Aquatic Research Facility, Environmental Sustainability Research Centre, University of Derby, Derby, UK.
Marine Laboratory, University of Guam, Mangilao, GU, 96923, Guam.
Microbiome. 2019 Nov 22;7(1):139. doi: 10.1186/s40168-019-0759-6.
Coral reefs face unprecedented declines in diversity and cover, a development largely attributed to climate change-induced bleaching and subsequent disease outbreaks. Coral-associated microbiomes may strongly influence the fitness of their hosts and alter heat tolerance and disease susceptibility of coral colonies. Here, we describe a new coral disease found in Micronesia and present a detailed assessment of infection-driven changes in the coral microbiome.
Combining field monitoring and histological, microscopic and next-generation barcoding assessments, we demonstrate that the outbreak of the disease, named 'grey-patch disease', is associated with the establishment of cyanobacterial biofilm overgrowing coral tissue. The disease is characterised by slow progression rates, with coral tissue sometimes growing back over the GPD biofilm. Network analysis of the corals' microbiome highlighted the clustering of specific microbes which appeared to benefit from the onset of disease, resulting in the formation of 'infection clusters' in the microbiomes of apparently healthy corals.
Our results appear to be in contrast to the recently proposed Anna-Karenina principle, which states that disturbances (such as disease) trigger chaotic dynamics in microbial communities and increase β-diversity. Here, we show significantly higher community similarity (compositional homogeneity) in the pathobiome of diseased corals, compared to the microbiome associated with apparently healthy tissue. A possible explanation for this pattern is strong competition between the pathogenic community and those associated with the 'healthy' coral holobiont, homogenising the composition of the pathobiome. Further, one of our key findings is that multiple agents appear to be involved in degrading the corals' defences causing the onset of this disease. This supports recent findings indicating a need for a shift from the one-pathogen-one-disease paradigm to exploring the importance of multiple pathogenic players in any given disease.
珊瑚礁的多样性和覆盖率正以前所未有的速度下降，这一发展在很大程度上归因于气候变化引起的白化现象以及随后的疾病爆发。珊瑚相关的微生物组可能会强烈影响宿主的适应性，并改变珊瑚虫的耐热性和疾病易感性。在这里，我们描述了一种在密克罗尼西亚发现的新珊瑚疾病，并对感染驱动的珊瑚微生物组变化进行了详细评估。
通过现场监测和组织学、显微镜和下一代条形码评估相结合，我们证明了这种名为“灰斑病”的疾病爆发与蓝细菌生物膜在珊瑚组织上过度生长有关。这种疾病的进展速度较慢，珊瑚组织有时会在 GPD 生物膜上重新生长。珊瑚微生物组的网络分析突出了特定微生物的聚类，这些微生物似乎受益于疾病的发生，导致在看似健康的珊瑚的微生物组中形成“感染簇”。
我们的研究结果似乎与最近提出的安娜·卡列尼娜原则相矛盾，该原则指出，干扰（如疾病）会引发微生物群落的混沌动力学，增加β多样性。在这里，我们发现与明显健康组织相关的微生物组相比，患病珊瑚的pathobiome 具有更高的群落相似性（组成同质性）。这种模式的一个可能解释是，致病群落与那些与“健康”珊瑚整体共生体相关的群落之间存在强烈竞争，使pathobiome 的组成同质化。此外，我们的一个关键发现是，似乎有多种因子参与了削弱珊瑚防御能力的过程，导致了这种疾病的发生。这支持了最近的研究结果，即需要从一种病原体一种疾病的范式转变为探索在任何给定疾病中多种致病因子的重要性。
