Abstract
Previous shotgun metagenomic analyses of ruminal digesta identified some microbial information that might be useful as
biomarkers to select cattle that emit less methane (CH4), which is a potent greenhouse gas. It is known that methane production
(g/kgDMI) and to an extent the microbial community is heritable and therefore biomarkers can offer a method of selecting cattle
for low methane emitting phenotypes.
In this study a wider range of Bos Taurus cattle, varying in breed and diet, was investigated to determine microbial communities
and genetic markers associated with high/low CH4 emissions. Digesta samples were taken from 50 beef cattle, comprising four
cattle breeds, receiving two basal diets containing different proportions of concentrate and also including feed additives (nitrate
or lipid), that may influence methane emissions. A combination of partial least square analysis and network analysis enabled the
identification of the most significant and robust biomarkers of CH4 emissions (VIP>0.8) across diets and breeds when comparing all
potential biomarkers together. Genes associated with the hydrogenotrophic methanogenesis pathway converting carbon dioxide
to methane, provided the dominant biomarkers of CH4 emissions and methanogens were the microbial populations most closely
correlated with CH4 emissions and identified by metagenomics. Moreover, these genes grouped together as confirmed by network
analysis for each independent experiment and when combined. Finally, the genes involved in the methane synthesis pathway
explained a higher proportion of variation in CH4 emissions by PLS analysis compared to phylogenetic parameters or functional
genes. These results confirmed the reproducibility of the analysis and the advantage to use these genes as robust biomarkers of
CH4 emissions.
Volatile fatty acid concentrations and ratios were significantly correlated with CH4, but these factors were not identified as
robust enough for predictive purposes. Moreover, the methanotrophic Methylomonas genus was found to be negatively correlated
with CH4. Finally, this study confirmed the importance of using robust and applicable biomarkers from the microbiome as a proxy
of CH4 emissions across diverse production systems and environments.
Original language | English |
---|---|
Article number | 2642 |
Number of pages | 15 |
Journal | Frontiers in Microbiology |
Volume | 8 |
Early online date | 9 Jan 2018 |
DOIs | |
Publication status | First published - 9 Jan 2018 |
Bibliographical note
1030565Keywords
- Biomarkers
- DIETS
- Metagenomics
- Methane
- Rumen microbiome