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Applied and Environmental Microbiology Sep 2020Industrial methanol production converts methane from natural gas into methanol through a multistep chemical process. Biological methane-to-methanol conversion under...
Industrial methanol production converts methane from natural gas into methanol through a multistep chemical process. Biological methane-to-methanol conversion under moderate conditions and using biogas would be more environmentally friendly. Methanotrophs, bacteria that use methane as an energy source, convert methane into methanol in a single step catalyzed by the enzyme methane monooxygenase, but inhibition of methanol dehydrogenase, which catalyzes the subsequent conversion of methanol into formaldehyde, is a major challenge. In this study, we used the thermoacidophilic methanotroph "" SolV for biological methanol production. This bacterium possesses a XoxF-type methanol dehydrogenase that is dependent on rare earth elements for activity. By using a cultivation medium nearly devoid of lanthanides, we reduced methanol dehydrogenase activity and obtained a continuous methanol-producing microbial culture. The methanol production rate and conversion efficiency were growth-rate dependent. A maximal conversion efficiency of 63% mol methanol produced per mol methane consumed was obtained at a relatively high growth rate, with a methanol production rate of 0.88 mmol/g (dry weight)/h. This study demonstrates that methanotrophs can be used for continuous methanol production. Full-scale application will require additional increases in the titer, production rate, and efficiency, which can be achieved by further decreasing the lanthanide concentration through the use of increased biomass concentrations and novel reactor designs to supply sufficient gases, including methane, oxygen, and hydrogen. The production of methanol, an important chemical, is completely dependent on natural gas. The current multistep chemical process uses high temperature and pressure to convert methane in natural gas to methanol. In this study, we used the methanotroph "" SolV to achieve continuous methanol production from methane as the substrate. The production rate was highly dependent on the growth rate of this microorganism, and high conversion efficiencies were obtained. Using microorganisms for the production of methanol might enable the use of more sustainable sources of methane, such as biogas, rather than natural gas.
Topics: Methane; Methanol; Verrucomicrobia
PubMed: 32631865
DOI: 10.1128/AEM.01188-20 -
Scientific Reports Jun 2022This study assessed the biogas and methane production potential of wastewater sludge generated from the beverage industry. The optimization of the biogas production...
This study assessed the biogas and methane production potential of wastewater sludge generated from the beverage industry. The optimization of the biogas production potential of a single fed-batch anaerobic digester was operated at different temperatures (25, 35, and 45 ℃), pH (5.5, 6.5, 7.5, 8.5, and 9.5), and organic feeding ratio (1:3, 1:4, 1:5, and 1:6) with a hydraulic retention time of 30 days. The methane and biogas productivity of beverage wastewater sludge in terms of volatile solid (VS) and volume was determined. The maximum production of biogas (15.4 m/g VS, 9.3 m) and methane content (6.3 m/g VS, 3.8 m) were obtained in terms of VS and volume at 8.5, 35 ℃, 1:3 of optimal pH, temperature, and organic loading ratio, respectively. Furthermore, the maximum methane content (7.4 m/g VS, 4.4 m) and biogas production potential (17.9 m/g VS, 10.8 m) were achieved per day at room temperature. The total biogas and methane at 35 ℃ (30 days) are 44.3 and 10.8 m/g VS, respectively, while at 25 ℃ (48 days) increased to 67.3 and 16.1 m/g VS, respectively. Furthermore, the electricity-generating potential of biogas produced at room temperature (22.1 kWh at 24 days) and optimum temperature (18.9 kWh) at 40 days was estimated. The model simulated optimal HRT (25 days) in terms of biogas and methane production at optimum temperature was in good agreement with the experimental results. Thus, we can conclude that the beverage industrial wastewater sludge has a huge potential for biogas production and electrification.
Topics: Beverages; Biofuels; Bioreactors; Electricity; Methane; Sewage; Wastewater
PubMed: 35650251
DOI: 10.1038/s41598-022-12811-3 -
The ISME Journal Oct 2023The preeminent source of biological methane on Earth is methyl coenzyme M reductase (Mcr)-dependent archaeal methanogenesis. A growing body of evidence suggests a...
