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Copper availability, methanobactin production and methane oxidation in two Swiss lakes: Constraints on copper acquisition by methanotrophic bacteria

English title Copper availability, methanobactin production and methane oxidation in two Swiss lakes: Constraints on copper acquisition by methanotrophic bacteria
Applicant Lehmann Moritz
Number 160051
Funding scheme Project funding (Div. I-III)
Research institution Institut für Umweltgeowissenschaften Universität Basel
Institution of higher education University of Basel - BS
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.06.2016 - 30.11.2019
Approved amount 272'658.00
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All Disciplines (2)

Discipline
Hydrology, Limnology, Glaciology
Geochemistry

Keywords (10)

methanobactin; biomarker; microbial community structures; sulfide; copper in lakes; redox transition zone; methane oxidation; nutrient acquisition systems; radio-label incubations; south-alpine lakes

Lay Summary (German)

Lead
Methan ist ein potentes Treibhausgas. Es wird unter anaeroben Bedingungen in Feuchtgebieten und Seen produziert. Methan-oxidierenden Mikroorganismen dient es als Substrat. Aerobe Methanoxidierer benötigen Kupfer für den Aufbau eines wichtigen an der Methanoxidation beteiligten Enzyms. Kupferknappheit in natürlichen Gewässern kann wahrscheinlich von methanoxidierenden Bakterien durch aktive Kupferakquisition überwunden werden, wobei die Bakterien kupfer-affine organische Komponenten (Mathanobaktin) "aussenden" und so die Bioverfügbarkeit von Kupferverbindungen in ihrer unmittelbaren Umgebung erhöhen. Das Projekt zielt darauf ab, die Zusammenhänge zwischen Kupferverfügbarkeit und -Speziierung (und deren Kontrollmechanismen), Methanobaktinproduktion und bakterielle Methanoxidation unter kontrollierten Laborbedingungen sowie in natürlichen Gewässern zu verstehen.
Lay summary

A vast amount of the potent greenhouse gas methane (CH4) is produced and stored in natural wetlands and lakes. The multiple factors that can control aerobic methane oxidation in these environments are still not fully understood. In this interdisciplinary research program between the Universities of Basel and Vienna, we study the role of copper (Cu) as a functional constituent of a key enzyme in bacterial CH4 oxidation. Of particular interest are the mechanisms of, and controls on, bacterial Cu acquisition through the release of methanobactin (MB), a Cu-specific compound produced by methanotrophic bacteria to increase Cu availability and uptake. The existence of such a high affinity Cu uptake system implies that low Cu availability influences methanotrophic diversity and activity in natural environments. We will attempt to assess the distribution and temporal dynamics of MB in two Swiss lakes, expecting new insights into the environmental controls on MB production by methanotrophic bacteria and, in turn, CH4 oxidation under micro-aerobic conditions. Anticipating the important role of reduced sulfur compounds in modulating Cu speciation in aquatic environments, our main goal is to (1) address the role of sulfide as an important constraint on Cu-availability in freshwater, (2) to investigate the potential of MB exudation to increase the solubility and bioavailability of Cu-sulfides, and in turn (3) to assess whether MB production can enhance CH4 oxidation rates under Cu-limiting conditions in lakes. The efficiency of Cu acquisition by methanotrophic bacteria may have profound effects on the cycling of carbon and, possibly, the global climate. Furthermore, this study may be one of the starting points for research that addresses whether biochemical strategies developed by aerobic CH4 oxidizers to overcome Cu limitation may have been the evolutionary response to the competition for CH4 between anaerobic and aerobic CH4 oxidation.

