Institute of General Microbiology, Christian-Albrechts University Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany.
Sci Rep. 2019 Jan 10;9(1):34. doi: 10.1038/s41598-018-37321-z.
Multicellular organisms can be regarded as metaorganisms, comprising of a macroscopic host interacting with associated microorganisms. Within this alliance, the host has to ensure attracting beneficial bacteria and defending against pathogens to establish and maintain a healthy homeostasis. Here, we obtained several lines of evidence arguing that Aurelia aurita uses interference with bacterial quorum sensing (QS) - quorum quenching (QQ) - as one host defense mechanism. Three A. aurita-derived proteins interfering with bacterial QS were identified by functionally screening a metagenomic library constructed from medusa-derived mucus. Native expression patterns of these host open reading frames (ORFs) differed in the diverse life stages (associated with different microbiota) pointing to a specific role in establishing the developmental stage-specific microbiota. Highly increased expression of all QQ-ORFs in germ-free animals further indicates their impact on the microbiota. Moreover, incubation of native animals with pathogenic bacteria induced expression of the identified QQ-ORFs arguing for a host defense strategy against confronting bacteria by interference with bacterial QS. In agreement, immobilized recombinant QQ proteins induced restructuring of polyp-associated microbiota through changing abundance and operational taxonomic unit composition. Thus, we hypothesize that additional to the immune system host-derived QQ-activities potentially control bacterial colonization.
多细胞生物可以被视为元生物体，由与相关微生物相互作用的宏观宿主组成。在这种联盟中，宿主必须确保吸引有益细菌和抵御病原体，以建立和维持健康的体内平衡。在这里，我们获得了一些证据表明，海蜇使用干扰细菌群体感应（QS）-群体淬灭（QQ）-作为一种宿主防御机制。通过从水螅衍生的粘液构建的宏基因组文库的功能筛选，鉴定了三种干扰细菌 QS 的 Aurelia aurita 衍生蛋白。这些宿主开放阅读框（ORF）的天然表达模式在不同的生命阶段（与不同的微生物群相关）存在差异，这表明它们在建立发育阶段特异性微生物群方面具有特定的作用。无菌动物中所有 QQ-ORF 的高度表达进一步表明它们对微生物群的影响。此外，用致病性细菌孵育天然动物诱导了所鉴定的 QQ-ORF 的表达，这表明通过干扰细菌 QS 来对抗接触细菌的宿主防御策略。一致地，固定化重组 QQ 蛋白通过改变丰度和操作分类单元组成诱导息肉相关微生物群的重构。因此，我们假设除了免疫系统之外，宿主衍生的 QQ 活性可能控制细菌定植。
