Damjanovic Katarina, van Oppen Madeleine J H, Menéndez Patricia, Blackall Linda L
School of BioSciences, The University of Melbourne, Parkville, VIC, Australia.
Australian Institute of Marine Science, Townsville, QLD, Australia.
Front Microbiol. 2019 Jul 24;10:1702. doi: 10.3389/fmicb.2019.01702. eCollection 2019.
Coral-associated microorganisms are essential for maintaining the health of the coral holobiont by participating in nutrient cycling and protecting the coral host from pathogens. Under stressful conditions, disruption of the coral prokaryotic microbiome is linked to increased susceptibility to diseases and mortality. Inoculation of corals with beneficial microbes could confer enhanced stress tolerance to the host and may be a powerful tool to help corals thrive under challenging environmental conditions. Here, we explored the feasibility of coral early life stage microbiome manipulation by repeatedly inoculating coral recruits with a bacterial cocktail generated in the laboratory. Co-culturing the two species and allowed us to simultaneously investigate the effect of host factors on the coral microbiome. Inoculation cocktails were regularly prepared from freshly grown pure bacterial cultures, which were hence assumed viable, and characterized via the optical density measurement of each individual strain put in suspension. Coral early recruits were inoculated seven times over 3 weeks and sampled once 36 h following the last inoculation event. At this time point, the cumulative inoculations with the bacterial cocktails had a strong effect on the bacterial community composition in recruits of both coral species. While the location of bacterial cells within the coral hosts was not assessed, metabarcoding using the 16S rRNA gene revealed that two and six of the seven bacterial strains administered through the cocktails were significantly enriched in inoculated recruits of and , respectively, compared to control recruits. Despite being reared in the same environment, and established significantly different bacterial communities, both in terms of taxonomic composition and diversity measurements. These findings indicate that coral host factors as well as the environmental bacterial pool play a role in shaping coral-associated bacterial community composition. Host factors may include microbe transmission mode (horizontal versus maternal) and host specificity. While the long-term stability of taxa included in the bacterial inocula as members of the host-associated microbiome remains to be evaluated, our results provide support for the feasibility of coral microbiome manipulation, at least in a laboratory setting.
珊瑚相关微生物对于维持珊瑚共生体的健康至关重要，它们通过参与营养循环以及保护珊瑚宿主免受病原体侵害来实现这一点。在压力条件下，珊瑚原核微生物群落的破坏与疾病易感性增加和死亡率上升有关。用有益微生物接种珊瑚可以赋予宿主更强的胁迫耐受性，并且可能是帮助珊瑚在具有挑战性的环境条件下茁壮成长的有力工具。在此，我们通过用实验室产生的细菌混合物反复接种珊瑚幼体，探索了操纵珊瑚幼体早期微生物组的可行性。将这两个物种共同培养使我们能够同时研究宿主因素对珊瑚微生物组的影响。接种混合物定期由新生长的纯细菌培养物制备，因此假定其具有活力，并通过对悬浮液中每个菌株的光密度测量进行表征。珊瑚幼体在3周内接种7次，并在最后一次接种事件后36小时取样一次。在这个时间点，用细菌混合物进行的累积接种对两种珊瑚幼体的细菌群落组成都有很强的影响。虽然没有评估细菌细胞在珊瑚宿主体内的位置，但使用16S rRNA基因的元条形码分析显示，与对照幼体相比，通过混合物施用的七种细菌菌株中的两种和六种分别在接种的 和 的幼体中显著富集。尽管在相同环境中饲养，但 和 建立了明显不同的细菌群落，无论是在分类组成还是多样性测量方面。这些发现表明，珊瑚宿主因素以及环境细菌库在塑造珊瑚相关细菌群落组成中发挥作用。宿主因素可能包括微生物传播模式（水平传播与母体传播）和宿主特异性。虽然作为宿主相关微生物组成员包含在细菌接种物中的分类群的长期稳定性仍有待评估，但我们的结果为珊瑚微生物组操纵的可行性提供了支持，至少在实验室环境中是这样。
