McGrath-Blaser Sarah, Steffen Morgan, Grafe T Ulmar, Torres-Sánchez María, McLeod David S, Muletz-Wolz Carly R
Department of Biology, University of Florida, 421 Carr Hall, Gainesville, FL, 32611, USA.
Department of Biology, James Madison University, 951 Carrier Dr, Harrisonburg, VA, 22807, USA.
Anim Microbiome. 2021 Dec 20;3(1):83. doi: 10.1186/s42523-021-00147-8.
The amphibian skin microbiome is an important mediator of host health and serves as a potential source of undiscovered scientifically significant compounds. However, the underlying modalities of how amphibian hosts obtain their initial skin-associated microbiome remains unclear. Here, we explore microbial transmission patterns in foam-nest breeding tree frogs from Southeast Asia (Genus: Polypedates) whose specialized breeding strategy allows for better delineation between vertically and environmentally derived microbes. To facilitate this, we analyzed samples associated with adult frog pairs taken after mating-including adults of each sex, their foam nests, environments, and tadpoles before and after environmental interaction-for the bacterial communities using DNA metabarcoding data (16S rRNA). Samples were collected from frogs in-situ in Brunei, Borneo, a previously unsampled region for amphibian-related microbial diversity.
Adult frogs differed in skin bacterial communities among species, but tadpoles did not differ among species. Foam nests had varying bacterial community composition, most notably in the nests' moist interior. Nest interior bacterial communities were discrete for each nest and overall displayed a narrower diversity compared to the nest exteriors. Tadpoles sampled directly from the foam nest displayed a bacterial composition less like the nest interior and more similar to that of the adults and nest exterior. After one week of pond water interaction the tadpole skin microbiome shifted towards the tadpole skin and pond water microbial communities being more tightly coupled than between tadpoles and the internal nest environment, but not to the extent that the skin microbiome mirrored the pond bacterial community.
Both vertical influence and environmental interaction play a role in shaping the tadpole cutaneous microbiome. Interestingly, the interior of the foam nest had a distinct bacterial community from the tadpoles suggesting a limited environmental effect on tadpole cutaneous bacterial selection at initial stages of life. The shift in the tadpole microbiome after environmental interaction indicates an interplay between underlying host and ecological mechanisms that drive community formation. This survey serves as a baseline for further research into the ecology of microbial transmission in aquatic animals.
两栖动物的皮肤微生物群是宿主健康的重要调节因子，也是未被发现的具有重要科学意义的化合物的潜在来源。然而，两栖动物宿主如何获得其最初的皮肤相关微生物群的潜在方式仍不清楚。在这里，我们探索了东南亚泡沫巢繁殖树蛙（属：Polypedates）的微生物传播模式，其特殊的繁殖策略有助于更好地区分垂直来源和环境来源的微生物。为便于研究，我们使用DNA宏条形码数据（16S rRNA）分析了交配后与成年蛙对相关的样本，包括每只成年蛙的性别、它们的泡沫巢、环境以及环境相互作用前后的蝌蚪，以研究细菌群落。样本是在婆罗洲文莱的原位从青蛙身上采集的，该地区以前未对与两栖动物相关的微生物多样性进行过采样。
成年蛙的皮肤细菌群落在物种间存在差异，但蝌蚪在物种间没有差异。泡沫巢的细菌群落组成各不相同，最明显的是在巢的潮湿内部。每个巢的内部细菌群落都是离散的，与巢的外部相比，总体多样性较窄。直接从泡沫巢中采集的蝌蚪显示出的细菌组成与巢内部不太相似，而与成年蛙和巢外部的细菌组成更相似。经过一周的池塘水相互作用后，蝌蚪的皮肤微生物群向蝌蚪皮肤方向转变，并且蝌蚪皮肤和池塘水的微生物群落比蝌蚪与巢内部环境之间的耦合更紧密，但皮肤微生物群并没有完全反映池塘细菌群落。
垂直影响和环境相互作用在塑造蝌蚪皮肤微生物群方面都发挥了作用。有趣的是，泡沫巢内部的细菌群落与蝌蚪不同，这表明在生命的初始阶段，环境对蝌蚪皮肤细菌选择的影响有限。环境相互作用后蝌蚪微生物群的变化表明，潜在的宿主和生态机制之间存在相互作用，驱动群落形成。这项调查为进一步研究水生动物微生物传播生态学提供了基线。
