Interaction between methanotrophy and gastrointestinal nematodes infection on the rumen microbiome of lambs

Complex cross-talk occurs between gastrointestinal nematodes and gut symbiotic microbiota, with consequences for animal metabolism. To investigate the connection between methane production and endoparasites, this study evaluated the effect of mixed infection with Haemonchus contortus and Trichostrongylus colubriformis on methanogenic and methanotrophic community in rumen microbiota of lambs using shotgun metagenomic and real-time quantitative PCR (qPCR). The rumen content was collected from six Santa Inês lambs, (7 months old) before and after 42 days infection by esophageal tube. The metagenomic analysis showed that the infection affected the microbial community structure leading to decreased abundance of methanotrophs bacteria, i.e. α-proteobacteria and β-proteobacteria, anaerobic methanotrophic archaea (ANME), protozoa, sulfate-reducing bacteria, syntrophic bacteria with methanogens, geobacter, and genes related to pyruvate, fatty acid, nitrogen, and sulfur metabolisms, ribulose monophosphate cycle, and Entner-Doudoroff Pathway. Additionally, the abundance of methanogenic archaea and the mcrA gene did not change. The co-occurrence networks enabled us to identify the interactions between each taxon in microbial communities and to determine the reshaping of rumen microbiome associations by gastrointestinal nematode infection. Besides, the correlation between ANMEs was lower in the animal's postinfection. Our findings suggest that gastrointestinal parasites potentially lead to decreased methanotrophic metabolism-related microorganisms and genes.