大熊猫肠道菌群季节动态与营养利用

The giant panda is specific as a carnivora with a bamboo diet. It has been know that the gut microbiome of giant panda plays an essential role in the digestion of cellulose in bamboo for its host. However, there are still some uncertain problems about the relationship. On the second hand, giant pandas in wild tend to eat different species or different parts of bamboo in different seasons within one year. Therefore it comes the problem of the adaptation of giant panda's gut microbiome to the change of the diet. In present project,my group plans to collect fecal samples of wild giant panda in different seasons during which they eat different species or parts of bamboo in Qinling mountain. Then the metagenomic approaches will be performed on these samples. We also plan to collect bamboo samples of each seasons and perform nutritional analysis. We plan to discover the possible relationship of gut microbiome with the change of diet in different seasons. We are also looking forward to find some kinds of seasonal dynamics of gut microbiome in giant panda, either in the microbe diversity of the gut microbe community or the structure and function of metagenomic sequences, particularly in the metabolism of cellulose degradation. It would be an interesting question that whether such a dynamics could be related with the seasonal nutrition utilization of giant panda. With this project our group plans to accumulate essential and basic information on the conservation and management of the giant panda, as well as a substantial development on the research of metagenomics.

大熊猫作为独特的以竹子为食的食肉目动物，其肠道菌群对宿主的适应生理上有非常独特而重要的作用。在野外，大熊猫有规律地在不同时间采食不同种类的竹子乃至竹子的不同部分，一些研究认为这与大熊猫对食物的营养利用对策有关。因而大熊猫肠道菌群对食物营养利用的适应成为一个有趣的问题。本项目计划针对秦岭地区野外大熊猫展开，对不同时期的大熊猫同时采集粪便样品及作为食物的竹子样品（包括不同竹子或竹子的不同部位）。对粪便样品进行宏基因组分析，同时对竹子中的营养成分进行营养学分析。以此试图发现大熊猫肠道菌群在组成和功能上的季节动态变化，以及这些变化是否与其食物营养利用之间存在某种联系。通过这样的研究为大熊猫的适应生理研究及保护管理工作积累重要的基础信息。同时，期望通过此项目对肠道菌群的宏基因组学研究起推动作用。

野生大熊猫存在季节性的选择采食不同种类的竹子或竹子的不同部位的现象。本研究项目在秦岭佛坪保护区开展，采集不同季节野生大熊猫粪便样品，运用营养学手段和宏基因组学手段对大熊猫肠道微生物组的季节性变化与其采食竹子的营养利用的关系进行了研究。本研究将秦岭大熊猫季节性的食物变化分成三个阶段：叶期、笋期、转换期。其中，叶期从上年的9月到本年的4月；笋期从5月到7月中旬；转换期为整个8月。营养学分析显示，叶期的粗纤维和可溶性糖含量显著高于笋期，而蛋白质含量则是笋期显著高于叶期。16S rRNA靶向宏基因组测序得到了19480条read和156个OTU。结果显示叶期和笋期的肠道微生物明显分成两簇，而转换期则不规则地散落在两个簇内。笋期的肠道微生物的多样性比叶期明显的高。宏基因组测序得到了超过169Gbp的clean data数据和超过616Mbp的组装scaffold。深入的功能分析的结果显示，叶期的纤维素降解功能和遗传物质代谢的功能有显著加强，这提示了叶期的肠道微生物通过增强整个微生物群落的生态弹性来度过低营养期。而笋期表现出加强的功能可以分成两组，一组包括氨基酸转运、氨酰tRNA合成和脂肪酸降解通路，这组功能提示了提示了肠道微生物蛋白质合成的加强；另一组包括双组分系统、蛋白质输出和细菌分泌系统，这提示了在营养充足时期菌群-宿主联系的加强。