Expanding the cultivable human archaeome:Methanobrevibacter intestinisp. nov. and strainMethanobrevibacter smithii “GRAZ-2”from human feces

Abstract

AbstractTwo mesophilic, hydrogenotrophic methanogens, WWM1085 andM. smithiiGRAZ-2 were isolated from human fecal samples. WWM1085 was isolated from an individual in the USA, and represents a novel species with in the genusMethanobrevibacter.M. smithiiGRAZ-2 (= DSM 116045) was retrieved from fecal samples of a European, healthy female and represents a novel strain within this genus. BothMethanobrevibacterrepresentatives form non-flagellated, short rods with variable morphologies and the capacity to form filaments. Both isolates showed the typical fluorescence of F420and methane production.Compared toM. smithiiGRAZ-2, WWM1085 did not accumulate formate when grown on H2and CO2. The optimal growth conditions were at 37°C, and pH 7. Full genome sequencing revealed a genomic difference of WWM1085 to the type strain ofM. smithiiPS (type strain; DSM 861), with 93.55% ANI and major differences in the sequence of itsmcrAgene (3.3% difference in nucleotide sequence). Differences in the 16S rRNA gene were very minor and thus distinction based on this sequence might not be possible.M. smithiiGRAZ-2 was identified as a novel strain within theMethanobrevibactergenus (ANI 99.04 % toM. smithiiPS).Due to the major differences of WWM1085 andM. smithiitype strain PS in phenotypic, genomic and metabolic features, we proposeM. intestinisp. nov. as a novel species with WWM1085 as the type strain (DSM 116060T = CECT 30992).