Tang Ke-Yi, Wang Zhen-Wei, Wan Qiu-Hong, Fang Sheng-Guo
MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, China.
Changxing Yinjiabian Chinese Alligator Nature Reserve, Changxing, China.
Front Microbiol. 2019 Oct 25;10:2409. doi: 10.3389/fmicb.2019.02409. eCollection 2019.
As a natural hibernator, the Chinese alligator () is an ideal and intriguing model to investigate changes in microbial community structure and function caused by hibernation. In this study, we used 16S rRNA profiling and metagenomic analysis to compare the composition, diversity, and functional capacity in the gut microbiome of hibernating vs. active Chinese alligators. Our results show that gut microbial communities undergo seasonal restructuring in response to seasonal cycles of feeding and fasting in the Chinese alligator, but this animal harbors a core gut microbial community primarily dominated by Proteobacteria, Fusobacteria, Bacteroidetes, and Firmicutes across the gut regions. During hibernation, there is an increase in the abundance of bacterial taxa (e.g., the genus ) that can degrade host mucin glycans, which allows adaptation to winter fasting. This is accompanied by the enrichment of mucin oligosaccharide-degrading enzyme and carbohydrate-active enzyme families. In contrast, during the active phase (feeding), active Chinese alligators exhibit a carnivore gut microbiome dominated by Fusobacteria, and there is an increase in the relative abundance of bacteria (e.g., ) with known proteolytic and amino acids-fermentating functions that improve host protein-rich food digestion efficiency. In addition, seasonal variations in the expression of β-defensins play a protective role in intestinal immunity. These findings provide insights into the functional adaptations of host-gut microbe symbioses to seasonal dietary shifts to maintain gut homeostasis and health, especially in extreme physiological states.
作为一种天然的冬眠动物，扬子鳄是研究冬眠引起的微生物群落结构和功能变化的理想且有趣的模型。在本研究中，我们使用16S rRNA基因测序和宏基因组分析来比较冬眠期和活动期扬子鳄肠道微生物群的组成、多样性和功能能力。我们的结果表明，扬子鳄肠道微生物群落会随着季节性的摄食和禁食周期而发生季节性重组，但在整个肠道区域，这种动物拥有一个主要由变形菌门、梭杆菌门、拟杆菌门和厚壁菌门主导的核心肠道微生物群落。在冬眠期间，能够降解宿主粘蛋白聚糖的细菌类群（如属）丰度增加，这使得扬子鳄能够适应冬季禁食。同时，粘蛋白寡糖降解酶和碳水化合物活性酶家族也得到了富集。相比之下，在活动期（摄食），活动状态的扬子鳄表现出以梭杆菌门为主导的食肉动物肠道微生物群，并且具有已知蛋白水解和氨基酸发酵功能的细菌（如）相对丰度增加，从而提高了宿主对富含蛋白质食物的消化效率。此外，β-防御素表达的季节性变化在肠道免疫中发挥保护作用。这些发现为宿主-肠道微生物共生体对季节性饮食变化的功能适应提供了见解，以维持肠道稳态和健康，特别是在极端生理状态下。
