Revault Judith, Desdevises Yves, Magnanou Élodie
Sorbonne Université, CNRS, Biologie Intégrative des organismes marins, BIOM, Observatoire Océanologique, Banyuls/Mer, F-66650, France.
Anim Microbiome. 2024 Jul 30;6(1):42. doi: 10.1186/s42523-024-00329-0.
While teleost fishes represent two thirds of marine vertebrates, the role of their external microbiota in relationship with their environment remains poorly studied, especially in wild populations. Hence, the interaction of their microbiota with ectoparasites is largely unknown. Microbiota can act as a protective barrier against pathogens, and/or be involved in host recognition by parasites. Thus, host-parasite associations should now be considered as a tripartite interplay where the microbiota shapes the host phenotype and its relation to parasites. Monogeneans (Platyhelminthes) are direct life cycle ectoparasites commonly found on teleost skin and gills. The role of bacterial communities within skin and gill mucus which either pre-exist monogeneans infestation or follow it remain unclear. This is investigated in this study using the association between Sparidae (Teleostei) and their specific monogenean ectoparasites of the Lamellodiscus genus. We are exploring specificity mechanisms through the characterization of the external mucus microbiota of two wild sparid species using 16s rRNA amplicon sequencing. We investigated how these bacterial communities are related to constrated Lamellodiscus monogeneans parasitic load.
Our results revealed that the increase in Lamellodiscus load is linked to an increase in bacterial diversity in the skin mucus of D. annularis specimens. The date of capture of D. annularis individuals appears to influence the Lamellodiscus load. Correlations between the abundance of bacterial taxa and Lamellodiscus load were found in gill mucus of both species. Abundance of Flavobacteriaceae family was strongly correlated with the Lamellodiscus load in gill mucus of both species, as well as the potentially pathogenic bacterial genus Tenacibaculum in D. annularis gill mucus. Negative correlations were observed between Lamellodiscus load and the abundance in Vibrionaceae in gill mucus of D. annularis, and the abundance in Fusobacteria in gill mucus of P. acarne specimens, suggesting potential applications of these bacteria in mitigating parasitic infections in fish.
Our findings highlight the dynamic nature of fish microbiota, in particular in relation with monogeneans infestations in two wild sparid species. More generally, this study emphasizes the links between hosts, bacterial communities and parasites, spanning from the dynamics of co-infection to the potential protective role of the host's microbiota.
硬骨鱼占海洋脊椎动物的三分之二，但其外部微生物群与环境的关系仍研究不足，尤其是在野生种群中。因此，其微生物群与体外寄生虫的相互作用很大程度上未知。微生物群可作为抵御病原体的保护屏障，和/或参与寄生虫对宿主的识别。因此，宿主 - 寄生虫关联现在应被视为一种三方相互作用，其中微生物群塑造宿主表型及其与寄生虫的关系。单殖吸虫（扁形动物门）是常见于硬骨鱼皮肤和鳃上的直接生命周期体外寄生虫。在单殖吸虫感染之前或之后存在于皮肤和鳃黏液中的细菌群落的作用仍不清楚。本研究利用鲷科（硬骨鱼纲）与其特定的片盘虫属单殖吸虫体外寄生虫之间的关联对此进行了研究。我们通过使用16s rRNA扩增子测序对两种野生鲷科鱼类的外部黏液微生物群进行表征，探索特异性机制。我们研究了这些细菌群落如何与受限的片盘虫属单殖吸虫寄生负荷相关。
我们的结果表明，片盘虫负荷的增加与环状笛鲷标本皮肤黏液中细菌多样性的增加有关。环状笛鲷个体的捕获日期似乎会影响片盘虫负荷。在两种鱼类的鳃黏液中均发现了细菌类群丰度与片盘虫负荷之间的相关性。黄杆菌科的丰度与两种鱼类鳃黏液中的片盘虫负荷均密切相关，以及环状笛鲷鳃黏液中潜在致病细菌属——海杆菌属。在环状笛鲷鳃黏液中，片盘虫负荷与弧菌科的丰度之间以及在尖吻鲈标本鳃黏液中与梭杆菌科的丰度之间观察到负相关，表明这些细菌在减轻鱼类寄生虫感染方面的潜在应用。
我们的研究结果突出了鱼类微生物群的动态性质，特别是与两种野生鲷科鱼类中单殖吸虫感染的关系。更广泛地说，本研究强调了宿主、细菌群落和寄生虫之间的联系，从共感染的动态到宿主微生物群的潜在保护作用。
