The Variation of Nasal Microbiota Caused by Low Levels of Gaseous Ammonia Exposure in Growing Pigs
The Variation of Nasal Microbiota Caused by Low Levels of Gaseous Ammonia Exposure in Growing Pigs
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DOI：
10.3389/fmicb.2019.01083
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发表时间：
2019-05
影响因子：
5.2
通讯作者：
Tongxin Wang;Qiongyu He;Weilei Yao;Yafei Shao;Ji Li;Feiruo Huang
中科院分区：
文献类型：
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作者：
Tongxin Wang;Qiongyu He;Weilei Yao;Yafei Shao;Ji Li;Feiruo Huang
暴露于气态氨，即使是低水平的，也可能对猪和人类健康有害。然而，关于持续暴露于气态氨对生长猪鼻腔微生物群定植的影响知之甚少。将120头杜×长×约克郡猪饲养在24个不同的小室中，连续暴露于0、5、10、15、20和25 ppm的气态氨（每个暴露水平4组）4周。然后，我们使用高通量测序技术对72头猪（n = 12）的鼻拭子样本进行16S rRNA基因分析。鼻微生物群分析结果表明，氨浓度的增加，尤其是在20和25 ppm时，会降低鼻微生物群的α多样性和相对丰度。变形菌门、厚壁菌门、拟杆菌门、放线菌门和绿弯菌门是最丰富的门。此外，24个微生物属的相对丰度随氨氮浓度的增加而发生显著变化。四种微生物属（假单胞菌属、乳杆菌属、普雷沃氏菌属和拟杆菌属）在25 ppm时显著减少，而只有两种属（莫拉氏菌属和链球菌属）在25 ppm时增加。PICRUSt分析表明，与细胞运动、信号转导、神经系统、环境适应以及能量和碳水化合物代谢有关的鼻微生物群的相对丰度显著降低，而与免疫系统、内分泌系统、循环系统、免疫系统疾病以及维生素、脂质和氨基酸代谢有关的基因随着氨水平的增加而增加。体内试验的结果表明，氨水平的增加，特别是25 ppm的氨水平，会导致呼吸道损伤，并增加莫拉氏菌和链球菌属物种的数量，同时降低呼吸免疫力和生长性能，这与通过鼻微生物群分析鉴定的有害细菌的存在增加一致。在此，本研究还表明，在养猪业中氨的阈值浓度为20 ppm。
Exposure to gaseous ammonia, even at low levels, can be harmful to pigs and human health. However, less is known about the effects of sustained exposure to gaseous ammonia on nasal microbiota colonization in growing pigs. A total of 120 Duroc×Landrace×Yorkshire pigs were housed in 24 separate chambers and continuously exposed to gaseous ammonia at 0,5, 10, 15, 20, and 25 ppm (four groups per exposure level) for 4 weeks. Then, we used high-throughput sequencing to perform 16S rRNA gene analysis in nasal swabs samples from 72 pigs (n = 12). The results of the nasal microbiota analysis showed that an increase in ammonia concentration, especially at 20 and 25 ppm, decreased the alpha diversity and relative abundance of nasal microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Chloroflexi were the most abundant phyla. In addition, the relative abundances of 24 microbial genera significantly changed as the ammonia level increased. Four microbial genera (Pseudomonas, Lactobacillus, Prevotella, and Bacteroides) were significantly decreased at 25 ppm, while only two genera (Moraxella and Streptococcus) were increased at 25 ppm. PICRUSt analyses showed that the relative abundances of the nasal microbiota involved in cell motility, signal transduction, the nervous system, environmental adaptation, and energy and carbohydrate metabolism were significantly decreased, while genes involved in the immune system, endocrine system, circulatory system, immune system diseases and metabolism of vitamins, lipid, and amino acids were increased with increased ammonia levels. The results of in vivo tests showed that an increase in ammonia levels, especially an ammonia level of 25 ppm, caused respiratory tract injury and increase the number of Moraxella and Streptococcus species, while simultaneously decreasing respiratory immunity and growth performance, consistent with the increased presence of harmful bacteria identified by nasal microbiota analysis. Herein, this study also indicted that the threshold concentration of ammonia in pig farming is 20 ppm.