 10-3 M. Microscale patchiness can provide concentrations of organic nutrients to cells much higher than those measured by bulk methods, leading to very different predictions of bacterial responses to physical and biogeochemical perturbations. In this project we propose to use automated flow and imaging cytometry combined with sensitive -fluorescence methods to measure the single-cell composition and activity of marine bacteria at small spatial and diel temporal scales. A variety of single-cell fluorescent probes will be used to indicate cell composition such as protein and nucleic acid content, and physiological processes such as respiration, membrane potential, and enzyme activity. These single-cell responses will be quantified using automated flow and imaging cytometric methods for increased sensitivity and count precision, quantitative fluorescence per cell measurement, and objective detection - all improvements over visual microscope methods. Our laboratory is uniquely equipped and experienced in these approaches. Bulk and single- cell methods will be compared. Microscale patchiness of bacterial activity (as ell as abundance) will be examined over a range of spatial scales and natural turbulent mixing conditions. The size distributions of active and total bacterial populations will be measured over seasonal cycles and across trophic gradients providing a variety of regimes of plankton community structure. Short time variations in bacterial activity will also be studied to determine how bacterial activity varies over diel cycles. Experiments will be conducted over seasonal time scales and on cruises from productive, coastal waters to oligotrophic, blue water sites. By measuring single-cell activities at appropriately small spatial and short temporal scales, but across the dominant ecological gradients of the temperate ocean we will gain significant insight into the mechanisms controlling bacterial biogeochemical processes.

海洋中的细菌在通过呼吸将溶解的有机物转化为CO 2 以及微生物食物网内较高营养级可利用的生物质方面发挥着关键作用。它们是海洋中生物量的主要形式。从高生产力的沿海和上升流区域到极度贫营养的水域，细菌丰度范围分别仅为约 10 至 10 毫升。然而，这些细菌的活性差异很大。通常检查的米到公里的空间尺度可能不适合小于 10-6 英寸的细胞，并且可能出现在 10-5 到 10-3 M 尺度的斑块中。微尺度斑块可以为细胞提供比批量方法测量的浓度高得多的有机营养物浓度，从而导致细菌对物理和生物地球化学扰动的反应的预测非常不同。在这个项目中，我们建议使用自动流式细胞术和成像细胞术与敏感荧光方法相结合，在小空间和昼夜尺度上测量海洋细菌的单细胞组成和活性。各种单细胞荧光探针将用于指示细胞组成（例如蛋白质和核酸含量）以及生理过程（例如呼吸、膜电位和酶活性）。这些单细胞反应将使用自动流式细胞术和成像细胞计数方法进行量化，以提高灵敏度和计数精度、每个细胞的定量荧光测量和客观检测——所有这些都比视觉显微镜方法有所改进。我们的实验室在这些方法方面拥有独特的装备和经验。将比较批量方法和单细胞方法。将在一系列空间尺度和自然湍流混合条件下检查细菌活性（以及丰度）的微观斑块。将在季节周期和营养梯度上测量活性细菌种群和总细菌种群的大小分布，从而提供浮游生物群落结构的各种制度。还将研究细菌活性的短时变化，以确定细菌活性在昼夜循环中如何变化。实验将在季节性时间范围内进行，并在从生产性沿海水域到贫营养性蓝色水域的巡航中进行。通过在适当的小空间和短时间尺度上测量单细胞活动，但跨越温带海洋的主要生态梯度，我们将深入了解控制细菌生物地球化学过程的机制。