title: Effect of Nickel Levels on Hydrogen Partial Pressure and Methane Production in Methanogens.
abstract: Hydrogen (H2) consumption and methane (CH4) production in pure cultures of three different methanogens were investigated during cultivation with 0, 0.2 and 4.21 μM added nickel (Ni). The results showed that the level of dissolved Ni in the anaerobic growth medium did not notably affect CH4 production in the cytochrome-free methanogenic species Methanobacterium bryantii and Methanoculleus bourgensis MAB1, but affected CH4 formation rate in the cytochrome-containing Methanosarcina barkeri grown on H2 and CO2. Methanosarcina barkeri also had the highest amounts of Ni in its cells, indicating that more Ni is needed by cytochrome-containing than by cytochrome-free methanogenic species. The concentration of Ni affected threshold values of H2 partial pressure (pH2) for all three methanogen species studied, with M. bourgensis MAB1 reaching pH2 values as low as 0.1 Pa when Ni was available in amounts used in normal anaerobic growth medium. To our knowledge, this is the lowest pH2 threshold recorded to date in pure methanogen culture, which suggests that M.bourgensis MAB1 have a competitive advantage over other species through its ability to grow at low H2 concentrations. Our study has implications for research on the H2-driven deep subsurface biosphere and biogas reactor performance.
authors.affiliation: Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
authors.forename: Anna
authors.identifier: http://orcid.org/0000-0002-1291-5529
authors.initials: A
authors.lastname: Neubeck
authors.affiliation: Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
authors.forename: Susanne
authors.initials: S
authors.lastname: Sjöberg
authors.affiliation: Department of Physical Sciences, The Open University, Milton Keynes, United Kingdom.
authors.forename: Alex
authors.initials: A
authors.lastname: Price
authors.affiliation: Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
authors.forename: Nolwenn
authors.initials: N
authors.lastname: Callac
authors.affiliation: Department of Microbiology, BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Schnürer
mesh_terms: D056804:Biofuels; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D006859:Hydrogen / Q000494:pharmacology*; D008697:Methane / Q000096:biosynthesis*; D017014:Methanobacterium / Q000254:growth & development / Q000378:metabolism*; D017021:Methanosarcina barkeri / Q000254:growth & development / Q000378:metabolism; D008828:Microbiological Techniques; D009532:Nickel / Q000494:pharmacology*; D010313:Partial Pressure
chemical_list: D056804:Biofuels; D003470:Culture Media; D002245:Carbon Dioxide; D009532:Nickel; D006859:Hydrogen; D008697:Methane