Termite mounds contain soil-derived methanotroph communities kinetically adapted to elevated methane concentrations

Abstract Termite mounds have recently been confirmed to mitigate approximately half of termite methane (CH4) emissions, but the aerobic CH4 oxidising bacteria (methanotrophs) responsible for this consumption have not been resolved. Here, we describe the abundance, composition and CH4 oxidation kinetics of the methanotroph communities in the mounds of three distinct termite species sampled from Northern Australia. Results from three independent methods employed show that methanotrophs are rare members of microbial communities in termite mounds, with a comparable abundance but distinct composition to those of adjoining soil samples. Across all mounds, the most abundant and prevalent methane monooxygenase sequences were affiliated with upland soil cluster α (USCα), with sequences homologous to Methylocystis and tropical upland soil cluster (TUSC) also detected. The reconstruction of a metagenome-assembled genome of a mound USCα representative highlighted the metabolic capabilities of this group of methanotrophs. The apparent Michaelis–Menten kinetics of CH4 oxidation in mounds were estimated from in situ reaction rates. Methane affinities of the communities were in the low micromolar range, which is one to two orders of magnitude higher than those of upland soils, but significantly lower than those measured in soils with a large CH4 source such as landfill cover soils. The rate constant of CH4 oxidation, as well as the porosity of the mound material, were significantly positively correlated with the abundance of methanotroph communities of termite mounds. We conclude that termite-derived CH4 emissions have selected for distinct methanotroph communities that are kinetically adapted to elevated CH4 concentrations. However, factors other than substrate concentration appear to limit methanotroph abundance and hence these bacteria only partially mitigate termite-derived CH4 emissions. Our results also highlight the predominant role of USCα in an environment with elevated CH4 concentrations and suggest a higher functional diversity within this group than previously recognised.

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Termite mounds contain distinct methanotroph communities that are kinetically adapted to elevated methane concentrations

10.1101/717561 ◽

2019 ◽

Author(s):

Eleonora Chiri ◽

Chris Greening ◽

Stefan K. Arndt ◽

Philipp A. Nauer

Keyword(s):

Reaction Rates ◽

Termite Mound ◽

Predominant Role ◽

Termite Mounds ◽

Upland Soil ◽

Methane Oxidizing Bacteria ◽

Kinetics Of ◽

Micromolar Range

AbstractTermite mounds have recently been confirmed to mitigate approximately half of termite methane (CH4) emissions, but the aerobic methane-oxidizing bacteria (methanotrophs) responsible for this consumption have not been resolved. Here we describe the abundance, composition, and kinetics of the methanotroph communities in the mounds of three distinct termite species. We show that methanotrophs are rare members of the termite mound biosphere and have a comparable abundance, but distinct composition, to those of adjoining soil samples. Across all mounds, the most abundant and prevalent particulate methane monooxygenase sequences detected were affiliated with Upland Soil Cluster α (USCα), with sequences homologous to Methylocystis and Tropical Upland Soil Cluster also detected. The Michaelis-Menten kinetics of CH4 oxidation in mounds were estimated from in situ reaction rates. The apparent CH4 affinities of the communities were in the low micromolar range, which is one to two orders of magnitude higher than those of upland soils, but significantly lower than those measured in soils with a large CH4 source such as landfill-cover soils. The rate constant of CH4 oxidation, as well as the porosity of the mound material, were significantly positively correlated with the abundance of methanotroph communities of termite mounds. We conclude that termite-derived CH4 emissions have selected for unique methanotroph communities that are kinetically adapted to elevated CH4 concentrations. However, factors other than substrate concentration appear to limit methanotroph abundance and hence these bacteria only partially mitigate termite-derived CH4 emissions. Our results also highlight the predominant role of USCα in an environment with elevated CH4 concentrations and suggest a higher functional diversity within this group than previously recognised.

