Collaborative Research: Dimensions: The Macroalgal Microbiome in Space and Time---Maintaining Primary Producers in the Atlantic Rocky Intertidal Zone

潮间带大型藻类（“海藻”）为许多无脊椎动物和幼鱼提供栖息地、庇护所和食物。人们对潮间带藻类如何应对自然压力了解甚多，但对与这些藻类相关的自然细菌群落知之甚少。过去在实验室的研究发现，一些“海藻”在被抗生素去除细菌后会分解，这表明这些细菌对其宿主的健康至关重要。这项研究将研究与几种“海藻”相关的细菌生物多样性的遗传、分类和功能方面，这些“海藻”对海洋生态系统的总体健康特别重要。这项研究将确定这些细菌如何随着季节、潮间带的位置和纬度范围而变化。通过研究在不同采样时间存在的特定细菌基因和研究宿主对接种特定细菌的反应，将检查与宿主相关的细菌种类的稳定性或变化。这项工作还将研究在潮间带或纬度上发现的极端环境是否会抑制任何细菌，特别是在宿主活动范围的南部边界，那里的气候变化可能会扰乱宿主身上的细菌群落。研究人员将把分离物和代金券标本存入公共收藏，并与训练有素的公民科学家合作，将提供缅因大学植物标本室内所有藻类材料的数字访问。在这项研究中收集的多方面的数据将有助于其他潮间带生态学家的研究。大藻微生物群在空间和时间上是如何变化的，我们知之甚少。大藻微生物群是“冷、湿”还是“热、干”？如果有，这对宿主功能有何影响？在这里，微生物组将在缅因州海岸的潮间带的垂直梯度上被区分为两个突出的属，Fucus （rockweed）和Porphyra（紫菜）。与此同时，一项对中带Porphyra umbilicalis和Fucus vesiculosus微生物组的跨大西洋研究将确定在潮间带应力梯度上发现的成分变化是否反映在中带物种的纬度范围上。如果有，这有关系吗？这个问题将通过使用散弹枪宏基因组分析来比较遗传组成与大藻微生物组的特征分类组成来回答。与微生物组收集相关的环境变化将通过现场传感器和政府气候服务（如NOAA）提供的档案和实时数据进行测量。利用植物标本室标本评估在历史时期检测变化的潜力。为了研究可能对Fucus和porphya的正常结构和功能最关键的细菌，研究人员将重点研究从孢子和受精卵中分离出的细菌，借助流式细胞术和单细胞基因组学。为了确定这些关联的重要性，将用这些细菌分离物接种微生物组耗尽的胚胎，并通过RNA-Seq分析宿主转录组来研究由此产生的相互作用。关键细菌种类（操作分类单位）的耐温性将在实验室实验中建立。这项研究将为大藻微生物群落的生物多样性提供一个重要的跨大西洋基线。

Intertidal macro algae ('seaweeds') provide habitat, shelter and food to many invertebrates and young fishes. Much is known about how intertidal algae react to natural stresses, but little is known about the natural community of bacteria associated with these algae. Past studies in the laboratory found that some 'seaweeds' disintegrate after removal of their bacteria with antibiotics suggesting these bacteria are essential to the health of their hosts. This research will examine the genetic, taxonomic, and functional aspects of biodiversity of bacteria associated with several 'seaweeds' that are particularly important to the general health of marine ecosystems. The research will determine how these bacteria change with season, position within the intertidal zone and latitudinal range. Stability or change in the bacterial species associated with a host will be examined by studying the particular bacterial genes that are present at different sampling times and by studying host responses to inoculations with particular bacteria. The work will also study whether any bacteria are inhibited by the environmental extremes found across the intertidal zone or over latitude, especially at the southern borders of a host's range where climate change may disturb the bacterial community on the host. Researchers will deposit isolates and voucher specimens into public collections, and, in collaboration with trained citizen scientists, will provide digital access to all algal materials within the University of Maine Herbarium. The multi-faceted data collected during this research will aid studies by other intertidal ecologists. How macroalgal microbiomes change in space and time is poorly known. Is there a 'cool, wet' versus a 'hot, dry' macroalgal microbiome(s)? If so, how does this affect host function? Here, microbiomes will be characterized over the vertical gradient of the intertidal zone on the Maine shore in differentially zoned species within each of two prominent genera, Fucus (rockweed) and Porphyra (laver). Contemporaneously, a trans-Atlantic study of microbiomes of the mid-zone Porphyra umbilicalis and Fucus vesiculosus will determine whether compositional changes found over an intertidal stress gradient are mirrored over the latitudinal range of mid-zoned species. If so, does this matter? This question will be answered by using shotgun metagenomic analyses to compare the genetic composition with the characterized taxonomic composition of the macroalgal microbiomes. Environmental variation associated with microbiome collections will be measured with in situ sensors and from archival and real time data available from government climate services (e.g., NOAA). The potential to detect changes over historic time will be assessed using herbarium specimens. To study bacteria that are likely to be most critical to normal structure and function of Fucus and Porphyra, the researchers will focus on bacterial isolations from spores and fertilized eggs, aided by flow cytometry and single cell genomics. To establish the criticality of these associations, microbiome-depleted embryos will be inoculated with such bacterial isolates, and the resulting interaction will be investigated by analysis of the host transcriptome with RNA-Seq. The temperature tolerance of key bacterial species (operational taxonomic units) will be established in laboratory experiments. This research will serve as an important trans-Atlantic baseline of the biodiversity of macroalgal microbiomes.