 

Direct link to Lay Summary Last update: 11.02.2016

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
LSA Lugano/FH Lugano (Dr. M. Simona;Dr. M. Tonolla) Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
University of Vienna (Prof. Dr. S. Kraemer) Austria (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
GEOMAR (Marine Biogeochemistry) (Dr. Martha Gledhill) Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
ASLO Meetting, Honululu, Feb. 2017 Individual talk Spatiotemporal dynamics of methanotrophy in shelf seas: linking microbial activity with seasonal stratification and hypoxia 26.02.2017 Honululu, United States of America Steinle Lea;


Associated projects

Number Title Start Funding scheme
121861 Biogeochemical fluxes in South-Alpine Lakes: Linking nitrogen and methane dynamics in lacustrine redox-transition zones using a combined stable isotope and molecular approach 01.12.2008 Project funding (Div. I-III)
182043 Mechanism-Based Design, Synthesis, Biological Evaluation, and Delivery of Next-Generation Antibiotics 01.01.2019 Project funding (Div. I-III)
169552 The “methane paradox” in Lake Lugano - understanding methane production in oxygenated waters of lacustrine environments 01.01.2017 Project funding (Div. I-III)
183310 Ion Mobility Mass Spectrometry to Unscramble Complex Biological Samples 01.09.2019 R'EQUIP

Abstract

Methane (CH4) is a potent greenhouse gas with a much higher global warming potential than CO2. A vast amount of methane is produced and stored in natural wetlands and lakes. The multiple factors that can control aerobic methane oxidation in these environments are still not fully understood. We propose an international, interdisciplinary research program between the Universities of Basel and Vienna, in which hyphenated HPLC-MS, trace-metal geochemical, isotope, biomarker and molecular microbiological techniques, applied to experimental and field samples, are combined to allow for an in-depth investigation of the role of copper (Cu) as a functional constituent of a key enzyme in bacterial methane oxidation. Of particular interest are the mechanisms of, and controls on, bacterial Cu acquisition through the release of methanobactin (MB), a Cu specific compound produced by methanotrophic bacteria to increase Cu availability and uptake. The existence of such a high affinity Cu uptake system implies that low Cu availability influences methanotrophic diversity and activity in natural environments. We propose to assess for the first time the distribution and temporal dynamics of methanobactin in two Swiss lakes, expecting new insights into the environmental controls on chalcophore production by methanotrophic bacteria and, in turn, methane oxidation under micro-aerobic conditions in lacustrine redox-transition zones. Anticipating the important role of reduced sulfur compounds in modulating Cu speciation in aquatic environments, our main goals will be to (1) address the role of sulfide as an important constraint on Cu-availability in freshwater, (2) to investigate the potential of MB exudation to increase the solubility and bioavailability of Cu-sulfides, and in turn (3) to assess whether MB production can enhance methane oxidation rates under Cu-limiting conditions in lakes. Within the frame of two PhD projects we propose the following research questions: •Does Cu-availability impact and possibly limit aerobic methane oxidation in lakes?•Can methanotrophic bacteria actively overcome Cu limitation through the production of methanobactin? •Can we observe active methanobactin production in lakes and are there links between Cu, methanobactin concentrations, and methane oxidation rates?•How does Cu/sulfide interaction influence Cu speciation in a fresh water environment, and does the kinetic stability of soluble Cu-sulfide complexes at low oxygen levels decrease the bioavailability of Cu for methanotrophs?•Can Cu limitation trigger shifts of the lacustrine methanotrophic community composition?We will address these questions in a series of laboratory experiments and field measurements in the redox-transition zones of two lakes in Switzerland (Lake Lugano and Lake Cadagno). Established methods for the detection and quantification of MB will be optimized for low-concentrate analysis in the natural environment. We will search for links between Cu availability and speciation, sulfide concentrations, methanobactin production, suboxic methane oxidation rates and microbial population structure, and we will elucidate the geochemical mechanisms of bacterial Cu acquisition from sulfides. The efficiency of Cu acquisition by methanotrophic bacteria may have profound effects on the cycling of carbon and, possibly, the global climate. Furthermore, this study may be one of the starting points for research that addresses whether biochemical strategies developed by aerobic methane oxidizers to overcome Cu limitation may have been the evolutionary response to the competition for methane between anaerobic and aerobic methane oxidation.
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