Milkov (2004) conservatively estimated global methane hydrate sources to be composed of ca. 1–5×1015 m3 in terms of methane. This amount of hydrated gas is approximately twice as much click here as that of natural gas present in all hydrocarbon reservoirs (Sloan and Koh, 2007). Methane in these reservoirs is mostly of biogenic origin (Koh et al., 2011). Hence, studies on methanogens associated with methane hydrate reservoirs are important.
A methanogen was isolated from deep sub seafloor methane hydrate sediment from the Krishna Godavari Basin off the eastern coast of India, following enrichment in MS medium (Boone et al., 1989) with H2 and CO2 as a source of carbon and energy and subsequent isolation using the roll tube method (Hungate, 1950). This isolate (designated as selleck inhibitor MH98A) was identified as a putative novel species of the genus Methanoculleus on the basis of its mcrA gene and 16S rRNA gene sequence featuring similarities of 94% and 99% respectively with the closest phylogenetic relative, Methanoculleus marisnigri JR1 (GenBank Accession No. NC_009051.1; Anderson et al.,
2009). Similar enrichment and isolation of methanogens was performed using MS medium supplemented with alternate substrates such as formate, acetate, methylamine and methanol. However, all isolates showed a similar phylogenetic affiliation. Hence, strain MH98A was believed to be the dominant methanogen principally contributing to methane hydrate deposits in the Krishna Godavari basin. Considering the enormous volumes of methane hydrate deposits in the region and Methanoculleus sp. MH98A as a dominant methanogen, gaining insights into the genome organization of MH98A was of immense interest to understand the methanogenesis that almost entirely contributes to the
vast methane hydrate deposits. Characterization of the methanogenic metabolism of this organism is crucial to deduce the magnitude and the energy content of methane hydrate deposits. To our best knowledge, genome sequences Clomifene of other methanogens associated with deep submarine methane hydrate deposits are not available so far. Further studies on these kinds of microorganisms to exploit their massive methanogenic potential could possibly revolutionize the energy industry. The genome of strain MH98A was sequenced using the Ion Torrent PGM sequencer (200-bp library) applying the 316™ sequencing chip according to the manufacturer’s instructions (Life Technologies, USA). De novo assembly was performed using version 4.0.5 of MIRA Assembler ( Chevreux et al., 1999) and generated 80 large contigs (> 8000 bp) and 226 smaller contigs (< 8000 bp) featuring a G + C content of 61.4%, an N50 value of 27533 bp, an N90 value of 4146 bp and a maximum contig size of 135,061 bp ( Table 1). All of 306 contigs were used for gene prediction and annotation by the RAST (Rapid Annotation using Subsystem Technology) system ( Aziz et al., 2008), with tRNAscan-SE-1.23 software ( Lowe and Eddy, 1997). RAST analysis revealed that, M.