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Phosphorylation of GAPVD1 Is Regulated by the PER Complex and Linked to GAPVD1 Degradation

International Journal of Molecular Sciences ◽

10.3390/ijms22073787 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3787

Author(s):

Hussam Ibrahim ◽

Philipp Reus ◽

Anna Katharina Mundorf ◽

Anna-Lena Grothoff ◽

Valerie Rudenko ◽

...

Keyword(s):

Circadian Clock ◽

Transcriptional Repression ◽

Small Gtpase ◽

Main Role ◽

Interacting Proteins ◽

Casein Kinase 1 ◽

Bona Fide ◽

Kinetics Of

Repressor protein period (PER) complexes play a central role in the molecular oscillator mechanism of the mammalian circadian clock. While the main role of nuclear PER complexes is transcriptional repression, much less is known about the functions of cytoplasmic PER complexes. We found with a biochemical screen for PER2-interacting proteins that the small GTPase regulator GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1), which has been identified previously as a component of cytoplasmic PER complexes in mice, is also a bona fide component of human PER complexes. We show that in situ GAPVD1 is closely associated with casein kinase 1 delta (CSNK1D), a kinase that regulates PER2 levels through a phosphoswitch mechanism, and that CSNK1D regulates the phosphorylation of GAPVD1. Moreover, phosphorylation determines the kinetics of GAPVD1 degradation and is controlled by PER2 and a C-terminal autoinhibitory domain in CSNK1D, indicating that the regulation of GAPVD1 phosphorylation is a novel function of cytoplasmic PER complexes and might be part of the oscillator mechanism or an output function of the circadian clock.

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Effect of pH on the Grain Size Dependence of Magnesium Corrosion

CORROSION ◽

10.5006/i0010-9312-68-6-507 ◽

2012 ◽

Vol 68 (6) ◽

pp. 507-517 ◽

Cited By ~ 50

Author(s):

K. D. Ralston ◽

G. Williams ◽

N. Birbilis

Keyword(s):

Grain Size ◽

Corrosion Rate ◽

Anodic Polarization ◽

Localized Corrosion ◽

Anodic Reaction ◽

Left Behind ◽

Kinetics Of ◽

Electrode Technique

Prior works show that grain size can play a role in the corrosion of a metal; however, such works are nominally executed in a single electrolyte/environment at a single pH. In this work, the anodic and cathodic reaction kinetics of pure Mg specimens with grain sizes ranging from approximately 8 μm to 590 μm were compared as a function of pH in 0.1 mol dm−3 sodium chloride (NaCl) electrolytes using anodic polarization experiments and an in situ scanning vibrating electrode technique (SVET). Anodic polarization experiments showed that grain size is important in determining overall electrochemical response, but the environment dictates the form of the grain size vs. corrosion rate relationship (i.e., pH is the overall controlling factor). Consequently, the role of grain size upon corrosion cannot be fully assessed unless a variation in environment is simultaneously studied. For example, the anodic reaction, which dictates active corrosion, also dictates passivation, so the corrosion rate vs. grain size relationship has been shown to “flip” depending on pH. Further, SVET analysis of unpolarized Mg immersed in 0.1 mol dm−3 NaCl electrolyte at neutral pH showed that breakdown of passivity of cast Mg occurred after ~1 h immersion, giving filiform-like corrosion tracks. The front edges of these corrosion features were revealed as intense local anodes, while the remainder of the dark-corroded Mg surface, left behind as the anodes traversed the surface, became cathodically activated. In contrast, grain-refined Mg samples were significantly less susceptible to localized corrosion, and breakdown was not observed for immersion periods of up to 24 h.

