Abstract：
Understanding normal microbial populations within areas of the respiratory tract is essential, as variable regional conditions create different niches for microbial flora, and proliferation of commensal microbes likely contributes to clinical respiratory disease. The objective was to describe microbial population variability between respiratory tract locations in healthy horses. Samples were collected from four healthy adult horses by nasopharyngeal lavage (NPL), transtracheal aspirate (TTA), and bronchoalveolar lavage (BAL) of six distinct regions within the lung. Full-length 16S ribosomal DNA sequencing and microbial profiling analysis was performed. There was a large amount of diversity, with over 1797 ASVs identified, reduced to 94 taxa after tip agglomeration and prevalence filtering. Number of taxa and diversity were highly variable across horses, sample types, and BAL locations. Firmicutes, proteobacteria, and actinobacteria were the predominant phyla. There was a significant difference in richness (Chao1, p=0.02) and phylogenetic diversity (FaithPD, p = 0.01) between NPL, TTA, and BAL. Sample type (p=0.03) and horse (p=0.005) contributed significantly to Bray-Curtis compositional diversity, while Weighted Unifrac metric was only affected by simplified sample type (NPL and TTA vs BAL, p=0.04). There was no significant effect of BAL locations within the lung with alpha or beta diversity statistical tests. Overall findings support diverse microbial populations that were variable between upper and lower respiratory tract locations, but with no apparent difference in microbial populations of the six biogeographic regions of the lung, suggesting that BAL fluid obtained blindly by standard clinical techniques may be sufficient for future studies in healthy horses.
摘要：
了解呼吸道区域内的正常微生物种群至关重要，由于可变的区域条件为微生物区系创造了不同的生态位，共生微生物的增殖可能导致临床呼吸道疾病。目的是描述健康马匹呼吸道位置之间的微生物种群差异。通过鼻咽灌洗（NPL）从四匹健康的成年马收集样本，经气管抽吸物（TTA），和肺内六个不同区域的支气管肺泡灌洗（BAL）。进行全长16S核糖体DNA测序和微生物谱分析。有大量的多样性，确认了超过1797辆ASV，在尖端聚集和流行过滤后减少到94个分类单元。类群的数量和多样性在不同的马之间差异很大，样品类型,和BAL位置。Firmicutes,蛋白细菌,放线菌是主要的门。丰富度（Chao1，p=0.02）和系统发育多样性（FaithPD，P=0.01)之间的不良贷款，TTA,和BAL。样本类型（p=0.03）和马（p=0.005）对Bray-Curtis成分多样性做出了显着贡献，而加权Unifrac度量仅受简化样本类型(NPL和TTAvsBAL，p=0.04)。通过α或β多样性统计检验，肺内BAL位置没有显着影响。总体研究结果支持不同的微生物种群，这些种群在上呼吸道和下呼吸道位置之间是可变的，但是肺的六个生物地理区域的微生物种群没有明显差异，提示通过标准临床技术盲目获得的BAL液可能足以用于健康马的未来研究。