The preeminent source of biological methane on Earth is methyl coenzyme M reductase (Mcr)-dependent archaeal methanogenesis. A growing body of evidence suggests a diversity of archaea possess Mcr, although experimental validation of hypothesized methane metabolisms has been missing. Here, we provide evidence of a functional Mcr-based methanogenesis pathway in a novel member of the family Archaeoglobaceae, designated Methanoglobus nevadensis, which we enriched from a terrestrial hot spring on the polysaccharide xyloglucan. Our incubation assays demonstrate methane production that is highly sensitive to the Mcr inhibitor bromoethanesulfonate, stimulated by xyloglucan and xyloglucan-derived sugars, concomitant with the consumption of molecular hydrogen, and causing a deuterium fractionation in methane characteristic of hydrogenotrophic and methylotrophic methanogens. Combined with the recovery and analysis of a high-quality M. nevadensis metagenome-assembled genome encoding a divergent Mcr and diverse potential electron and carbon transfer pathways, our observations suggest methanogenesis in M. nevadensis occurs via Mcr and is fueled by the consumption of cross-fed byproducts of xyloglucan fermentation mediated by other community members. Phylogenetic analysis shows close affiliation of the M. nevadensis Mcr with those from Korarchaeota, Nezhaarchaeota, Verstraetearchaeota, and other Archaeoglobales that are divergent from well-characterized Mcr. We propose these archaea likely also use functional Mcr complexes to generate methane on the basis of our experimental validation in M. nevadensis. Thus, divergent Mcr-encoding archaea may be underestimated sources of biological methane in terrestrial and marine hydrothermal environments.
Topics: Phylogeny; Hot Springs; Archaeoglobales; Methane; Archaea
PubMed: 37452096
DOI: 10.1038/s41396-023-01472-3 -
Measurements of methane and nitrous oxide in human breath and the development of UK scale emissions.PloS One 2023Exhaled human breath can contain small, elevated concentrations of methane (CH4) and nitrous oxide (N2O), both of which contribute to global warming. These emissions...
Exhaled human breath can contain small, elevated concentrations of methane (CH4) and nitrous oxide (N2O), both of which contribute to global warming. These emissions from humans are not well understood and are rarely quantified in global greenhouse gas inventories. This study investigated emissions of CH4 and N2O in human breath from 104 volunteers in the UK population, to better understand what drives these emissions and to quantify national-scale estimates. A total of 328 breath samples were collected, and age, sex, dietary preference, and smoking habits were recorded for every participant. The percentage of methane producers (MPs) identified in this study was 31%. The percentage of MPs was higher in older age groups with 25% of people under the age of 30 classified as MPs compared to 40% in the 30+ age group. Females (38%) were more likely to be MPs than males (25%), though overall concentrations emitted from both MP groups were similar. All participants were found to emit N2O in breath, though none of the factors investigated explained the differences in emissions. Dietary preference was not found to affect CH4 or N2O emissions from breath in this study. We estimate a total emission of 1.04 (0.86-1.40) Gg of CH4 and 0.069 (0.066-0.072) Gg of N2O in human breath annually in the UK, the equivalent of 53.9 (47.8-60.0) Gg of CO2. In terms of magnitude, these values are approximately 0.05% and 0.1% of the total emissions of CH4 and N2O reported in the UK national greenhouse gas inventories.
Topics: Humans; Aged; Greenhouse Gases; Nitrous Oxide; Methane; Carbon Dioxide; United Kingdom
PubMed: 38091323
DOI: 10.1371/journal.pone.0295157 -
Environmental Science & Technology Jul 2021We present an updated fuel-based oil and gas (FOG) inventory with estimates of nitrogen oxide (NO) emissions from oil and natural gas production in the contiguous US...
