Activity and Characteristics of the Dissolved Organic Carbon-Dependent Picoplankton over the Annual Cycle in a Subarctic Lake

亚北极湖泊溶解有机碳依赖的超微型浮游生物年周期的活动和特征

• 批准号: 0243913
• 负责人: Don Button
• 金额: $ 30万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2005-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0243913&HistoricalAwards=false
• 关键词: Activity; Characteristics; Dissolved; Organic; Carbon

ABSTRACT ButtonOPP-0243913The Principal Investigator will make in situ measurements made throughout the annual cycle in a near arctic lake where photosynthesis rates vary from zero to 500 mg C/m2 per day due to large changes in sun angle and snow cover. The work will focus on changes in the bacterioplankton over the winter/summer transition. Bacterial activity will be determined by substrate uptake, usually an amino acid mixture. Measurements will include artificial warming and cooling to determine activation energies from which temperature preferences are evaluated. Incubations will include an auxiliary substrate such as glucose to help determine the energization state of organisms in the collected sample. These activation energies are determined in conjunction with membrane potential measurements of the individual cells by flow cytometry. Companion measurements will be cell population and mass by flow cytometry for calculating specific affinities. The distribution of cell mass and DNA/cell is used as a further index of organism activity over the seasons. Cell yields from substrate consumed over the seasons will be used to help determine productivity and endogenous requirements, particularly during winter. These are linked to dissolved free amino acid concentrations as an indication of labile organic substrates. Further characterization will be by DNA fragment and sequence analyses. Existing culture collections of isolates will be further developed with the objective of finding and characterizing a typical low DNA, small, typical freshwater oligobacterium for physiological study. Cultures are used to determine values for missing terms in specific affinity theory such as the size of thresholds for substrate uptake and the concentration of transported substrate in cytoplasmic pools. Expanded statistical theory for testing cell-cell interactions will be applied with the objective of improving the small (1%) culturability presently attained. This work involves the application of novel theory and methods to the understanding of microbial processes in the Arctic with particular reference to seasonal changes in water temperature. These will serve to improve estimates of bacterial activity and productivity. Novel extinction culture procedures coupled with new statistical and kinetic theory can help solidify the sparse understanding of one of our largest forms of active living material. Developing kinetic theory is beginning to alter paradigms, as is quantitative flow cytometry together with nutrient flux calculations, and is thereby altering perceptions of oligobacterial physiology. The novel technology will be extended to a wide cross section of students through graduate and undergraduate courses and seminars. The broader impacts of the work include the development of novel concepts, such as ways of linking aspects of the carbon and nutrient cycle to organism activity, physiology, nutrient concentrations, and temperature. Developments in component technologies, such as quantitative flow cytometry and extinction culturing, are applicable to microbiology in general. Most importantly the work will provide a mechanistically competent alternative to the Michaelis Menten paradigm to improve description and comparison of microbial activity and dynamics.

主要研究者将在一个近北极的湖泊中进行全年的原位测量，由于太阳角度和积雪的巨大变化，该湖泊的光合作用速率从每天0到500 mg C/m2不等。这项工作将集中在冬季/夏季过渡期间浮游细菌的变化。细菌活性将通过底物摄取来确定，通常是氨基酸混合物。测量将包括人工加热和冷却，以确定活化能，从中评估温度偏好。孵育将包括辅助底物，如葡萄糖，以帮助确定所采集样本中微生物的微生物状态。通过流式细胞术结合单个细胞的膜电位测量来确定这些活化能。伴随测量将是通过流式细胞术的细胞群和质量，用于计算特异性亲和力。细胞质量和DNA/细胞的分布被用作生物体在季节中活动的进一步指标。细胞产量从基板消耗的季节将被用来帮助确定生产力和内源性需求，特别是在冬季。这些与溶解的游离氨基酸浓度相关，作为不稳定有机底物的指示。将通过DNA片段和序列分析进行进一步表征。将进一步开发现有的分离株培养物，目的是发现和表征典型的低DNA、小的、典型的淡水寡杆菌，用于生理学研究。培养物用于确定特异性亲和力理论中缺失项的值，例如底物摄取阈值的大小和细胞质池中转运底物的浓度。将应用扩展的统计理论来测试细胞-细胞相互作用，目的是提高目前达到的小（1%）可培养性。这项工作涉及应用新的理论和方法来了解北极的微生物过程，特别是水温的季节性变化。这些将有助于改善对细菌活性和生产力的估计。新的灭绝文化程序加上新的统计和动力学理论可以帮助巩固我们最大形式的活性生物材料之一的稀疏理解。发展动力学理论开始改变范式，因为是定量流式细胞术与营养通量计算，从而改变了寡细菌生理学的看法。这项新技术将通过研究生和本科生课程以及研讨会扩展到广泛的学生群体。这项工作的更广泛影响包括新概念的发展，例如将碳和营养循环的各个方面与生物体活动，生理学，营养浓度和温度联系起来的方法。组件技术的发展，如定量流式细胞术和灭绝培养，适用于一般的微生物学。最重要的是，这项工作将提供一个机械上胜任的替代米氏范式，以改善微生物活性和动力学的描述和比较。