Methanotrophy under extreme conditions : biochemistry and physiology of Methylacidiphilum fumariolicum SolV

• Main Author: Khadem, A.F.
• Other Authors: Jetten, M.S.M., Camp, H.J.M. op den, Pol, A.
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: [S.l.] : [S.n.] 2012
• Subjects: Ecological Microbiology; Hell's Gate; New Zealand; Kamchatka
• Online Access: http://hdl.handle.net/2066/98575; https://repository.ubn.ru.nl//bitstream/handle/2066/98575/98575.pdf

Contains fulltext : 98575.pdf (publisher's version ) (Open Access) Methane (CH4) is an important fossil fuel for households and industry, but also a trace gas in the atmosphere. Global warming is a worldwide concern and therefore it is important to increase knowledge of sources and sinks for methane. Fundamental knowledge about methanotrophic bacteria is important since they are sinks for methane diffusing from both biogenic and abiogenic sources. Until 2007, all genera of aerobic methanotrophs could be phylogenetically placed into the Alphaproteobacteria and Gammaproteobacteria. Intrigued by the observations that volcanic regions, characterized by a pH down to 1.8 and temperatures of 50-95 °C, may act as sinks for methane, recently (2007-2008) three research groups independently isolated obligate aerobic methanotrophs from these hostile environments in pure culture. Inocula were obtained from the Solfatara at Pozzuoli near Naples (Italy), Hell's Gate, Tikitere (New Zealand) and the Uzon Caldera, Kamchatka, (Russia). Excitingly, based on 16S rRNA gene sequences all three isolates (strains SolV, V4 and Kam1) could be identified as members of the Verrucomicrobia phylum. This is the first time that the widely distributed Verrucomicrobia phylum, from which most members remain uncultivated, is coupled to a geochemical cycle. This thesis focuses on one of these novel methanotrophs, e.g. Methylacidiphilum fumariolicum SolV isolated using mud from the central mud pool (Fangaia) of the Solfatara near Naples. Initial analyses of strain SolV showed major differences with the classical proteobacterial methanotrophs, e.g. extreme acid tolerance, absence of typical membrane structures, distinct enzymes of the methane oxidation and carbon fixation pathways. This was validated by combined approaches like genomics, electron microscopy, mRNA analyses, 13C-labeling and in this way the metabolism of strain SolV was unraveled in some details. This fundamental knowledge is necessary to assess the environmental importance of these ...