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dc.contributor.advisorTveit, Alexander
dc.contributor.authorSchmider, Tilman
dc.date.accessioned2024-05-27T10:10:44Z
dc.date.available2024-05-27T10:10:44Z
dc.date.issued2024-06-11
dc.description.abstractAtmospheric methane oxidizing bacteria (atmMOB) are the only known organisms that can consume methane (CH<sub>4</sub>) directly from the air. Therefore, they are referred to as biological CH<sub>4</sub> sink. CH<sub>4</sub> is a potent greenhouse gas, and its increasing atmospheric concentration accelerates global warming. By consuming the CH<sub>4</sub> from the air, atmMOB mitigate global warming. Despite the discovery of atmMOB in soils worldwide, the research on atmMOB stagnated as these bacteria have escaped isolation for decades. In 2019, the isolation of an atmMOB, named <i>Methylocapsa gorgona</i>, eventually succeeded. <i>Methylocapsa gorgona</i> is capable of growing “on air” (i.e., with air as sole carbon and energy source). In this PhD thesis, building on <i>Methylocapsa gorgona</i>, it was studied how atmMOB can grow on air. To do so, a set of methods specifically designed to study atmMOB has been established. Besides Methylocapsa gorgona, five additional bacterial species that also might have the potential to grow on air were investigated. In total, four of the six bacterial species could grow on air, increasing the number of known atmMOB isolates from one to four. Additionally, the atmMOB were found to cover their nitrogen requirements from air. A combination of three characteristics was identified as basis of the atmMOB to grow on air: All species consumed hydrogen (H<sub>2</sub>) and/or carbon monoxide (CO), two gases that are also in air, in addition to CH<sub>4</sub>; all species need less energy than previously assumed; and all species consumed CH<sub>4</sub> from air quickly enough to get the needed energy. Additionally, during growth on air, the atmMOB grew slower and increased the number of proteins that help them to consume CH<sub>4</sub>, CO, and/or H<sub>2</sub>. For the first time, this thesis shows the strategies that atmMOB use to grow on air and it challenges previous assumptions about their energy needs and their diversity. The findings further suggest that more atmMOB grow on air than previously assumed and that their impact on the global carbon cycle has been underestimated. Also, their role in mitigating global warming might be more important as they consume the indirect greenhouse gases H<sub>2</sub> and CO in addition to the potent greenhouse gas CH<sub>4</sub>. Finally, this thesis and the developed methods are promising steppingstones to utilize atmMOB in the future, for example to filter the potent greenhouse gas CH<sub>4</sub>, and to predict changes in the biological CH<sub>4</sub> sink caused by global warming and increasing greenhouse gas concentrations.en_US
dc.description.abstractAtmosfærisk metanoksiderende bakterier (atmMOB) utgjør det eneste kjente biologiske opptaket av metan (CH<sub>4</sub>) fra atmosfæren. De oksiderer den potente drivhusgassen CH<sub>4</sub> ved atmosfærisk konsentrasjon og bidrar dermed til å dempe global oppvarming. Til tross for funn av atmMOB i jord over hele verden stagnerte forskningen på atmMOB ettersom metanotrofe bakterier som vedvarende oksiderer atmosfærisk CH<sub>4</sub>, ikke lot seg isolere i flere tiår. I 2019 lyktes det endelig å isolere en atmMOB, <i>Methylocapsa gorgona</i>, som er i stand til å vokse "på luft" (dvs. med luft som eneste karbon- og energikilde). Basert på denne isolaten av atmMOB har de fysiologiske strategiene og de metabolske egenskapene som muliggjør metanotrof vekst på luft blitt undersøkt i løpet av denne doktorgradsavhandlingen. For å gjøre dette har et sett med metoder spesielt designet for bakteriekulturer som vokser på filtre som flyter på medium, blitt etablert. Dette inkluderer målinger av oksidasjon av sporgasser, cellekvantifisering, komparativ proteomikk og 15N-basert isotopmerking. I tillegg til <i>M. gorgona</i>, ble ytterligere fem metanotrofe arter undersøkt for evnen til å vokse på luft og deres fysiologiske strategier. Totalt kunne fire av de seks metanotrofe artene, inkludert tre utenfor den kanoniske atmMOB-gruppen USCα, vokse på luft, noe som firedoblet antallet kjente atmMOB i renkultur. I tillegg ble det etablert at atmMOB også dekker sitt nitrogenbehov fra luft. En kombinasjon av tre fysiologiske egenskaper ble identifisert som grunnlaget for at atmMOB kan vokse på luft: En mixotrof livsstil, ettersom alle artene oksiderte atmosfærisk hydrogen (H<sub>2</sub>) og/eller karbonmonoksid (CO) i tillegg til CH<sub>4</sub>; energikrav til vekst under energiverdien som tidligere ble antatt nødvendig for cellulært vedlikehold; og høy tilsynelatende spesifikk affinitet for CH<sub>4</sub>. På et metabolsk nivå reduserte atmMOB investeringer i biosyntese mens de økte investeringer i oksidasjon av spor-gasser under vekst på luft. Som et første omfattende arbeid på atmMOB i renkultur, avslører denne avhandlingen strategier hos atmMOB til å vokse på luft, og utfordrer tidligere oppfatninger av energibegrensninger for aerob vekst og fylogenetikken til atmMOB. Funnene tyder på at atmosfæren støtter større atmMOB-populasjoner enn antatt, noe som indikerer at deres globale distribusjon og innvirkning på den globale karbonsyklusen har blitt undervurdert. Også deres rolle i å dempe global oppvarming kan være viktigere enn antatt ettersom de forbruker de indirekte drivhusgassene H<sub>2</sub> og CO i tillegg til CH<sub>4</sub>. De rene atmMOB-kulturene og metodene utviklet i denne avhandlingen, er lovende byggesteiner for å modellere sammenhengen mellom stigende atmosfæriske CH<sub>4</sub>-nivåer, global oppvarming og det biologiske opptaket av atmosfærisk CH<sub>4</sub>, og for å vurdere potensialet til atmMOB for biofiltrering av lav-CH<sub>4</sub>-utslipp og andre bioteknologiske applikasjoner.