Weeks Denita M, Parris Matthew J, Brown Shawn P
Department of Biology, Grand Junction, Colorado Mesa University, Grand Junction, CO, 81501, USA.
Department of Biological Sciences, The University of Memphis, Memphis, TN, 38152, USA.
Anim Microbiome. 2020 Sep 22;2(1):35. doi: 10.1186/s42523-020-00053-5.
Microorganisms have intimate functional relationships with invertebrate and vertebrate taxa, with the potential to drastically impact health outcomes. Perturbations that affect microbial communities residing on animals can lead to dysbiosis, a change in the functional relationship, often associated with disease. Batrachochytrium dendrobatidis (Bd), a fungal pathogen of amphibians, has been responsible for catastrophic amphibian population declines around the globe. Amphibians harbor a diverse cutaneous microbiome, including some members which are known to be antagonistic to Bd (anti-Bd). Anti-Bd microorganisms facilitate the ability of some frog populations to persist in the presence of Bd, where other populations that lack anti-Bd microorganisms have declined. Research suggests disease-antagonistic properties of the microbiome may be a function of microbial community interactions, rather than individual bacterial species. Conservation efforts have identified amphibian-associated bacteria that exhibit anti-fungal properties for use as 'probiotics' on susceptible amphibian populations. Probiotic application, usually with a single bacterial species, may benefit from a greater understanding of amphibian species-specific microbiome responses to disturbances (e.g. dysbiosis vs. recovery). We assessed microbiome responses to two microbial disturbance events over multiple time points.
Exposing Lithobates sphenocephalus (southern leopard frog) adults to the biopesticidal bacteria Bacillus thuringiensis, followed by exposure to the fungal pathogen Bd, did not have long term impacts on the microbiome. After initial shifts, microbial communities recovered and returned to a state that resembled pre-disturbance.
Our results indicate microbial communities on L. sphenocephalus are robust and resistant to permanent shifts from some disturbances. This resiliency of microbial communities may explain why L. sphenocephalus is not experiencing the population declines from Bd that impacts many other species. Conservation efforts may benefit from studies outlining amphibian species-specific microbiome responses to disturbances (e.g. dysbiosis vs. recovery). If microbial communities on a threatened amphibian species are unlikely to recover following a disturbance, additional measures may be implemented to ameliorate the impacts of physical and chemical stressors on host-associated microbial communities.
微生物与无脊椎动物和脊椎动物类群有着密切的功能关系，有可能对健康结果产生重大影响。影响动物体表微生物群落的扰动会导致生态失调，即功能关系的改变，通常与疾病相关。蛙壶菌（Batrachochytrium dendrobatidis，Bd）是两栖动物的一种真菌病原体，在全球范围内导致两栖动物种群灾难性减少。两栖动物拥有多样的皮肤微生物群，其中一些成员已知对蛙壶菌具有拮抗作用（抗Bd）。抗Bd微生物使一些青蛙种群在有Bd的情况下仍能生存，而其他缺乏抗Bd微生物的种群数量则有所下降。研究表明，微生物群的疾病拮抗特性可能是微生物群落相互作用的结果，而非单个细菌物种的作用。保护工作已确定了具有抗真菌特性的两栖动物相关细菌，可作为“益生菌”应用于易感两栖动物种群。益生菌的应用通常使用单一细菌物种，若能更深入了解两栖动物物种特异性微生物群对干扰（如生态失调与恢复）的反应，可能会更有益处。我们在多个时间点评估了微生物群对两种微生物干扰事件的反应。
将北美豹蛙（Lithobates sphenocephalus）成体暴露于生物杀虫细菌苏云金芽孢杆菌，随后再暴露于真菌病原体Bd，对微生物群没有长期影响。在最初的变化之后，微生物群落恢复并回到了类似于干扰前的状态。
我们的结果表明，北美豹蛙体表的微生物群落具有很强的恢复力，能够抵抗某些干扰导致的永久性变化。微生物群落的这种恢复力可能解释了为什么北美豹蛙没有像许多其他物种那样因Bd而出现种群数量下降的情况。保护工作可能会受益于概述两栖动物物种特异性微生物群对干扰（如生态失调与恢复）反应的研究。如果受威胁两栖动物物种体表的微生物群在受到干扰后不太可能恢复，可能需要采取额外措施来减轻物理和化学应激源对宿主相关微生物群落的影响。
