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Nature Communications Nov 2022Anaerobic methanotrophic (ANME) archaea obtain energy from the breakdown of methane, yet their extrachromosomal genetic elements are little understood. Here we describe...
Anaerobic methanotrophic (ANME) archaea obtain energy from the breakdown of methane, yet their extrachromosomal genetic elements are little understood. Here we describe large plasmids associated with ANME archaea of the Methanoperedens genus in enrichment cultures and other natural anoxic environments. By manual curation we show that two of the plasmids are large (155,605 bp and 191,912 bp), circular, and may replicate bidirectionally. The plasmids occur in the same copy number as the main chromosome, and plasmid genes are actively transcribed. One of the plasmids encodes three tRNAs, ribosomal protein uL16 and elongation factor eEF2; these genes appear to be missing in the host Methanoperedens genome, suggesting an obligate interdependence between plasmid and host. Our work opens the way for the development of genetic vectors to shed light on the physiology and biochemistry of Methanoperedens, and potentially genetically edit them to enhance growth and accelerate methane oxidation rates.
Topics: Archaea; Anaerobiosis; Methane; Oxidation-Reduction; Plasmids
PubMed: 36400771
DOI: 10.1038/s41467-022-34588-9 -
Global Change Biology Jan 2022The ongoing development of the Global Carbon Project (GCP) global methane (CH ) budget shows a continuation of increasing CH emissions and CH accumulation in the...
The ongoing development of the Global Carbon Project (GCP) global methane (CH ) budget shows a continuation of increasing CH emissions and CH accumulation in the atmosphere during 2000-2017. Here, we decompose the global budget into 19 regions (18 land and 1 oceanic) and five key source sectors to spatially attribute the observed global trends. A comparison of top-down (TD) (atmospheric and transport model-based) and bottom-up (BU) (inventory- and process model-based) CH emission estimates demonstrates robust temporal trends with CH emissions increasing in 16 of the 19 regions. Five regions-China, Southeast Asia, USA, South Asia, and Brazil-account for >40% of the global total emissions (their anthropogenic and natural sources together totaling >270 Tg CH yr in 2008-2017). Two of these regions, China and South Asia, emit predominantly anthropogenic emissions (>75%) and together emit more than 25% of global anthropogenic emissions. China and the Middle East show the largest increases in total emission rates over the 2000 to 2017 period with regional emissions increasing by >20%. In contrast, Europe and Korea and Japan show a steady decline in CH emission rates, with total emissions decreasing by ~10% between 2000 and 2017. Coal mining, waste (predominantly solid waste disposal) and livestock (especially enteric fermentation) are dominant drivers of observed emissions increases while declines appear driven by a combination of waste and fossil emission reductions. As such, together these sectors present the greatest risks of further increasing the atmospheric CH burden and the greatest opportunities for greenhouse gas abatement.
Topics: Animals; Atmosphere; China; Livestock; Methane; Oceans and Seas
PubMed: 34553464
DOI: 10.1111/gcb.15901 -
The Science of the Total Environment Oct 2021Ventilation Air Methane emissions (VAM) from coal mines lead to environmental concern because their high global warming potential and the loss of methane resources. VAM... (Review)
Review
Ventilation Air Methane emissions (VAM) from coal mines lead to environmental concern because their high global warming potential and the loss of methane resources. VAM upgrading requires pre-concentration processes dealing with high flow rates of very diluted streams (<1% methane). Therefore, methane separation and concentration is technically challenging and has important environmental and safety concerns. Among the alternatives, adsorption on Metal-Organic Frameworks (MOFs) could be an interesting option to methane selective separation, due to its tuneable character and outstanding physical properties. Most of the works devoted to the methane adsorption on MOFs deal with methane storage. Therefore, these works were reviewed to determine the properties governing methane-MOF interactions. In addition, the metallic ions and organic linkers roles have been identified. With these premises, decisive effects in the methane adsorption selectivity in nitrogen/methane lean mixtures have been discussed, since nitrogen is the most concentrated gas in the VAM stream, and it is very similar to methane molecule. In order to fulfill this overview, the effect of other aspects, such as the presence of polar compounds (moisture and carbon dioxide), was also considered. In addition, engineering considerations in the operation of fixed bed adsorption units and the main challenges associated to MOFs as adsorbents were also discussed.
