Methylotrophic methanogens everywhere — physiology and ecology of novel players in global methane cycling

2019 ◽  
Vol 47 (6) ◽  
pp. 1895-1907 ◽  
Author(s):  
Andrea Söllinger ◽  
Tim Urich

Research on methanogenic Archaea has experienced a revival, with many novel lineages of methanogens recently being found through cultivation and suggested via metagenomics approaches, respectively. Most of these lineages comprise Archaea (potentially) capable of methanogenesis from methylated compounds, a pathway that had previously received comparably little attention. In this review, we provide an overview of these new lineages with a focus on the Methanomassiliicoccales. These lack the Wood–Ljungdahl pathway and employ a hydrogen-dependent methylotrophic methanogenesis pathway fundamentally different from traditional methylotrophic methanogens. Several archaeal candidate lineages identified through metagenomics, such as the Ca. Verstraetearchaeota and Ca. Methanofastidiosa, encode genes for a methylotrophic methanogenesis pathway similar to the Methanomassiliicoccales. Thus, the latter are emerging as a model system for physiological, biochemical and ecological studies of hydrogen-dependent methylotrophic methanogens. Methanomassiliicoccales occur in a large variety of anoxic habitats including wetlands and animal intestinal tracts, i.e. in the major natural and anthropogenic sources of methane emissions, respectively. Especially in ruminant animals, they likely are among the major methane producers. Taken together, (hydrogen-dependent) methylotrophic methanogens are much more diverse and widespread than previously thought. Considering the role of methane as potent greenhouse gas, resolving the methanogenic nature of a broad range of putative novel methylotrophic methanogens and assessing their role in methane emitting environments are pressing issues for future research on methanogens.

mSystems ◽  
2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Andrea Söllinger ◽  
Alexander Tøsdal Tveit ◽  
Morten Poulsen ◽  
Samantha Joan Noel ◽  
Mia Bengtsson ◽  
...  

ABSTRACTRuminant livestock is a major source of the potent greenhouse gas methane. The complex rumen microbiome, consisting of bacteria, archaea, and microbial eukaryotes, facilitates anaerobic plant biomass degradation in the cow rumen, leading to methane emissions. Using an integrated approach combining multidomain quantitative metatranscriptomics with gas and volatile fatty acid (VFA) profiling, we aimed at obtaining the most comprehensive picture of the active rumen microbiome during feed degradation to date. Bacterial, archaeal, and eukaryotic biomass, but also methane emissions and VFA concentrations, increased drastically within an hour after feed intake. mRNA profiling revealed a dynamic response of carbohydrate-active enzyme transcripts, transcripts involved in VFA production and methanogenesis. While the relative abundances of functional transcripts did not mirror observed processes, such as methane emissions, transformation to mRNA abundance per gram of rumen fluid echoed ruminant processes. The microbiome composition was highly individual, with, e.g., ciliate,Neocallimastigaceae,Prevotellaceae,Succinivibrionaceae, andFibrobacteraceaeabundances differing between cows. Microbiome individuality was accompanied by inter- and intradomain multifunctional redundancy among microbiome members during feed degradation. This likely enabled the robust performance of the anaerobic degradation process in each rumen.Neocallimastigaceaeand ciliates contributed an unexpectedly large share of transcripts for cellulose- and hemicellulose-degrading enzymes, respectively. Methyl-reducing but not CO2-reducing methanogens were positively correlated with methane emissions. WhileMethanomassiliicoccalesswitched from methanol to methylamines as electron acceptors,Methanosphaerabecame the dominating methanol-reducing methanogen. This study for the first time linked rumen meta-omics with processes and enabled holistic insights into the contribution of all microbiome members to feed degradation.IMPORTANCERuminant animals, such as cows, live in a tight symbiotic association with microorganisms, allowing them to feed on otherwise indigestible plant biomass as food sources. Methane is produced as an end product of the anaerobic feed degradation in ruminants and is emitted to the atmosphere, making ruminant animals among the major anthropogenic sources of the potent greenhouse gas methane. Using newly developed quantitative metatranscriptomics for holistic microbiome analysis, we here identified bacterial, archaeal, and eukaryotic key players and the short-term dynamics of the rumen microbiome during anaerobic plant biomass degradation and subsequent methane emissions. These novel insights might pave the way for novel ecologically and economically sustainable methane mitigation strategies, much needed in times of global climate change.


