Weitzman Chava L, Brown Gregory P, Gibb Karen, Christian Keith
Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia.
School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.
Integr Zool. 2024 Jun 19. doi: 10.1111/1749-4877.12858.
Considerable research has focused on microbes on amphibian skin, as they act as the first line of defense against invading pathogens. This effort has generated substantial data on patterns across species, space, time, and ontogeny, alongside a growing list of beneficial antifungal symbionts. Though there is evidence of stability in amphibian skin microbial communities, there is also an indication that regular skin shedding reduces cultivable bacteria, with regrowth and recolonization in the period between sheds. This suggests that skin communities are in constant flux, and we lack an understanding of how the membership and structure of those communities are affected by shedding events. In this study, we conducted experiments on cane toads (Rhinella marina) to investigate the influence of shedding on skin microbiomes. We first used quantitative PCR to verify a positive correlation between bacterial loads and time in the days after shedding. We then resampled individuals over time to describe changes in community composition in the 38 h after shedding using amplicon sequencing. Similar to trends of bacterial loads, we found increases in alpha diversity over time after shedding, suggesting that shedding reduces bacterial diversity as it knocks down bacterial loads. During the 38-h period, community structure became similar to pre-shed communities in some individuals, but there was no consistent pattern in structural changes among individuals. In light of the amphibian chytridiomycosis pandemic, understanding how physiological events such as skin shedding affect beneficial bacteria and communities on amphibians would provide important insight into amphibian ecology.
大量研究聚焦于两栖动物皮肤上的微生物，因为它们是抵御入侵病原体的第一道防线。这项工作已经产生了关于跨物种、空间、时间和个体发育模式的大量数据，同时有益抗真菌共生体的名单也在不断增加。尽管有证据表明两栖动物皮肤微生物群落具有稳定性，但也有迹象表明定期蜕皮会减少可培养细菌，在两次蜕皮之间的时期会重新生长和重新定殖。这表明皮肤群落处于不断变化之中，而我们并不了解这些群落的成员和结构是如何受到蜕皮事件影响的。在本研究中，我们对蔗蟾蜍（海蟾蜍）进行了实验，以研究蜕皮对皮肤微生物群的影响。我们首先使用定量PCR来验证蜕皮后几天内细菌载量与时间之间的正相关关系。然后，我们随着时间对个体进行重新采样，使用扩增子测序来描述蜕皮后38小时内群落组成的变化。与细菌载量的趋势相似，我们发现蜕皮后随着时间推移α多样性增加，这表明蜕皮通过降低细菌载量而减少了细菌多样性。在38小时的时间段内，一些个体的群落结构变得与蜕皮前的群落相似，但个体之间的结构变化没有一致的模式。鉴于两栖动物壶菌病的大流行，了解诸如蜕皮等生理事件如何影响两栖动物身上的有益细菌和群落，将为两栖动物生态学提供重要的见解。
