Brown Tanya, Otero Christopher, Grajales Alejandro, Rodriguez Estefania, Rodriguez-Lanetty Mauricio
Biological Sciences, Florida International University, Miami, FL, USA.
Invertebrate Zoology, American Museum of Natural History, New York, NY, USA.
PeerJ. 2017 May 16;5:e3235. doi: 10.7717/peerj.3235. eCollection 2017.
Examination of host-microbe interactions in early diverging metazoans, such as cnidarians, is of great interest from an evolutionary perspective to understand how host-microbial consortia have evolved. To address this problem, we analyzed whether the bacterial community associated with the cosmopolitan and model sea anemone shows specific patterns across worldwide populations ranging from the Caribbean Sea, and the Atlantic and Pacific oceans. By comparing sequences of the V1-V3 hypervariable regions of the bacterial 16S rRNA gene, we revealed that anemones host a complex and diverse microbial community. When examined at the phylum level, bacterial diversity and abundance associated with are broadly conserved across geographic space with samples, containing largely and However, the species-level makeup within these phyla differs drastically across space suggesting a high-level core microbiome with local adaptation of the constituents. Indeed, no bacterial OTU was ubiquitously found in all anemones samples. We also revealed changes in the microbial community structure after rearing anemone specimens in captivity within a period of four months. Furthermore, the variation in bacterial community assemblages across geographical locations did not correlate with the composition of microalgal symbionts. Our findings contrast with the postulation that cnidarian hosts might actively select and maintain species-specific microbial communities that could have resulted from an intimate co-evolution process. The fact that is likely an introduced species in most sampled localities suggests that this microbial turnover is a relatively rapid process. Our findings suggest that environmental settings, not host specificity, seem to dictate bacterial community structure associated with this sea anemone. More than maintaining a specific composition of bacterial species some cnidarians associate with a wide range of bacterial species as long as they provide the same physiological benefits towards the maintenance of a healthy host. The examination of the previously uncharacterized bacterial community associated with the cnidarian sea anemone model is the first global-scale study of its kind.
从进化的角度来看，研究早期分化的后生动物（如刺胞动物）中的宿主 - 微生物相互作用，对于理解宿主 - 微生物共生体如何进化具有重要意义。为了解决这个问题，我们分析了与分布广泛的模式海葵相关的细菌群落，是否在从加勒比海、大西洋到太平洋的全球种群中呈现出特定模式。通过比较细菌16S rRNA基因V1 - V3高变区的序列，我们发现海葵宿主着一个复杂多样的微生物群落。在门水平上进行检查时，与海葵相关的细菌多样性和丰度在地理空间上的样本中大致保守，样本中主要包含变形菌门和拟杆菌门。然而，这些门内的物种水平组成在不同空间中差异很大，这表明存在一个高水平的核心微生物组，其组成部分具有局部适应性。事实上，在所有海葵样本中并未普遍发现相同的细菌操作分类单元（OTU）。我们还揭示了在圈养环境中饲养海葵标本四个月后微生物群落结构的变化。此外，不同地理位置的细菌群落组合变化与微藻共生体的组成无关。我们的研究结果与刺胞动物宿主可能会积极选择并维持由紧密共同进化过程产生的物种特异性微生物群落这一假设形成对比。在大多数采样地点，海葵可能是外来物种这一事实表明，这种微生物更替是一个相对快速的过程。我们的研究结果表明，环境因素而非宿主特异性似乎决定了与这种海葵相关的细菌群落结构。一些刺胞动物并非维持特定的细菌物种组成，而是只要这些细菌对维持健康宿主提供相同的生理益处，就会与广泛的细菌物种相关联。对与刺胞动物海葵模式相关的此前未被表征的细菌群落的研究，是此类首次全球规模的研究。