Topics: Carbon Dioxide; Coal Mining; Metal-Organic Frameworks; Methane; Rivers
PubMed: 34111784
DOI: 10.1016/j.scitotenv.2021.148211 -
PloS One 2021There has been considerable interest in the use of red seaweed, and in particular Asparagopsis taxiformis, to increase production of cattle and to reduce greenhouse gas... (Meta-Analysis)
Meta-Analysis
There has been considerable interest in the use of red seaweed, and in particular Asparagopsis taxiformis, to increase production of cattle and to reduce greenhouse gas emissions. We hypothesized that feeding seaweed or seaweed derived products would increase beef or dairy cattle performance as indicated by average daily gain (ADG), feed efficiency measures, milk production, and milk constituents, and reduce methane emissions. We used meta-analytical methods to evaluate these hypotheses. A comprehensive search of Google Scholar, Pubmed and ISI Web of Science produced 14 experiments from which 23 comparisons of treatment effects could be evaluated. Red seaweed (Asparagopsis taxiformis) and brown seaweed (Ascophyllum nodosum) were the dominant seaweeds used. There were no effects of treatment on ADG or dry matter intake (DMI). While there was an increase in efficiency for feed to gain by 0.38 kg per kg [standardized mean difference (SMD) = 0.56; P = 0.001] on DerSimonian and Laird (D&L) evaluation, neither outcome was significant using the more rigorous robust regression analysis (P >0.06). The type of seaweed used was not a significant covariable for ADG and DMI, but A. nodosum fed cattle had lesser feed to gains efficiency compared to those fed A. taxiformis. Milk production was increased with treatment on weighted mean difference (WMD; 1.35 ± 0.44 kg/d; P <0.001); however, the SMD of 0.45 was not significant (P = 0.111). Extremely limited data suggest the possibility of increased percentages of milk fat (P = 0.040) and milk protein (P = 0.001) on (D&L) WMD evaluation. The limited data available indicate dietary supplementation with seaweed produced a significant and substantial reduction in methane yield by 5.28 ± 3.5 g/kg DMI (P = 0.003) on D&L WMD evaluation and a D&L SMD of -1.70 (P = 0.001); however, there was marked heterogeneity in the results (I2 > 80%). In one comparison, methane yield was reduced by 97%. We conclude that while there was evidence of potential for benefit from seaweed use to improve production and reduce methane yield more in vivo experiments are required to strengthen the evidence of effect and identify sources of heterogeneity in methane response, while practical applications and potential risks are evaluated for seaweed use.
Topics: Animal Feed; Animals; Cattle; Dairying; Diet; Methane; Seaweed
PubMed: 34252114
DOI: 10.1371/journal.pone.0249053 -
Environmental Science & Technology Dec 2023Under the Global Methane Pledge, Canada is developing oil and gas sector methane regulations targeting 75% reductions from 2012 levels by 2030. Without measured...
Under the Global Methane Pledge, Canada is developing oil and gas sector methane regulations targeting 75% reductions from 2012 levels by 2030. Without measured baselines and inventories, such policies are ultimately unverifiable and unenforceable. Using the major oil and gas producing province of Saskatchewan as a case study, we derive first-ever measurement-based methane inventories for the region and comprehensively model previous emissions back to the 2012 baseline. Although relative reductions of 23-69% have likely occurred, the dispersion of modeled possibilities and the high emissions from continuing production illustrate the limits of this approach as a meaningful policy metric. Moreover, nearly 90% of apparent reductions are explained by decreased production at heavy oil facilities, suggesting emissions have potential to rebound if production resumes. By contrast, derived measurement-based methane emissions intensities facilitate quantitative assessment and show that despite any past reductions, Saskatchewan's 0.41 ± 0.03 g/MJ intensity remains among the highest in North America. This highlights how relative reduction targets absent measured baselines and inventories are inherently futile and risk rewarding high emitters while obscuring ongoing mitigation potential. Ultimately, required global methane reductions will only be achieved by adopting objectively and independently verifiable emission metrics while measuring and tracking progress toward a net zero future.
Topics: Methane; Natural Gas; Air Pollutants; Medical Futility; Canada
PubMed: 38048428
DOI: 10.1021/acs.est.3c07722 -
GigaScience Jan 2022Mitigating the effects of global warming has become the main challenge for humanity in recent decades. Livestock farming contributes to greenhouse gas emissions, with an...
BACKGROUND
Mitigating the effects of global warming has become the main challenge for humanity in recent decades. Livestock farming contributes to greenhouse gas emissions, with an important output of methane from enteric fermentation processes, mostly in ruminants. Because ruminal microbiota is directly involved in digestive fermentation processes and methane biosynthesis, understanding the ecological relationships between rumen microorganisms and their active metabolic pathways is essential for reducing emissions. This study analysed whole rumen metagenome using long reads and considering its compositional nature in order to disentangle the role of rumen microbes in methane emissions.
