Fig. 1

The metagenomic abundance of key elements of the methane production pathway Centre pane: the methane production pathway, plus ancillary reactions, showing enzyme classification (EC) numbers. Left pane: the abundance of each of the relevant EC numbers in our data set. Bar charts show percentage of reads mapped to each enzyme in the 8 samples, 4 pairs of cattle matched for breed (AA = Aberdeen Angus; L = Limousin cross) and diet (High or Medium concentrate). Grey bars are cattle selected for high methane production, white bars are cattle selected for low methane production. For every single enzyme, within each pair, the abundance of the enzyme is higher in high methane producers than in low methane producers. Right pane: heatmap of KEGG orthologues for the EC numbers involved in methane production (lines connect the heatmap to the methane production pathway indicating which K0 numbers represent the given enzymes). The heatmap shows pairs of cattle matched for breed (AA = Aberdeen Angus; L = Limousin cross) and diet (High or Medium concentrate). Blue represents low abundance and yellow represents high abundance. Within each pair, the high methane emitters are to the right and the low methane emitters to the left. A clear pattern emerges – within each pair, these K0 numbers are more abundant (yellow) in the high methane emitters than in the low methane emitters