We present an updated fuel-based oil and gas (FOG) inventory with estimates of nitrogen oxide (NO) emissions from oil and natural gas production in the contiguous US (CONUS). We compare the FOG inventory with aircraft-derived ("top-down") emissions for NO over footprints that account for ∼25% of US oil and natural gas production. Across CONUS, we find that the bottom-up FOG inventory combined with other anthropogenic emissions is on average within ∼10% of top-down aircraft-derived NO emissions. We also find good agreement in the trends of NO from drilling- and production-phase activities, as inferred by satellites and in the bottom-up inventory. Leveraging tracer-tracer relationships derived from aircraft observations, methane (CH) and non-methane volatile organic compound (NMVOC) emissions have been added to the inventory. Our total CONUS emission estimates for 2015 of oil and natural gas are 0.45 ± 0.14 Tg NO/yr, 15.2 ± 3.0 Tg CH/yr, and 5.7 ± 1.7 Tg NMVOC/yr. Compared to the US National Emissions Inventory and Greenhouse Gas Inventory, FOG NO emissions are ∼40% lower, while inferred CH and NMVOC emissions are up to a factor of ∼2 higher. This suggests that NMVOC/NO emissions from oil and gas basins are ∼3 times higher than current estimates and will likely affect how air quality models represent ozone formation downwind of oil and gas fields.
Topics: Air Pollutants; Methane; Natural Gas; Oil and Gas Fields; Ozone
PubMed: 34161066
DOI: 10.1021/acs.est.0c07352 -
Fa Yi Xue Za Zhi Aug 2022At present, the death cases of simple asphyxiant gas acute poisoning are increasing sharply. Common asphyxiant gases in death cases include nitrogen, helium, carbon... (Review)
Review
At present, the death cases of simple asphyxiant gas acute poisoning are increasing sharply. Common asphyxiant gases in death cases include nitrogen, helium, carbon dioxide, methane, propane, laughing gas, etc. Simple asphyxiant gas has no affinity for biological matrices and escapes quickly, which puts forward new requirements for autopsy procedures, selection and collection of samples, laboratory analysis and identification. This paper reviews the research and development process of death cases caused by simple asphyxiant gas acute poisoning and put forwards the collection and analysis strategy of the samples in such cases. The most valuable biological samples in such cases should be lung tissues associated with the airways, followed by brain tissue and cardiac blood. Gaseous samples from the esophageal cavity, tracheal cavity, pulmonary bronchi, gastric and cardiac areas are also recommended as valuable samples. In the case of postmortem examination, the gas should be injected into gas sample bag directly. Biological materials such as tissue and blood should be directly sealed in head-space vials and analyzed by using the headspace gas chromatography-mass spectrometry.
Topics: Carbon Dioxide; Autopsy; Gas Chromatography-Mass Spectrometry; Methane; Nitrogen
PubMed: 36426696
DOI: 10.12116/j.issn.1004-5619.2021.310501 -
Environmental Science & Technology Jan 2021Septic systems are potentially a significant source of greenhouse gases (GHGs). The present study investigated GHGs from the blackwater septic systems that are widely...
Septic systems are potentially a significant source of greenhouse gases (GHGs). The present study investigated GHGs from the blackwater septic systems that are widely used especially in low- and middle-income countries. Ten blackwater septic tanks in Hanoi, Vietnam, were investigated using the floating chamber method. The average methane and carbon dioxide emission rates measured at the first compartment (65% of total capacity) of the septic tanks were 11.92 and 20.24 g/cap/day, respectively, whereas nitrous oxide emission was negligible. Methane emission rate was significantly correlated with septage oxidation-reduction potential (ORP) ( = -0.67, = 0.034), chemical oxygen demand mass ( = 0.78, = 0.007), and biochemical oxygen demand mass ( = 0.78, = 0.008), whereas it was not significantly correlated with water temperature ( = 0.26, = 0.47) and dissolved oxygen ( = -0.59, = 0.075) within the limited range: 30.6-31.7 °C and 0.03-0.34 mg-O/L. The methane emission rates from septic tanks accumulating septage for >5 years were significantly higher than those at 0-5 years ( = 0.016). These results suggest that lower ORP and higher biodegradable carbon mass, in association with longer septage storage periods are key conditions for methane emissions. To the best of our knowledge, this is the first study to characterize GHG emissions from septic systems.
Topics: Carbon Dioxide; Greenhouse Effect; Greenhouse Gases; Methane; Nitrous Oxide; Vietnam
PubMed: 33403851
DOI: 10.1021/acs.est.0c03418 -
Molecules (Basel, Switzerland) Oct 2022Switchgrass earned its place globally as a significant energy crop by possessing essential properties such as being able to control erosion, low cost of production,...
