Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo, Avenida Juanito Itzícuaro SN, Nueva Esperanza, 58330, Morelia, Michoacán, México.
Universidad Tecnológica de Morelia, Avenida Vicepresidente Pino Suárez 750, Cd. Industrial, 58200, Morelia, Michoacán, México.
Microb Ecol. 2021 Oct;82(3):666-676. doi: 10.1007/s00248-021-01706-x. Epub 2021 Feb 18.
Skin-associated bacteria are known to inhibit infection by the fungal pathogen Batrachochytrium dendrobatidis (Bd) in amphibians. It has also been postulated that skin-associated bacterial community is related to Bd infection intensity. However, our understanding of host microbial dynamics and their importance in regulating Bd intensity is limited. We analyzed Bd infection and skin-associated bacteria from two amphibian species, the salamander Ambystoma rivulare and the frog Lithobates spectabilis that co-occurred in a tropical high-altitude site in central Mexico. Sixty-three percent of sampled salamander individuals and 80% of frog individuals tested positive for Bd. Overall, we registered 622 skin-associated bacterial genera, from which 73 are known to have Bd inhibitory effects. These inhibitory taxa represented a relative abundance of 50% in relation to total relative bacterial abundance. Our results indicated that, although sharing some bacterial taxa, bacterial community from the skin of both species was different in taxonomic composition and in relative abundance. Pseudomonas spp. and Stenotrophomonas spp. were among the five most abundant bacterial taxa of both species. Both bacterial taxa inhibit Bd infection. We detected that bacterial richness and relative abundance of inhibitory Bd bacteria were negatively related to intensity of Bd infection independent of species and seasons. Despite the high Bd prevalence in both host species, no dead or sick individuals were registered during field surveys. The relatively low levels of Bd load apparently do not compromise survival of host species. Therefore, our results suggested that individuals analyzed were able to survive and thrive under a dynamic relation with enzootic infections of Bd and their microbiota.
皮肤相关细菌被认为可以抑制真菌病原体蛙壶菌（Batrachochytrium dendrobatidis，Bd）在两栖动物中的感染。有人还假设，皮肤相关细菌群落与 Bd 感染强度有关。然而，我们对宿主微生物动态及其在调节 Bd 强度方面的重要性的理解是有限的。我们分析了来自两种两栖动物物种的 Bd 感染和皮肤相关细菌，这两种物种分别是蝾螈 Ambystoma rivulare 和青蛙 Lithobates spectabilis，它们在墨西哥中部一个热带高海拔地区共同存在。抽样的蝾螈个体中有 63%和青蛙个体中有 80%检测出 Bd 阳性。总体而言，我们记录了 622 种皮肤相关细菌属，其中 73 种已知具有抑制 Bd 的作用。这些抑制性分类群在总相对细菌丰度中相对丰度为 50%。我们的研究结果表明，尽管两种物种的皮肤具有一些共同的细菌分类群，但在分类组成和相对丰度上，它们的细菌群落是不同的。假单胞菌属和寡养单胞菌属是两种物种中最丰富的五个细菌分类群之一。这两个细菌分类群都能抑制 Bd 的感染。我们发现，细菌丰富度和抑制性 Bd 细菌的相对丰度与 Bd 感染强度呈负相关，与物种和季节无关。尽管两种宿主物种的 Bd 患病率都很高，但在实地调查中没有发现死亡或患病的个体。Bd 负荷水平相对较低显然不会危及宿主物种的生存。因此，我们的研究结果表明，分析的个体能够在与 Bd 及其微生物群的地方性感染的动态关系中生存和茁壮成长。
