Table 1.
Abbreviations used for groups of animals and groups of rumen samples.
Table 2.
Overview of animals screened for CH4 yields and rumen samples collected for microbial community structure analysis.
Figure 1.
Densities of archaeal 16S rRNA genes in high- and low-CH4 emitting sheep.
Archaeal 16S rRNA genes (triangles) were quantified in 12 randomly-selected Hi and 12 randomly-selected Lo emitters of cohort 1, and are shown with their corresponding average CH4 yields (dots; each the mean of two consecutive days of measurement). Samples are ranked by average CH4 yield. Red triangles = number of archaeal 16S rRNA genes per g freeze-dried rumen content in Hi emitters collected in measuring round [a], orange triangles = number of archaeal 16S rRNA genes per g freeze-dried rumen content in Hi emitters collected in measuring round [b], blue triangles = number of archaeal 16S rRNA genes per g freeze-dried rumen content in Lo emitters collected in measuring round [a], light blue triangles = number of archaeal 16S rRNA genes per g freeze-dried rumen content in Lo emitters collected in measuring round [b]. Red dots = average CH4 yields of Hi emitters in measuring round [a], orange dots = average CH4 yields of Hi emitters in measuring round [b], blue dots = average CH4 yields of Lo emitters in measuring round [a], light blue dots = average CH4 yields of Lo emitters in measuring round [b]. Error bars represent the standard deviations of four technical replicates of quantitative PCR.
Figure 2.
Correlation of rumen microbial community structure with CH4 yields of sheep.
(A) Correspondence analysis of bacterial communities in 230 rumen samples revealed a relative abundance gradient of taxa across all samples. Samples of animals ranked as Lo emitters were represented more strongly at both tips of the graph, whereas samples of animals ranked as Hi emitters grouped more frequently in the center. (B) Differences of individual CH4 yields associated with each sample (n = 230) from the average CH4 yield for all samples (○) or for samples within each measuring round (•). A cubic polynomial function was fitted to the within measuring round data (black solid line), and 95% confidence and prediction bands are indicated as dashed blue and solid red lines, respectively. The samples are ordered from left to right corresponding to the order along the red arrow shown in panel (A). (C) Area plot of relative abundances of bacterial taxa in the 230 rumen samples sorted from left to right along the red arrow in panel (A) from top left to bottom right. The relative community composition in each sample is indicated by the colored segments. Q = Quinella ovalis, S = Sharpea azabuensis. For a detailed color key see Figure S5. (D) Relative abundance of species belonging to the archaeal genus Methanosphaera in 226 rumen samples of Hi and Lo emitters plotted from left to right along the red arrow in panel (A).
Table 3.
Analysis of variance between samples grouping into the three different bacterial community types.