Lee Michael D, Webb Eric A, Walworth Nathan G, Fu Fei-Xue, Held Noelle A, Saito Mak A, Hutchins David A
Marine Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institute, Woods Hole, Massachusetts, USA.
Appl Environ Microbiol. 2017 Dec 15;84(1). doi: 10.1128/AEM.02026-17. Print 2018 Jan 1.
is a globally distributed cyanobacterium whose nitrogen-fixing capability fuels primary production in warm oligotrophic oceans. Like many photoautotrophs, serves as a host to various other microorganisms, yet little is known about how this associated community modulates fluxes of environmentally relevant chemical species into and out of the supraorganismal structure. Here, we utilized metatranscriptomics to examine gene expression activities of microbial communities associated with (strain IMS101) using laboratory-maintained enrichment cultures that have previously been shown to harbor microbial communities similar to those of natural populations. In enrichments maintained under two distinct CO concentrations for ∼8 years, the community transcriptional profiles were found to be specific to the treatment, demonstrating a restructuring of overall gene expression had occurred. Some of this restructuring involved significant increases in community respiration-related transcripts under elevated CO, potentially facilitating the corresponding measured increases in host nitrogen fixation rates. Particularly of note, in both treatments, community transcripts involved in the reduction of nitrate, nitrite, and nitrous oxide were detected, suggesting the associated organisms may play a role in colony-level nitrogen cycling. Lastly, a taxon-specific analysis revealed distinct ecological niches of consistently cooccurring major taxa that may enable, or even encourage, the stable cohabitation of a diverse community within consortia. is a genus of globally distributed, nitrogen-fixing marine cyanobacteria. As a source of new nitrogen in otherwise nitrogen-deficient systems, these organisms help fuel carbon fixation carried out by other more abundant photoautotrophs and thereby have significant roles in global nitrogen and carbon cycling. Members of the genus tend to form large macroscopic colonies that appear to perpetually host an association of diverse interacting microbes distinct from the surrounding seawater, potentially making the entire assemblage a unique miniature ecosystem. Since its first successful cultivation in the early 1990s, there have been questions about the potential interdependencies between and its associated microbial community and whether the host's seemingly enigmatic nitrogen fixation schema somehow involved or benefited from its epibionts. Here, we revisit these old questions with new technology and investigate gene expression activities of microbial communities living in association with .
是一种全球分布的蓝细菌，其固氮能力为温暖的贫营养海洋中的初级生产提供了动力。与许多光合自养生物一样，它是各种其他微生物的宿主，但对于这个相关群落如何调节环境相关化学物质进出超生物体结构的通量，人们知之甚少。在这里，我们利用宏转录组学来研究与（菌株IMS101）相关的微生物群落的基因表达活动，使用的是实验室维持的富集培养物，这些培养物此前已被证明含有与自然种群相似的微生物群落。在两种不同CO浓度下维持约8年的富集培养物中，发现群落转录谱具有处理特异性，表明整体基因表达发生了重组。这种重组的一些情况涉及在高CO浓度下与群落呼吸相关的转录本显著增加，这可能促进了相应测量到的宿主固氮率的增加。特别值得注意的是，在两种处理中，都检测到了与硝酸盐、亚硝酸盐和一氧化二氮还原相关的群落转录本，这表明相关生物可能在群体水平的氮循环中发挥作用。最后，一项分类群特异性分析揭示了始终共同出现的主要分类群的不同生态位，这可能使或甚至促进了不同群落稳定地共存于聚球藻聚集体中。聚球藻属是一类全球分布的固氮海洋蓝细菌。作为原本缺氮系统中的新氮源，这些生物有助于为其他更丰富的光合自养生物进行的碳固定提供动力，从而在全球氮和碳循环中发挥重要作用。聚球藻属成员倾向于形成大型宏观聚集体，这些聚集体似乎永久地承载着与周围海水不同的多种相互作用微生物的关联，这可能使整个组合成为一个独特的微型生态系统。自20世纪90年代初首次成功培养以来，一直存在关于聚球藻与其相关微生物群落之间潜在相互依存关系的问题，以及宿主看似神秘的固氮模式是否以某种方式涉及或受益于其体表共生生物。在这里，我们用新技术重新审视这些老问题，并研究与聚球藻相关的微生物群落的基因表达活动。
