The Draft Genome of the Non-Host-AssociatedMethanobrevibacter arboriphilusStrain DH1 Encodes a Large Repertoire of Adhesin-Like Proteins

Abstract

Methanobrevibacter arboriphilus strain DH1 is an autotrophic methanogen that was isolated from the wetwood of methane-emitting trees. This species has been of considerable interest for its unusual oxygen tolerance and has been studied as a model organism for more than four decades. Strain DH1 is closely related to other host-associated Methanobrevibacter species from intestinal tracts of animals and the rumen, making this strain an interesting candidate for comparative analysis to identify factors important for colonizing intestinal environments. Here, the genome sequence of M. arboriphilus strain DH1 is reported. The draft genome is composed of 2.445.031 bp with an average GC content of 25.44% and predicted to harbour 1964 protein-encoding genes. Among the predicted genes, there are also more than 50 putative genes for the so-called adhesin-like proteins (ALPs). The presence of ALP-encoding genes in the genome of this non-host-associated methanogen strongly suggests that target surfaces for ALPs other than host tissues also need to be considered as potential interaction partners. The high abundance of ALPs may also indicate that these types of proteins are more characteristic for specific phylogenetic groups of methanogens rather than being indicative for a particular environment the methanogens thrives in.

Comparative Genomic Analysis of Members of the GeneraMethanosphaeraandMethanobrevibacterReveals Distinct Clades with Specific Potential Metabolic Functions

“…species from termites and in Mbb. arboriphilus strain, has been reported previously [ 46 ], and these genes appear to be absent from species clades 2 to 4. It can only be speculated why Mbb.…”

“…Genes for methanol utilization of the Methanosphaera/Methanosarcina type (mtaABC) are distributed broadly within the genus Methanobrevibacter as outlined in Figure 1 and have also already been reported for some strains [46, 50]. Physiological characterizations of the strains that harbor mtaABC genes ( Mbb.…”

“…The potential utilization of alcohols, specifically methanol and ethanol, is also less clearly distributed among the 19 genomes (and the four different clades) and there are currently no known Methanobrevibacter species that are restricted to growth on H 2 and methanol/ethanol [ 10 ]. Genes for methanol utilization of the Methanosphaera/Methanosarcina type (mtaABC) are distributed broadly within the genus Methanobrevibacter as outlined in Figure 1 and have also already been reported for some strains [ 46 , 50 ]. Physiological characterizations of the strains that harbor mtaABC genes ( Mbb.…”

“…The Methanobrevibacter strains had been isolated from a range of different intestinal environments, for example, bovine and ovine rumen [ 12 , 41 ], human gut [ 42 ], and termite hindguts [ 43 , 44 ], but include also the genome of the non-host-associated Mbb. arboriphilus strain DSM 1125 T [ 45 , 46 ]. Results of the single- and multilocus analyses are shown in Figure 1 .…”

“…stadtmanae genome helped explaining some of the distinctive physiological features of this methanogen, but comparative genome analysis with other closely related Methanosphaera and Methanobrevibacter species was not possible at that time due to the lack of sequenced genomes. After more than a decade, several Methanosphaera and Methanobrevibacter genomes have become available [ 24 , 41 , 46 , 50 , 53 – 58 ] and comparative analyses allow determining whether certain traits are species specific or shared by members of either or both genera. Comparative genome analysis reveals that some of the observations made for the Msp.…”