摘要
Dairy cattle are globally important agricultural animals. Central to their biology is the rumen, which houses an essential microbial community, or microbiome, important for providing nutrition from otherwise host-inaccessible dietary components. The rumen environment is noted for its substantial spatial heterogeneity, as illustrated by the stratification into ruminal solid and liquid phases. A third microbiota found directly attached to the ruminal epithelium (the epimural microbiota) also exists but is less well understood because of challenges in sampling the ruminal epithelium. As a result, our understanding of the epimural microbiota is based on analyses of cannulated animals sampled at a single location—the ventral sac—and does not account for other ruminal locations, which may have importance for overall rumen function. To address this knowledge gap, we hypothesize that the epimural microbiota at different ruminal locations differs due to known morphological, physiological, and functional differences across the geographic spread of the rumen epithelium. Here, we characterized bacterial epimural communities at different sites within 8 lactating Holstein dairy cows using 16S rRNA gene sequencing. Four different sites were sampled via rumen tissue biopsy: cranial sac (CS), ventral sac (VS), caudodorsal blind sac (CDBS), and caudoventral blind sac (CVBS). We found that locations differed in both epimural bacterial community structure and composition, with the CDBS community displaying the greatest diversity. Across all sampling sites, epimural bacterial communities were dominated by members of the phyla Bacteroidetes, Firmicutes, and Proteobacteria. Bacteria within Prevotellaceae, Butyrivibrio, Campylobacter, Mogibacterium, and Desulfobulbus all showed high relative sequence abundance and differential distributions according to sample location. There appears to be a core epimural microbiota present across all locations in all cows, although relative abundance was highly variable. The difference in relative abundance in epimural microbial communities, perhaps influenced by host physiology and the diversity within rumen contents, likely has important consequences for nutrition acquisition and general health. To the best of our knowledge, this work represents the first characterization of the ruminal epimural microbiota across different epithelial locations for any bovine ruminant.
摘要译文
奶牛是全球重要的农业动物。瘤胃是其生物学的中心，瘤胃中有一个重要的微生物群落或微生物组，对于从其他宿主（无法获得的饮食成分）中提供营养至关重要。瘤胃环境因其实质上的空间异质性而闻名，如瘤胃固相和液相分层所示。还存在直接附着在瘤胃上皮上的第三个微生物群（硬膜外微生物群），但由于取样瘤胃上皮的挑战，人们对其了解较少。结果，我们对硬膜外微生物群的了解是基于对在单个位置（腹囊）采样的插管动物的分析，而不是考虑其他瘤胃位置，这可能对整体瘤胃功能很重要。为了解决这一知识鸿沟，我们假设不同瘤胃位置的硬膜外菌群不同，这是由于瘤胃上皮的地理分布范围内已知的形态，生理和功能差异所致。在这里，我们使用16S rRNA基因测序表征了8头泌乳荷斯坦奶牛内不同部位的细菌硬膜外群落。通过瘤胃组织活检对四个不同的部位进行了采样：颅囊（CS），腹囊（VS），尾嗅盲囊（CDBS）和盲肠盲囊（CVBS）。我们发现，在硬膜外细菌群落结构和组成上位置都不同，其中CDBS群落表现出最大的多样性。在所有采样点，硬膜外细菌，硬毛虫和变形杆菌的成员主导着硬膜外细菌群落。根据样品的位置，原核科，肉芽孢杆菌，弯曲杆菌，动杆菌和脱硫球菌均显示较高的相对序列丰度和差异分布。尽管相对丰度变化很大，但在所有母牛的所有位置似乎都存在一个核心的硬膜外微生物群。硬膜外微生物群落相对丰度的差异可能受宿主生理和瘤胃内含物多样性的影响，可能对营养获取和整体健康产生重要影响。据我们所知，这项工作代表了任何牛反刍动物跨不同上皮位置的瘤胃硬膜外微生物群的第一个特征。
D.L.Sbardellati[1];A.Fischer[2];M.S.Cox[1];W.Li[2];K.F.Kalscheur[2];G.Suen[1]. The bovine epimural microbiota displays compositional and structural heterogeneity across different ruminal locations[J]. Journal of Dairy Science, 2020,103(4): 3636-3647