The distribution characteristics of aerosol bacteria in different types of sheepfolds

Abstract

With the development of modern sheep raising technology, the increasing density of animals in sheep house leads to the accumulation of microbial aerosols in sheep house. It is an important prerequisite to grasp the characteristics of bacteria in aerosols in sheep house to solve the problems of air pollution and disease prevention and control in sheep house. In this study, the microorganisms present in the air of sheep houses were investigated to gain insights into the structure of bacterial communities and the prevalence of pathogenic bacteria. Samples from six sheep pens in each of three sheep farms, totaling 18, were collected in August 2022 from Ningxia province, China. A high-volume air sampler was utilized for aerosol collection within the sheep housing followed by DNA extraction for 16S rRNA sequencing. Employing high-throughput 16S rRNA sequencing technology, we conducted an in-depth analysis of microbial populations in various sheep pen air samples, enabling us to assess the community composition and diversity. The results revealed a total of 11,207 operational taxonomic units (OTUs) within the bacterial population across the air samples, encompassing 152 phyla, 298 classes, 517 orders, 853 families, 910 genera, and 482 species. Alpha diversity and beta diversity analysis indicated that differences in species diversity, evenness and coverage between different samples. At the bacterial phylum level, the dominant bacterial groups are Firmicutes, Proteobacteria, and Actinobacteria, among which Firmicutes (97.90-98.43%) is the highest. At the bacterial genus level, bacillus, Bacteroides, Fusobacterium, etc. had higher abundance, with Bacillus (85.47-89.87%) being the highest. Through an in-depth analysis of microbial diversity and a meticulous examination of pathogenic bacteria with high abundance in diverse sheep house air samples, the study provided valuable insights into the microbial diversity, abundance, and distinctive features of prevalent pathogenic bacteria in sheep house air. These findings serve as a foundation for guiding effective disease prevention and control strategies within sheep farming environments.

Keywords: Miseq sequencing; microbial aerosols; microbial community structure and diversity; pathogenic bacteria; sheepfolds air.

Figure 1

Concentrations of culturable airborne bacteria in different sheep houses (data are expressed as mean ± SD. ^***p < 0.001). YCSH 1, YCSH 2, and YCSM represent three different sheep houses, respectively.

Figure 2

Grouped box diagram of Alpha diversity index. In each box chart, the Abscissa is the grouping label and the ordinate is the value of the corresponding alpha diversity index.

Figure 3

Sample two-dimensional sorting chart for PCoA analysis.

Figure 4

Wayne diagram of three groups of samples ASV/OTU. Each ellipse represents a group, the overlap area between ellipses indicates the common ASV/OTU between groups, and the number of each block indicates the number of ASV/OTU contained in the block.

Figure 5

The composition of the microbiota in the sheep house air. Relative abundance of community at the phylum (A), class (B) family (C), and genus (D).

Figure 6

Microbiota analysis using LEfSe was conducted on sheep samples. (A) Linear Discriminant Analysis (LDA) effect size (LEfSe) was applied to microbial communities in distinct forms, revealing significant differences (p < 0.05, LDA > 3). Nodes of varying colors and sizes represent microbial groups with notable disparities and enriched species abundance. Light yellow nodes indicate groups with no significant differences. Panel (B) illustrates LEfSe results for three specific regions.