Apprill Amy, Marlow Heather Q, Martindale Mark Q, Rappé Michael S
Hawaii Institute of Marine Biology, SOEST, University of Hawaii, Kaneohe, HI, USA.
ISME J. 2009 Jun;3(6):685-99. doi: 10.1038/ismej.2009.3. Epub 2009 Feb 26.
Associations between healthy adult reef-building corals and bacteria and archaea have been observed in many coral species, but the initiation of their association is not understood. We investigated the onset of association between microorganisms and Pocillopora meandrina, a coral that vertically seeds its eggs with symbiotic dinoflagellates before spawning. We compared the bacterial communities associated with prespawned oocyte bundles, spawned eggs, and week old planulae using multivariate analyses of terminal restriction fragment length polymorphisms of SSU rRNA genes, which revealed that the composition of bacteria differed between these life stages. Additionally, planulae raised in ambient seawater and seawater filtered to reduce the microbial cell density harbored dissimilar bacterial communities, though SSU rRNA gene clone libraries showed that planulae raised in both treatments were primarily associated with different members of the Roseobacter clade of Alphaproteobacteria. Fluorescent in situ hybridization with an oligonucleotide probe suite targeting all bacteria and one oligonucleotide probe targeting members of the Roseobacter clade was used to localize the bacterial cells. Only planulae greater than 3 days old were observed to contain internalized bacterial cells, and members of the Roseobacter clade were detected in high abundance within planula tissues exposed to the ambient seawater treatment. We conclude that the onset of association between microorganisms and the coral P. meandrina appears to occur through horizontal uptake by planulae older than 79 h, and that uptake is preferential to members of the Roseobacter clade and potentially sensitive to the ambient seawater microbial community.
在许多珊瑚物种中都观察到了健康的成年造礁珊瑚与细菌和古菌之间的关联，但它们这种关联的起始过程尚不清楚。我们研究了微生物与丛生盔形珊瑚（Pocillopora meandrina）之间关联的起始情况，丛生盔形珊瑚在产卵前会将共生双鞭毛虫垂直植入其卵中。我们使用SSU rRNA基因末端限制性片段长度多态性的多变量分析，比较了与产卵前的卵母细胞束、产出的卵以及一周大的浮浪幼虫相关的细菌群落，结果显示这些生命阶段的细菌组成有所不同。此外，在环境海水和经过过滤以降低微生物细胞密度的海水中培养的浮浪幼虫拥有不同的细菌群落，不过SSU rRNA基因克隆文库表明，在这两种处理方式下培养的浮浪幼虫主要与α-变形菌纲红杆菌属（Roseobacter clade）的不同成员相关联。使用针对所有细菌的一组寡核苷酸探针和针对红杆菌属成员的一个寡核苷酸探针进行荧光原位杂交，以定位细菌细胞。仅观察到3天以上的浮浪幼虫含有内化的细菌细胞，并且在暴露于环境海水处理的浮浪幼虫组织中大量检测到红杆菌属的成员。我们得出结论，微生物与丛生盔形珊瑚之间关联的起始似乎是通过79小时以上的浮浪幼虫水平摄取发生的，并且这种摄取优先针对红杆菌属的成员，并且可能对环境海水微生物群落敏感。
