Captive environments are maintained in hygienic ways that lack free-flowing microbes found in animals' natural environments. As a result, captive animals often have depauperate host-associated microbial communities compared to conspecifics in the wild and may have increased disease susceptibility and reduced immune function. Eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) have suffered precipitous population declines over the past few decades. To bolster populations, eastern hellbenders are reared in captivity before being translocated to the wild. However, the absence of natural microbial reservoirs within the captive environment diminishes the diversity of skin-associated bacteria on hellbender skin and may negatively influence their ability to defend against pathogenic species once they are released into the wild. To prepare hellbenders for natural bacteria found in riverine environments, we devised a novel bioaugmentation method to increase the diversity of skin microbial communities within a captive setting. We exposed juvenile hellbenders to increasing amounts of river water over 5 weeks before translocating them to the river. We genetically identified and phylogenetically compared bacteria collected from skin swabs and river water for alpha (community richness) and beta (community composition) diversity estimates. We found that hellbenders exposed to undiluted river water in captivity had higher alpha diversity and distinct differentiation in the community composition on their skin, compared to hellbenders only exposed to well water. We also found strong evidence that hellbender skin microbiota is host-specific rather than environmentally driven and is colonized by rare environmental operational taxonomic units in river water. This technique may increase hellbender translocation success as increasing microbial diversity is often correlated with elevated disease resistance. Future work is necessary to refine our methods, investigate the relationship between microbial diversity and hellbender health and understand how this bioaugmentation technique influences hellbenders' survival following translocation from captivity into the wild.

中文翻译：

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一种新颖的生物增强技术有效地提高了圈养东部黑b的皮肤相关微生物多样性。

圈养环境保持卫生，缺乏动物自然环境中自由流动的微生物。结果，与野生动物相比，圈养动物通常具有更弱的宿主相关微生物群落，并可能增加疾病易感性和降低免疫功能。在过去的几十年中，东部地狱动物（Cryptobranchus alleganiensis alleganiensis）的种群数量急剧下降。为了增强种群数量，东部地狱犬在被放逐到野外之前被人工饲养。但是，圈养环境中缺乏自然的微生物贮藏库，会减少黑帮皮肤上与皮肤相关的细菌的多样性，并且一旦它们释放到野外，可能会对它们抵抗病原体的能力产生负面影响。为了为在河流环境中发现的天然细菌制备地狱动物，我们设计了一种新型的生物强化方法，以在圈养环境中增加皮肤微生物群落的多样性。我们在5周内将未成年幼稚者暴露于越来越多的河水中，然后才将他们转移到河中。我们对从棉签和河水中收集的细菌进行了遗传鉴定和系统发育比较，以评估α（社区丰富度）和beta（社区组成）多样性。我们发现，与仅接触井水的地狱犬相比，被囚禁在未稀释河水中的地狱犬具有更高的阿尔法多样性和皮肤上群落组成的明显差异。我们还发现有力的证据表明，地狱犬的皮肤微生物群是特定于宿主的，而不是环境驱动的，并被河水中罕见的环境操作分类单位所定殖。由于增加的微生物多样性通常与提高的抗病能力有关，因此该技术可能会增加hellbender易位的成功率。未来的工作对于改进我们的方法，研究微生物多样性与海hell的健康之间的关系以及了解这种生物强化技术如何从人工饲养转入野外后如何影响海ender的生存是必要的。