Biology Department, Vassar College, 124 Raymond Avenue, Poughkeepsie, NY 12604, USA.
Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
FEMS Microbiol Ecol. 2022 Mar 24;98(3). doi: 10.1093/femsec/fiac023.
Variation in the structure of host-associated microbial communities has been correlated with the occurrence and severity of disease in diverse host taxa, suggesting a key role of the microbiome in pathogen defense. However, whether these correlations are typically a cause or consequence of pathogen exposure remains an open question, and requires experimental approaches to disentangle. In amphibians, infection by the fungal pathogen Batrachochytrium dendrobatidis (Bd) alters the skin microbial community in some host species, whereas in other species, the skin microbial community appears to mediate infection dynamics. In this study, we completed experimental Bd exposures in three species of tropical frogs (Agalychnis callidryas, Dendropsophus ebraccatus,andCraugastor fitzingeri) that were sympatric with Bd at the time of the study. For all three species, we identified key taxa within the skin bacterial communities that were linked to Bd infection dynamics. We also measured higher Bd infection intensities in D. ebraccatus and C. fitzingeri that were associated with higher mortality in C. fitzingeri. Our findings indicate that microbially mediated pathogen resistance is a complex trait that can vary within and across host species, and suggest that symbiont communities that have experienced prior selection for defensive microbes may be less likely to be disturbed by pathogen exposure.
宿主相关微生物群落结构的变化与不同宿主分类群中疾病的发生和严重程度有关，这表明微生物组在病原体防御中起着关键作用。然而，这些相关性通常是病原体暴露的原因还是结果，仍然是一个悬而未决的问题，需要通过实验方法来解决。在两栖动物中，真菌病原体蛙壶菌（Batrachochytrium dendrobatidis，Bd）的感染会改变某些宿主物种的皮肤微生物群落，而在其他物种中，皮肤微生物群落似乎介导了感染动态。在这项研究中，我们在三种热带青蛙（Agalychnis callidryas、Dendropsophus ebraccatus 和 Craugastor fitzingeri）中完成了实验性 Bd 暴露，这些青蛙在研究时与 Bd 共生。对于所有三种物种，我们确定了与 Bd 感染动态相关的皮肤细菌群落中的关键分类群。我们还发现，D. ebraccatus 和 C. fitzingeri 的 Bd 感染强度更高，与 C. fitzingeri 的死亡率更高有关。我们的研究结果表明，微生物介导的病原体抗性是一个复杂的特征，它可以在宿主物种内和跨宿主物种变化，并且表明经历过防御性微生物选择的共生体群落可能不太容易受到病原体暴露的干扰。
