Isolation and characterisation of novel Methanocorpusculum species indicates the genus is ancestrally host-associated

Abstract

AbstractBackgroundWith an increasing interest in the manipulation of methane produced from livestock cultivation, the microbiome of Australian marsupials provides a unique ecological and evolutionary comparison with ‘low-methane’ emitters. Previously, marsupial species were shown to be enriched for novel lineages ofMethanocorpusculum, as well asMethanobrevibacter,Methanosphaera, andMethanomassiliicoccales. Despite sporadic reports ofMethanocorpusculumfrom stool samples of various animal species, there remains little information on the impacts of these methanogens on their hosts.ResultsHere, we characterise novel host-associated species ofMethanocorpusculum, to explore unique host-specific genetic factors and their associated metabolic potential. We performed comparative analyses on 176Methanocorpusculumgenomes comprising 130 metagenome-assembled genomes (MAGs) recovered from 20 public animal metagenome datasets and 35 other publicly availableMethanocorpusculumMAGs and isolate genomes of host-associated and environmental origin. Nine MAGs were also produced from faecal metagenomes of the common wombat (Vombatus ursinus) and mahogany glider (Petaurus gracilis), along with the cultivation of one axenic isolate from each respective animal;M. vombati(sp. nov.) andM. petauri(sp. nov.).ConclusionsThrough our analyses, we substantially expand the available genetic information for this genus by describing the phenotypic and genetic characteristics of 23 host-associated species ofMethanocorpusculum. These lineages display differential enrichment of genes associated with methanogenesis, amino acid biosynthesis, transport system proteins, phosphonate metabolism, and carbohydrate-active enzymes. These results provide insights into the differential genetic and functional adaptations of these novel host-associated species ofMethanocorpusculumand suggest that this genus is ancestrally host-associated.