RESULTS
The β-diversity analyses suggested a subtle association between methane production and overall microbiota composition (0.01 < R2 < 0.02). Differential abundance analysis identified 36 genera and 279 KEGGs as significantly associated with methane production (Padj < 0.05). Those genera associated with high methane production were Eukaryota from Alveolata and Fungi clades, while Bacteria were associated with low methane emissions. The genus-level association network showed 2 clusters grouping Eukaryota and Bacteria, respectively. Regarding microbial gene functions, 41 KEGGs were found to be differentially abundant between low- and high-emission animals and were mainly involved in metabolic pathways. No KEGGs included in the methane metabolism pathway (ko00680) were detected as associated with high methane emissions. The KEGG network showed 3 clusters grouping KEGGs associated with high emissions, low emissions, and not differentially abundant in either. A deeper analysis of the differentially abundant KEGGs revealed that genes related with anaerobic respiration through nitrate degradation were more abundant in low-emission animals.
CONCLUSIONS
Methane emissions are largely associated with the relative abundance of ciliates and fungi. The role of nitrate electron acceptors can be particularly important because this respiration mechanism directly competes with methanogenesis. Whole metagenome sequencing is necessary to jointly consider the relative abundance of Bacteria, Archaea, and Eukaryota in the statistical analyses. Nutritional and genetic strategies to reduce CH4 emissions should focus on reducing the relative abundance of Alveolata and Fungi in the rumen. This experiment has generated the largest ONT ruminal metagenomic dataset currently available.
Topics: Animals; Cattle; Fungi; Metagenome; Metagenomics; Methane; Rumen
PubMed: 35077540
DOI: 10.1093/gigascience/giab088 -
Waste Management (New York, N.Y.) May 2022A biocover system was established at Klintholm landfill in Denmark in 2009 to mitigate methane emissions, and the system exhibited high mitigation efficiency during the...
A biocover system was established at Klintholm landfill in Denmark in 2009 to mitigate methane emissions, and the system exhibited high mitigation efficiency during the first year after implementation. The biocover system was revisited in 2016/2017, and a series of field and laboratory tests were carried out to evaluate functionality about six years after establishment. Three field campaigns were executed in three different barometric pressure conditions, namely increasing, stable and decreasing. Local surface flux measurements and gas concentration profiles in the methane oxidation layer showed that barometric pressure changes had a significant effect on gas emission and methane oxidation. Elevated concentrations of oxygen were observed in the gas distribution layer, and field data showed that significant methane oxidation took place in this location. This finding was verified in laboratory-based methane oxidation incubation tests. Temperatures higher than ambient temperature were observed throughout the methane oxidation layer, with average temperatures ranging between 13 and 27 °C, even in the coldest month of the year. Field measurements showed that total methane emissions from the whole landfill cell were at the same level or lower than measurements performed in 2009/2010 after implementation of the biocover system, and laboratory tests showed methane oxidation potential approximately equal to former tests. In spite of an inhomogeneous distribution of landfill gas load to the methane oxidation layer, the performance of the biocover system had not declined over the 6-7 years since its establishment, even though no maintenance had been carried out in the intervening years.
Topics: Air Pollutants; Methane; Oxidation-Reduction; Refuse Disposal; Temperature; Waste Disposal Facilities
PubMed: 35525002
DOI: 10.1016/j.wasman.2022.04.034 -
Journal of Dairy Science May 2020This study aimed to identify interactions between state of lactation (dry or early lactating) and immune responder group (low, medium, or high) for energy metabolism...
This study aimed to identify interactions between state of lactation (dry or early lactating) and immune responder group (low, medium, or high) for energy metabolism traits as well as metabolic and immunological traits in dairy cows. In early lactation, when the energy priority of cows shifts toward the mammary gland, the energy available to be partitioned toward the immune system may differ among individuals. The equilibrium between energy supply from feed, digestion, and body reserve mobilization and energy expenditure with milk, immune system, methane, and heat production is delicate in this stage. Seventeen Holstein cows entering their second to fifth lactation were kept under comparable feeding, housing, and management conditions and were studied from 14 ± 6 d before calving to 11 ± 3 d after calving. Feed intake, milk yield, body condition, blood metabolites, and cortisol as well as gaseous exchange in respiration chambers were measured. The latter was used to quantify methane emission and to calculate resting metabolic rate and heat production. Subsets of blood leukocytes and peripheral blood mononuclear cells (PBMC) were monitored. Activation and proliferation of the PBMC in response to the mitogen phytohemagglutinin ante- and postpartum were assessed using the oxygen consumption rate (24-h cell culture assay) and the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) assay (72-h cell culture assay). Cows were classified based on the in vitro proliferative response of the PBMC measured postpartum in low (n = 6), medium (n = 5), and high (n = 6) responders. We found no interaction of state of lactation with responder group for feed intake, milk yield, efficiency, metabolic traits, and immune cell activation ante- and postpartum. However, after calving, low-responder cows produced less methane per unit of body weight and per unit of energy-corrected milk compared with the other cows. This might be indicative of a low rumen fermentation intensity. Low responders might therefore suffer from a lower availability of digestible energy in early lactation and not be able to sustain the shift from immune cell activation to proliferation. If so, the selection of environmentally friendly low-methane emitters could promote phenotypes with a compromised immune response in the critical early lactation.
