大鲵皮肤溃疡死亡相关的微生物区系

为了分析自然环境中病死大鲵和健康大鲵皮肤及水样的微生物区系差异,实验通过高通量16S r DNA的V4～V5区测序,对皮肤微生物区系进行差异分析,探讨大鲵在患病前后微生物区系的变化。健康大鲵和病死大鲵生活水样以及皮肤菌群的多样性、结构和功能存在显著差异。各样品序列标签(Tag)数量平均为97 150条,测序平均长度为400 bp,操作分类单元(OTUs)数据显示,健康大鲵生活水样和皮肤的微生物丰度远远高于病死大鲵。在健康大鲵生活水样中的优势菌群为砷氧化菌属,而当大鲵病死后,其生活水样的优势菌群变为金黄杆菌属。同样,在病死大鲵皮肤样本中金黄杆菌属、丛毛单胞菌属、伯克氏菌目的微生物菌群丰度显著升高,而砷氧化菌属、微小杆菌属、莱比托泉动性球菌等微生物菌群丰度显著下降。同时,病死大鲵皮肤表面有大量溃疡并伴有菌毛,具有典型的伯克氏菌属感染症状。研究表明,大鲵患病死亡前后皮肤微生物区系差异明显,人兽共患病菌伯克氏菌属可能是通过水媒传播感染自然环境下的大鲵并导致死亡的主要病原菌,为科学养殖大鲵、保护野生大鲵以及开发益生菌改善大鲵养殖环境提供依据。

Diversity of microflora involved in skin ulcer and death of Andrias davidianus

[Objective] To explore the dynamics of microflora on diseased and healthy skin or water samples of Andrias davidianus in natural environment, and provide microbial basis for rational aquaculture, protection of wild Andrias davidianus and future development of probiotics to improve the breeding of Andrias davidianus. [Background] Andrias davidianus, commonly known as Chinese giant salamander, is a unique second-class protected wild animal in China. Andrias davidianus mainly distributed in karst caves of the Yangtze River and the Yellow River, and are regarded as aquatic pandas because of their high evolutionary distinctive and importance in the protection of global biodiversity resources. Recently, severe deaths caused by bacterial infection occurred in a breeding base of Andrias davidianus in Chongqing, which caused great economic losses. [Methods] In this study, the skin microflora of Andrias davidianus were profiled by high-throughput sequencing of the V4~V5 region of 16S rDNA gene, and the changes of skin microflora were compared between the healthy and the diseased Andrias davidianus. [Results] There were significant differences in the diversity, structure and function between healthy and diseased Andrias Davidianus skin bacteria. The average number of Tag of each sample was 97,150, and the average length of sequencing was 400 bp. The OTU data showed that the microbial abundance of healthy skin was much higher than that of diseased skin. The dominant bacteria in the living water samples of healthy Andrias davidianus was Aliihoeflea, and while the Andrias davidianus died, it changed to Chryseobacterium. The abundance of Chryseobacterium, Comamonas and Burkholderiales increased significantly, while that of Aliihoeflea, Exiguobacterium and Planococcus rifietoensis decreased significantly (P<0.05). Meanwhile, the skin surface of the dead Andrias davidianus has a large number of ulcers with pili, typical symptoms of Burkella infection. [Conclusion] Our findings confirmed that there were significant differences in skin microflora of diseased Andrias davidianus. Burkella zoonotic bacteria might be the main cause of the death of Andrias davidianus in natural environment contaminated by water vector. This provided basis for scientific breeding of Andrias davidianus.