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractAtmospheric methane oxidizing bacteria (atmMOB) are the only known organisms that can consume methane (CH4) directly from the air. Therefore, they are referred to as biological CH4 sink. CH4 is a potent greenhouse gas, and its increasing atmospheric concentration accelerates global warming. By consuming the CH4 from the air, atmMOB mitigate global warming. Despite the discovery of atmMOB in soils worldwide, the research on atmMOB stagnated as these bacteria have escaped isolation for decades. In 2019, the isolation of an atmMOB, named Methylocapsa gorgona, eventually succeeded. Methylocapsa gorgona is capable of growing “on air” (i.e., with air as sole carbon and energy source). In this PhD thesis, building on Methylocapsa gorgona, it was studied how atmMOB can grow on air. To do so, a set of methods specifically designed to study atmMOB has been established. Besides Methylocapsa gorgona, five additional bacterial species that also might have the potential to grow on air were investigated. In total, four of the six bacterial species could grow on air, increasing the number of known atmMOB isolates from one to four. Additionally, the atmMOB were found to cover their nitrogen requirements from air. A combination of three characteristics was identified as basis of the atmMOB to grow on air: All species consumed hydrogen (H2) and/or carbon monoxide (CO), two gases that are also in air, in addition to CH4; all species need less energy than previously assumed; and all species consumed CH4 from air quickly enough to get the needed energy. Additionally, during growth on air, the atmMOB grew slower and increased the number of proteins that help them to consume CH4, CO, and/or H2. For the first time, this thesis shows the strategies that atmMOB use to grow on air and it challenges previous assumptions about their energy needs and their diversity. The findings further suggest that more atmMOB grow on air than previously assumed and that their impact on the global carbon cycle has been underestimated. Also, their role in mitigating global warming might be more important as they consume the indirect greenhouse gases H2 and CO in addition to the potent greenhouse gas CH4. Finally, this thesis and the developed methods are promising steppingstones to utilize atmMOB in the future, for example to filter the potent greenhouse gas CH4, and to predict changes in the biological CH4 sink caused by global warming and increasing greenhouse gas concentrations.en_US
dc.description.sponsorshipThis thesis was supported by the Research Council of Norway FRIPRO Young Researcher Grant 315129, Living on Air, and by the Tromsø Research Foundation starting grant project Cells in the Cold 17_SG_ATT (both awarded to Alexander Tveit)en_US
dc.identifier.isbn978-82-8266-262-8
dc.identifier.urihttps://hdl.handle.net/10037/33622
dc.language.isoengen_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.relation.haspart<p>Paper 1: Tveit, A.T., Schmider, T., Hestnes, A.G., Lindgren, M., Didriksen, A. & Svenning, M.M. (2021). Simultaneous Oxidation of Atmospheric Methane, Carbon Monoxide and Hydrogen for Bacterial Growth. <i>Microorganisms, 9</i>, 153. Also available in Munin at <a href=https://hdl.handle.net/10037/20296>https://hdl.handle.net/10037/20296</a>. <p>Paper 2: Tilman Schmider, Anne Grethe Hestnes, Julia Brzykcy, Hannes Schmidt, Arno Schintlmeister, Benjamin R. K. Roller, Ezequiel Jesús Teran, Andrea Söllinger, Oliver Schmidt, Martin F. Polz, Andreas Richter, Mette M. Svenning, Alexander T. Tveit. Physiological Basis for Atmospheric Methane Oxidation and Methanotrophic Growth on Air. (Accepted manuscript). Now published in <i>Nature Communications, 15</i>, 4151 (2024), available at <a href=https://doi.org/10.1038/s41467-024-48197-1>https://doi.org/10.1038/s41467-024-48197-1</a>.en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2024 The Author(s)
dc.subject.courseIDDOKTOR-002
dc.subjectmethaneen_US
dc.subjecttrace gas oxidationen_US
dc.subjectmethanotrophsen_US
dc.subjectbioenergeticsen_US
dc.subjectphysiologyen_US
dc.subjectproteomicsen_US
dc.subjectmetabolismen_US
dc.subjectgreenhouse gas mitigationen_US
dc.titleLife on Air: On the Physiological Basis of Atmospheric Methane Oxidizing Bacteriaen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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