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Effects of Solvent Polarity on the Urethane Reaction of 1,2-Propanediol

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.450-451.38 ◽

2012 ◽

Vol 450-451 ◽

pp. 38-41

Author(s):

Peng Fei Yang

Keyword(s):

Rate Constant ◽

Solvent Polarity ◽

Reaction Rates ◽

Phenyl Isocyanate ◽

Second Order Reaction ◽

Polar Solvents ◽

Initial Stage ◽

Ft Ir ◽

Kinetics Of

The urethane reaction kinetics of 1,2-propanediol with phenyl isocyanate are investigated in different solvents, such as xylene, toluene and dimethylformamide. In-situ FT-IR is used to monitor the reaction to work out rate constant. It showsthat the urethane reaction has been found to be a second order reaction, solvents largely affects reaction rates. The reaction is largely accelerated in polar solvents, following the order of dimethylformamide > toluene > xylene. Further more, when dimethylformamide is used as solvent, the rate constants are different between initial stage and final stage, which belongs to different hydroxyls in 1,2-propanediol. However, when toluene or xylene is used as solvent, the rate constant is the same. That is, there is no reactivity difference for hydroxyls in 1,2-propanediol.

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Kinetics of hydrosilylation of tert-butylphenylketone by diphenylsilane catalysed by [Rh(1,5-COD)(-)-DIOP]+ClO-4

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19802224 ◽

1980 ◽

Vol 45 (8) ◽

pp. 2224-2239 ◽

Cited By ~ 10

Author(s):

Ivan Kolb ◽

Jiří Hetflejš

Keyword(s):

Activation Parameters ◽

Reaction Rates ◽

Reaction Model ◽

Initial Reaction ◽

Title Reaction ◽

Rate Determining Step ◽

Kinetic Isotope ◽

Arene Complex ◽

Kinetics Of

Kinetic analysis of the title reaction has been made by the method of initial reaction rates. On the basis of the rate data, kinetic isotope effect and spectroscopic study of the reaction of the organosilicon hydride with the catalyst, the reaction model was proposed involving the following steps: the displacement of the diene by reaction with the silicon hydride from a rhodium-arene complex in an induction period of the hydrosilylation, the oxidative addition of the organosilicon hydride to the rhodium-arene complex, followed by the interaction of the ketone with the silylhydridorhodium (III) species in the rate determining step. The process is characterized by the following activation parameters: ΔU = 54.5 ± 8.5 kJ mol-1 and ΔS = -88± 25 J mol-1.K-1. The significant role of the entropic factor was supported by the analysis of the temperature dependence of the asymmetric efficiency of the catalyst.

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The Distal Ligamentous Complex of the Scaphoid and the Scapho-Lunate Ligament. An Anatomic, Histological and Biomechanical study

Journal of Hand Surgery (European Volume) ◽

10.1016/0266-7681(93)90200-y ◽

1993 ◽

Vol 18 (1) ◽

pp. 65-69 ◽

Cited By ~ 36

Author(s):

A. BOABIGHI ◽

J. N. KUHLMANN ◽

C. KENESI

Keyword(s):

Biomechanical Study ◽

Carpal Instability ◽

Predominant Role ◽

Fresh Cadaver ◽

Biomechanical Features

22 fresh cadaver specimens have been examined to study the anatomy, histology and biomechanical features of the ligaments of the proximal and distal poles of the scaphoid. The biomechanical study was carried out by two methods: an analytical one on an Instron machine, and a global one in situ. The different experiments show the predominant role of the distal ligamentous complex of the scaphoid over the scapho-lunate ligament. This contrasts with the generally accepted concept and modifies the management of lateral carpal instability.

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Termite mounds mitigate half of termite methane emissions

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1809790115 ◽

2018 ◽

Vol 115 (52) ◽

pp. 13306-13311 ◽

Cited By ~ 22

Author(s):

Philipp A. Nauer ◽

Lindsay B. Hutley ◽

Stefan K. Arndt

Keyword(s):

