PNAS:与珊瑚有关的微生物群的宏基因组学
美国圣地亚哥州立大学的研究人员对珊瑚礁相关微生物群落的一个大尺度宏基因组学调查表明，这些微生物的分类学组成最多地受到了珊瑚和水藻等深海底大生物体的影响，而它们的代谢特化随着局部海洋学状况而变化。相关文章发表于2014年6月30日的《PNAS》杂志上。
微生物群落影响相关珊瑚礁的健康，但是支配微生物群落结构和基因流的机制在很大程度上仍然未知。
Linda Wegley Kelly及其同事对莱恩群岛的11个岛的22个中央太平洋珊瑚礁的珊瑚礁相关微生物的群落DNA进行了测序，这些岛屿有着大范围的生物地球化学和人类活动的影响。这组作者评估了3个变量之间的关系，这三个变量是珊瑚和水藻等深海底大生物体的覆盖百分比、营养级别以及纬度，还评估了在这些环状珊瑚岛的微生物群落的结构和代谢能力。
这组作者发现，在一个珊瑚礁出现的这些微生物分类单元以及它们的相对丰富程度反映了为它们提供初级局域能源的珊瑚和水藻群落。这些微生物的特异化以及生态相关代谢能力的存在与营养级别以及其他依赖于纬度的因素具有相关性。
根据这些发现，这组作者提出珊瑚礁相关微生物群落结构是由作为能量来源的珊瑚和水藻大生物体决定的，而当地的生物地球化学决定了精细尺度的代谢功能。
原文摘要：
Linda W. Kelly, Gareth J. Williams, Katie L. Barott, Craig A. Carlson, Elizabeth A. Dinsdale,Robert A. Edwards, Andreas F. Haas, Matthew Haynes, Yan Wei Lim, TrAcey McDole,Craig E. Nelson, Enric Sala, Stuart A. Sandin, Jennifer E. Smith, Mark J. A. Vermeij, Merry Youle andForest Rohwer
Holobionts are species-specific associations between macro- and microorganisms. On coral reefs, the benthic coverage of coral and algal holobionts varies due to natural and anthropogenic forcings. Different benthic macroorganisms are predicted to have specific microbiomes. In contrast, local environmental factors are predicted to select for specific metabolic pathways in microbes. To reconcile these two predictions, we hypothesized that adaptation of microbiomes to local conditions is facilitated by the horizontal transfer of genes responsible for specific metabolic capabilities. To test this hypothesis, microbial metagenomes were sequenced from 22 coral reefs at 11 Line Islands in the central Pacific that together span a wide range of biogeochemical and anthropogenic influences. Consistent with our hypothesis, the percent cover of major benthic functional groups significantly correlated with particular microbial taxa. Reefs with higher coral cover had a coral microbiome with higher abundances of Alphaproteobacteria (such as Rhodobacterales and Sphingomonadales), whereas microbiomes of algae-dominated reefs had higher abundances of Gammaproteobacteria (such as Alteromonadales, Pseudomonadales, and Vibrionales), Betaproteobacteria, and Bacteriodetes. In contrast to taxa, geography was the strongest predictor of microbial community metabolism. Microbial communities on reefs with higher nutrient availability (e.g., equatorial upwelling zones) were enriched in genes involved in nutrient-related metabolisms (e.g., nitrate and nitrite ammonification, Ton/Tol transport, etc.). On reefs further from the equator, microbes had more genes encoding chlorophyll biosynthesis and photosystems I/II. These results support the hypothesis that core microbiomes are determined by holobiont macroorganisms, and that those core taxa adapt to local conditions by selecting for advantageous metabolic genes.
作者：eurekalert