Switchgrass earned its place globally as a significant energy crop by possessing essential properties such as being able to control erosion, low cost of production, biomass richness, and appeal for biofuel production. In this study, the impact of a Ca(OH)-assisted thermal pretreatment process on the switchgrass variety Shawnee for methane fuel production was investigated. The Ca(OH)-assisted thermal pretreatment process was optimized to enhance the methane production potential of switchgrass. Solid loading (3-7%), Ca(OH) concentration (0-2%), reaction temperature (50-100 °C), and reaction time (6-16 h) were selected as independent variables for the optimization. Methane production was obtained as 248.7 mL CH gVS under the optimized pretreatment conditions. Specifically, a reaction temperature of 100 °C, a reaction time of 6 h, 0% Ca(OH), and 3% solid loading. Compared to raw switchgrass, methane production was enhanced by 14.5%. Additionally, the changes in surface properties and bond structure, along with the kinetic parameters from first order, cone, reaction curve, and modified Gompertz modeling revealed the importance of optimization.
Topics: Methane; Biofuels; Anaerobiosis; Biomass; Panicum; Crops, Agricultural
PubMed: 36296483
DOI: 10.3390/molecules27206891 -
Nature Communications May 2022Minerals are widely proposed to protect organic carbon from degradation and thus promote the persistence of organic carbon in soils and sediments, yet a direct link...
Minerals are widely proposed to protect organic carbon from degradation and thus promote the persistence of organic carbon in soils and sediments, yet a direct link between mineral adsorption and retardation of microbial remineralisation is often presumed and a mechanistic understanding of the protective preservation hypothesis is lacking. We find that methylamines, the major substrates for cryptic methane production in marine surface sediment, are strongly adsorbed by marine sediment clays, and that this adsorption significantly reduces their concentrations in the dissolved pool (up to 40.2 ± 0.2%). Moreover, the presence of clay minerals slows methane production and reduces final methane produced (up to 24.9 ± 0.3%) by a typical methylotrophic methanogen-Methanococcoides methylutens TMA-10. Near edge X-ray absorption fine structure spectroscopy shows that reversible adsorption and occlusive protection of methylamines in clay interlayers are responsible for the slow-down and reduction in methane production. Here we show that mineral-OC interactions strongly control methylotrophic methanogenesis and potentially cryptic methane cycling in marine surface sediments.
Topics: Carbon; Clay; Geologic Sediments; Methane; Methylamines
PubMed: 35581283
DOI: 10.1038/s41467-022-30422-4 -
The ISME Journal Nov 2023Deep marine sediments (>1mbsf) harbor ~26% of microbial biomass and are the largest reservoir of methane on Earth. Yet, the deep subsurface biosphere and controls on its...
Deep marine sediments (>1mbsf) harbor ~26% of microbial biomass and are the largest reservoir of methane on Earth. Yet, the deep subsurface biosphere and controls on its contribution to methane production remain underexplored. Here, we use a multidisciplinary approach to examine methanogenesis in sediments (down to 295 mbsf) from sites with varying degrees of thermal alteration (none, past, current) at Guaymas Basin (Gulf of California) for the first time. Traditional (C/C and D/H) and multiply substituted (CHD and CHD) methane isotope measurements reveal significant proportions of microbial methane at all sites, with the largest signal at the site with past alteration. With depth, relative microbial methane decreases at differing rates between sites. Gibbs energy calculations confirm methanogenesis is exergonic in Guaymas sediments, with methylotrophic pathways consistently yielding more energy than the canonical hydrogenotrophic and acetoclastic pathways. Yet, metagenomic sequencing and cultivation attempts indicate that methanogens are present in low abundance. We find only one methyl-coenzyme M (mcrA) sequence within the entire sequencing dataset. Also, we identify a wide diversity of methyltransferases (mtaB, mttB), but only a few sequences phylogenetically cluster with methylotrophic methanogens. Our results suggest that the microbial methane in the Guaymas subsurface was produced over geologic time by relatively small methanogen populations, which have been variably influenced by thermal sediment alteration. Higher resolution metagenomic sampling may clarify the modern methanogen community. This study highlights the importance of using a multidisciplinary approach to capture microbial influences in dynamic, deep subsurface settings like Guaymas Basin.
Topics: Geologic Sediments; Phylogeny; Euryarchaeota; Methane; RNA, Ribosomal, 16S
PubMed: 37596411
DOI: 10.1038/s41396-023-01485-y