Feeding Habits ◽

Field Tests ◽

Tracer Test ◽

Transport Processes ◽

Termite Mounds ◽

Termite Species ◽

Field Methods ◽

Independent Field ◽

Species Specific

Termites are responsible for ∼1 to 3% of global methane (CH4) emissions. However, estimates of global termite CH4emissions span two orders of magnitude, suggesting that fundamental knowledge of CH4turnover processes in termite colonies is missing. In particular, there is little reliable information on the extent and location of microbial CH4oxidation in termite mounds. Here, we use a one-box model to unify three independent field methods—a gas-tracer test, an inhibitor approach, and a stable-isotope technique—and quantify CH4production, oxidation, and transport in three North Australian termite species with different feeding habits and mound architectures. We present systematic in situ evidence of widespread CH4oxidation in termite mounds, with 20 to 80% of termite-produced CH4being mitigated before emission to the atmosphere. Furthermore, closing the CH4mass balance in mounds allows us to estimate in situ termite biomass from CH4turnover, with mean biomass ranging between 22 and 86 g of termites per kilogram of mound for the three species. Field tests with excavated mounds show that the predominant location of CH4oxidation is either in the mound material or the soil beneath and is related to species-specific mound porosities. Regardless of termite species, however, our data and model suggest that the fraction of oxidized CH4(fox) remains well buffered due to links among consumption, oxidation, and transport processes via mound CH4concentration. The meanfoxof 0.50 ± 0.11 (95% CI) from in situ measurements therefore presents a valid oxidation factor for future global estimates of termite CH4emissions.

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Steps of Surface Etching and Carbon Deposition on the Graphite Basal Plane

MRS Proceedings ◽

10.1557/proc-312-225 ◽

1993 ◽

Vol 312 ◽

Cited By ~ 1

Author(s):

Xi Chu ◽

Vincent Chan ◽

Lanny D. Schmidt

Keyword(s):

Single Crystal ◽

Vapor Deposition ◽

Basal Plane ◽

Carbon Deposition ◽

Chemical Vapor ◽

Reaction Rates ◽

Plane Versus ◽

Graphite Basal Plane ◽

Kinetics Of

AbstractThe reactions of O2, H2O, CO2, NO2, NO, and N2O with single crystal graphite between 400 and 700°C have been studied by STM to obtain quantitative kinetics by measuring the number and size of monolayer pits on the basal plane versus temperature and time. At low temperature the reaction initiates exclusively from the point defects on the basal plane to form monolayer pits. The shape of the monolayer pits vary from nearly triangular to hexagonal to circular depending on the rate of the reaction and the reacting gases. The sizes of the monolayer pits grow linearly with reacting time. The monolayer reaction rates follow the order of RNO2 > RN2O > RNO > RO2 > RH2O > RCO2. The activation energies for reactions with O2, H2O, NO2, NO, and N2O, are determined to be 127, 205, 60, 89, and 74 kJ/mol respectively.Carbon deposition from hydrocarbons onto surfaces of single crystal graphite has been examined to study the fundamental steps of chemical vapor deposition. Uniform monolayer pits on graphite surface were first produced by reactive etching of freshly cleaved single crystal of graphite in oxygen and carbon was then made to deposit exclusively on these defects in the basal plane. Carbon vapor deposition forms unique structures around the monolayer steps. By measuring the sizes of structures on steps in various gases versus temperature and pressure, the kinetics of hydrocarbon decomposition and the role of surface diffusion can be determined.

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The Effect of Different Oxidizing Atmospheres on the Initial Kinetics of Copper Oxidation as Studied In Situ UHV-TEM

MRS Proceedings ◽

10.1557/proc-589-389 ◽

1999 ◽

Vol 589 ◽

Author(s):

Mridula D. Bharadwaj ◽

Anu Gupta ◽

J. Murray Gibson ◽

Judith C. Yang

Keyword(s):

Water Vapor ◽

High Vacuum ◽

Ultra High Vacuum ◽

Solid State Reactions ◽

Copper Oxidation ◽

High Vacuum Condition ◽

Ultra High Vacuum Condition ◽

Kinetics Of

AbstractEffect of moisture on the oxidation of copper was studied using in situ UHV-TEM. The ultra high vacuum condition is required for minimum contamination effects. The initial observations show that the water vapor reduces the oxide as well as reduces the rate of oxidation if both oxygen gas and water vapor are simultaneously used. Based on these observations, we have speculated on the role of moisture in the solid state reactions involved in copper oxidation

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