Topics: Animals; Cattle; Cell Proliferation; Dairying; Female; Lactation; Lymphocytes; Methane
PubMed: 32147260
DOI: 10.3168/jds.2019-17584 -
Journal of Animal Science Jul 2022The contribution of greenhouse gas (GHG) emissions from ruminant production systems varies between countries and between regions within individual countries. The... (Review)
Review
The contribution of greenhouse gas (GHG) emissions from ruminant production systems varies between countries and between regions within individual countries. The appropriate quantification of GHG emissions, specifically methane (CH4), has raised questions about the correct reporting of GHG inventories and, perhaps more importantly, how best to mitigate CH4 emissions. This review documents existing methods and methodologies to measure and estimate CH4 emissions from ruminant animals and the manure produced therein over various scales and conditions. Measurements of CH4 have frequently been conducted in research settings using classical methodologies developed for bioenergetic purposes, such as gas exchange techniques (respiration chambers, headboxes). While very precise, these techniques are limited to research settings as they are expensive, labor-intensive, and applicable only to a few animals. Head-stalls, such as the GreenFeed system, have been used to measure expired CH4 for individual animals housed alone or in groups in confinement or grazing. This technique requires frequent animal visitation over the diurnal measurement period and an adequate number of collection days. The tracer gas technique can be used to measure CH4 from individual animals housed outdoors, as there is a need to ensure low background concentrations. Micrometeorological techniques (e.g., open-path lasers) can measure CH4 emissions over larger areas and many animals, but limitations exist, including the need to measure over more extended periods. Measurement of CH4 emissions from manure depends on the type of storage, animal housing, CH4 concentration inside and outside the boundaries of the area of interest, and ventilation rate, which is likely the variable that contributes the greatest to measurement uncertainty. For large-scale areas, aircraft, drones, and satellites have been used in association with the tracer flux method, inverse modeling, imagery, and LiDAR (Light Detection and Ranging), but research is lagging in validating these methods. Bottom-up approaches to estimating CH4 emissions rely on empirical or mechanistic modeling to quantify the contribution of individual sources (enteric and manure). In contrast, top-down approaches estimate the amount of CH4 in the atmosphere using spatial and temporal models to account for transportation from an emitter to an observation point. While these two estimation approaches rarely agree, they help identify knowledge gaps and research requirements in practice.
Topics: Animals; Eating; Greenhouse Gases; Manure; Methane; Ruminants
PubMed: 35657151
DOI: 10.1093/jas/skac197 -
Environmental Science & Technology Jan 2024Reducing emissions of the key greenhouse gas methane (CH) is increasingly highlighted as being important to mitigate climate change. Effective emission reductions...
Reducing emissions of the key greenhouse gas methane (CH) is increasingly highlighted as being important to mitigate climate change. Effective emission reductions require cost-effective ways to measure CH to detect sources and verify that mitigation efforts work. We present here a novel approach to measure methane at atmospheric concentrations by means of a low-cost electronic nose strategy where the readings of a few sensors are combined, leading to errors down to 33 ppb and coefficients of determination, , up to 0.91 for in situ measurements. Data from methane, temperature, humidity, and atmospheric pressure sensors were used in customized machine learning models to account for environmental cross-effects and quantify methane in the ppm-ppb range both in indoor and outdoor conditions. The electronic nose strategy was confirmed to be versatile with improved accuracy when more reference data were supplied to the quantification model. Our results pave the way toward the use of networks of low-cost sensor systems for the monitoring of greenhouse gases.
Topics: Air Pollutants; Methane; Electronic Nose; Greenhouse Gases; Climate Change; Environmental Monitoring
PubMed: 38126254
DOI: 10.1021/acs.est.3c06945