Collaborative Research: EAGER: Salinity-based selection between sister clades of abundant coastal bacterioplankton

合作研究：EAGER：丰富的沿海浮游细菌姐妹进化枝之间基于盐度的选择

• 批准号: 1747722
• 负责人: Elizabeth Kujawinski
• 金额: $ 12.12万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1747722&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Salinity; based

Adaptation to new environments is a fundamental challenge for organisms, including microbes, in expanding their habitat range. It is important to investigate the cellular mechanisms underlying salinity tolerance in coastal bacterioplankton and their different responses to salinity in nature because (i) it will provide fundamental understanding for how microorganisms evolve to inhabit environments with different salinities, and (ii) alterations in coastal salinity are connected to climate change, so the way these alterations affect abundant coastal microorganisms also alters the biogeochemical cycling of, e.g., carbon. The project will examine microbial adaptations to salinity and determine how changes in salinity affect microbial metabolism using two closely related groups of abundant coastal bacterioplankton as model taxa. In addition, the research will continue and expand microbiology Course-based Undergraduate Research Experiences (mCUREs) in high-throughput cultivation and microbial characterization at the Lousiana State University. Sections of freshman biology laboratories will learn how to isolate, characterize, and molecularly identify microorganisms from local aquatic systems. mCURE sections will lead to newly isolated strains, genome sequences, and physiological data, these results will be published with the contributing students as co-authors. The relative success of mCURE sections will be assessed compared to traditional freshman biology sections. mCURE sections will offer unique opportunities for LSU students by creating excitement about research through discovery of new organisms and generating knowledge of the coastal habitats that are essential to the livelihood of the Gulf Coast.The evolutionary transition between salt- and freshwater environments occurs rarely in microorganisms. In one of the most abundant aquatic groups, SAR11, the transition between salt- and freshwater environments has happened only once: all freshwater SAR11 belong to subclade IIIb/LD12, which has also been found to inhabit coastal environments where salinity varies widely. The first reported isolates of the SAR11 freshwater clade LD12 and a member of the sister clade IIIa from the same region are now available. These pure culture representatives provide a powerful model for experimentally investigating adaptations to new environments in microorganisms, specifically (i) the genomic pathway and regulatory distinctions that arise during the evolutionary transition from marine to freshwater environments, and (ii) the physiological mechanisms that underlie the ecological restrictions imposed on microorganisms by ionic strength in coastal and freshwater environments. Furthermore, because these organisms have distinct differences in metabolic potential, the isolates facilitate testing (iii) the effects of changing coastal salinity on microbial contributions to other biogeochemical cycles, such as that for carbon. The project will test the hypothesis that the relative ionic strength tolerances between the sister lineages (LD12, IIIa) result from fundamental differences in metabolic flexibility at a genomic and regulatory level. To do so it will assess transcriptional and metabolic responses to varied ionic strength for both taxa and measure the distribution and activity of both groups in nature to translate laboratory findings to the field. The research will provide new understanding of LD12 habitat range and insights into how the "freshwater" lineage evolved from a SAR11 common ancestor. The project will also more generally provide important information on microbial responses to salinity changes in coastal systems and the evolutionary paths separating freshwater and marine microorganisms.This award is co-funded by Biological Oceanography, Division of Ocean Sciences in the Directorate for Geosciences and by Systems and Synthetic Biology, Division of Molecular and Cellular Biosciences in the Directorate for Biological Sciences.

对包括微生物在内的生物体来说，适应新环境是扩大其栖息地范围的根本挑战。研究沿海浮游细菌耐盐性的细胞机制及其对自然界盐度的不同反应具有重要意义，因为(I)这将为微生物如何进化以适应不同盐度的环境提供基本的理解，(Ii)海岸盐度的变化与气候变化有关，因此这些变化影响丰富的沿海微生物的方式也改变了生物地球化学循环，例如碳。该项目将研究微生物对盐度的适应，并确定盐度的变化如何影响微生物的新陈代谢，使用两组密切相关的丰富的沿海浮游细菌作为模式类群。此外，这项研究将继续并扩大路易斯安那州立大学在高通量培养和微生物特性方面基于微生物学课程的本科生研究经验(MCURE)。新生生物实验室的各个部分将学习如何从当地的水生系统中分离、鉴定和分子鉴定微生物。MCURE部分将导致新分离的菌株、基因组序列和生理数据，这些结果将与贡献的学生作为共同作者发表。MCURE部分的相对成功程度将与传统的新生生物部分进行比较。MCURE部分将为路易斯安那州立大学的学生提供独特的机会，通过发现新生物来激发对研究的兴奋，并产生对墨西哥湾沿岸的生计至关重要的沿海栖息地的知识。海水和淡水环境之间的进化转变在微生物中很少发生。在资源最丰富的水生类之一SAR11中，咸水环境和淡水环境之间的转变只发生过一次：所有淡水SAR11都属于IIIb/LD12亚纲，也被发现生活在盐度变化很大的沿海环境中。来自同一地区的SAR11淡水支系LD12和姊妹支系IIIa的第一批分离株现已问世。这些纯培养代表为实验研究微生物对新环境的适应提供了一个强大的模型，特别是(I)在从海洋环境到淡水环境的进化转变过程中出现的基因组途径和调控差异，以及(Ii)沿海和淡水环境中离子强度对微生物施加生态限制的生理机制。此外，由于这些生物在代谢潜力上有明显的差异，这些分离株有助于测试(Iii)沿海盐度变化对微生物对其他生物地球化学循环的影响，例如对碳的影响。该项目将检验这一假设，即姐妹谱系(LD12，IIIa)之间的相对离子强度耐受性是由于基因组和调控水平上代谢灵活性的根本差异造成的。为此，它将评估两个分类群对不同离子强度的转录和代谢反应，并测量两个类群在自然界中的分布和活性，以将实验室发现转化为实地研究。这项研究将提供对LD12栖息地范围的新理解，并深入了解“淡水”世系是如何从SAR11共同祖先进化而来的。该项目还将更广泛地提供关于微生物对沿海系统盐度变化的反应以及淡水和海洋微生物之间的进化路径的重要信息。该奖项由地球科学局海洋科学部生物海洋学和生物科学局分子和细胞生物科学部系统和合成生物学共同资助。