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Subject: search.filters.subject.Methanosphaera

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    Isolation and characterization of Methanosphaera sp. ISO3-F5, a member of a novel and widespread species of rumen methanogens growing with methanol plus hydrogen
    (The Microbes, 2024-12-03) Jeyanathan J; Palevich N; Reilly K; Palevich FP; Maclean PH; Li D; Altermann E; Kim CC; van Scheepstal IM; Hoskin SO; Kelly WJ; Leahy SC; Attwood GT; Ronimus RS; Henderson G; Janssen PH
    Rumen methanogens predominantly fall into two physiological groups: hydrogenotrophs which use hydrogen (H2) to reduce carbon dioxide (CO2) to methane (CH4), and methylotrophs which use H2 to reduce methanol and methylamines as substrates for methanogenesis. We used a dilution to extinction approach to isolate two hydrogenotrophic Methanocatella spp. and four cultures of methylotrophic methanogens from sheep rumen contents. Three of the methylotrophs were stable mixed cultures containing methanogens belonging to different lineages of the order Methanomassiliicoccales and one was a pure Methanosphaera culture. Methanosphaera sp. ISO3-F5 has a comparatively large genome (2.68 Mb) comprised of two replicons, a chromosome and a megaplasmid. The genome has an average G + C content of 30.5 % and encodes 2360 putative protein-coding genes. Cells of ISO3-F5 have a spherical shape, 0.6–1.2 µm in diameter, usually occurring in pairs or loose clumps, and have no flagellum. Cells stain Gram positive, have a single thick cell wall and divide by the formation of a cross wall. The optimum temperature for growth was 39°C to 42°C and the optimum pH was 6.7–6.8. Acetate was required for growth, but CH4 was not produced from acetate, formate, ethanol, methylamine, or isopropanol with or without H2/CO2. Volatile fatty acids and rumen fluid were also found to enhance the growth of ISO3-F5, while coenzyme M did not. ISO3-F5 produced CH4 from methanol in the presence of H2 and the genes encoding the necessary methanogenesis pathway have been identified. Based on morphological, physiological, and genomic characteristics, ISO3-F5 is a new species of the genus Methanosphaera. Our study shows that simple isolation methods allowed us to culture diverse and significant members of the rumen methanogen community.
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    Complete genome sequence of Methanosphaera sp. ISO3-F5, a rumen methylotrophic methanogen.
    (American Society for Microbiology, 2024-04-11) Palevich N; Jeyanathan J; Reilly K; Palevich FP; Maclean PH; Li D; Altermann E; Kelly WJ; Leahy SC; Attwood GT; Ronimus RS; Henderson G; Janssen PH; Stedman KM
    Methanosphaera spp. are methylotrophic methanogenic archaea and members of the order Methanobacteriales with few cultured representatives. Methanosphaera sp. ISO3-F5 was isolated from sheep rumen contents in New Zealand. Here, we report its complete genome, consisting of a large chromosome and a megaplasmid (GenBank accession numbers CP118753 and CP118754, respectively).
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    Identification of rumen methanogens, characterization of substrate requirements and measurement of hydrogen thresholds : a thesis presented in partial fulfilment of the requirements for the degree of Master 's in Microbiology
    (Massey University, 2012) Kim, Caroline Chae-hyun
    In New Zealand, exported farmed commodities derived from ruminants make up about one-third of the nation’s economy. However, farming ruminants creates a significant environmental impact by emitting methane which is a by-product of the microbial fermentation occurring in the rumen. Accumulated methane in the atmosphere is considered to be an important contributing factor to global warming and climate change. Methanogenic archaea, collectively called methanogens, inhabiting the rumen are responsible for the production of ruminal methane. These organisms are capable of anaerobically reducing CO2 to CH4, using H2, formate, methanol, a range of methyl-compounds, or acetate as electron-donors. Currently, all known methanogens that have been isolated from a diverse range of habitats are classified into 28 genera and 113 species based on the study of pure cultures and analysis of small subunit rRNA gene sequence data. Less than 10% of these species were isolated from the rumen and these reflect only a small portion of the true rumen methanogen diversity that has been determined by cultivation-independent methods. This project has been derived from the necessity to characterise genome sequences of a greater diversity of rumen methanogens than is currently covered in public culture collections. 14 methanogen strains were isolated as pure cultures and identified based on 16S rRNA and mcrA gene sequences in order to create a comprehensive phylogenetic tree comparing the genetic distances between the newly identified strains and the few named species. Strains 229/11, AbM4, M1, SM9, G16, D5, BRM9, YCM1, ISO3-F5, and A4 were then selected to be characterised for their substrate requirements for growth, by systematically omitting single or multiple components from the growth medium. Finally, the threshold levels of hydrogen, below which the methanogens fail to use it as a substrate, were measured for these strains by gas chromatography. Overall, the H2 thresholds of rumen methanogens fell within the range between 0.5 and 5.8 Pa. Methanobrevibacter, the most predominant group of methanogens occurring in the rumen, had relatively higher H2 thresholds compared to the genus Methanosphaera, a group of methanogens frequently isolated from New Zealand ruminants, and the genus Methanobacterium.