2021 ◽  
Vol 12 ◽  
Author(s):  
Danae Zeballos-Gross ◽  
Zulma Rojas-Sereno ◽  
Marília Salgado-Caxito ◽  
Patricia Poeta ◽  
Carmen Torres ◽  
...  

The role of wildlife with long-range dispersal such as gulls in the global dissemination of antimicrobial resistance (AMR) across natural and anthropogenic aquatic environments remains poorly understood. Antibiotic-resistant bacteria have been detected in resident and migratory gulls worldwide for more than a decade, suggesting gulls as either sentinels of AMR pollution from anthropogenic sources or independent reservoirs that could maintain and disperse AMR across aquatic environments. However, confirming either of these roles remains challenging and incomplete. In this review, we present current knowledge on the geographic regions where AMR has been detected in gulls, the molecular characterization of resistance genes, and the evidence supporting the capacity of gulls to disperse AMR across regions or countries. We identify several limitations of current research to assess the role of gulls in the spread of AMR including most studies not identifying the source of AMR, few studies comparing bacteria isolated in gulls with other wild or domestic species, and almost no study performing longitudinal sampling over a large period of time to assess the maintenance and dispersion of AMR by gulls within and across regions. We suggest future research required to confirm the role of gulls in the global dispersion of AMR including the standardization of sampling protocols, longitudinal sampling using advanced satellite tracking, and whole-genome sequencing typing. Finally, we discuss the public health implications of the spread of AMR by gulls and potential solutions to limit its spread in aquatic environments.


mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Zachary Liechty ◽  
Christian Santos-Medellín ◽  
Joseph Edwards ◽  
Bao Nguyen ◽  
David Mikhail ◽  
...  

ABSTRACT Rice cultivation worldwide accounts for ∼7 to 17% of global methane emissions. Methane cycling in rice paddies is a microbial process not only involving methane producers (methanogens) and methane metabolizers (methanotrophs) but also other microbial taxa that affect upstream processes related to methane metabolism. Rice cultivars vary in their rates of methane emissions, but the influence of rice genotypes on methane cycling microbiota has been poorly characterized. Here, we profiled the rhizosphere, rhizoplane, and endosphere microbiomes of a high-methane-emitting cultivar (Sabine) and a low-methane-emitting cultivar (CLXL745) throughout the growing season to identify variations in the archaeal and bacterial communities relating to methane emissions. The rhizosphere of the high-emitting cultivar was enriched in methanogens compared to that in the low emitter, whereas the relative abundances of methanotrophs between the cultivars were not significantly different. Further analysis of cultivar-sensitive taxa identified families enriched in the high emitter that are associated with methanogenesis-related processes. The high emitter had greater relative abundances of sulfate-reducing and iron-reducing taxa which peak earlier in the season than methanogens and are necessary to lower soil oxidation reduction potential before methanogenesis can occur. The high emitter also had a greater abundance of fermentative taxa which produce methanogenesis precursors (acetate, CO2, and H2). Furthermore, the high emitter was enriched in taxa related to acetogenesis which compete with methanogens for CO2 and H2. These taxa were enriched in a spatio-specific manner and reveal a complex network of microbial interactions on which plant genotype-dependent factors can act to affect methanogenesis and methane emissions. IMPORTANCE Rice cultivation is a major source of anthropogenic emissions of methane, a greenhouse gas with a potentially severe impact on climate change. Emission variation between rice cultivars suggests the feasibility of breeding low-emission rice, but there is a limited understanding of how genotypes affect the microbiota involved in methane cycling. Here, we show that the root microbiome of the high-emitting cultivar is enriched both in methanogens and in taxa associated with fermentation, iron, and sulfate reduction and acetogenesis, processes that support methanogenesis. Understanding how cultivars affect microbes with methanogenesis-related functions is vital for understanding the genetic basis for methane emission in rice and can aid in the development of breeding programs that reduce the environmental impact of rice cultivation.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2116 ◽  
Author(s):  
Danielle T. Fradet ◽  
Patricia L. Tavormina ◽  
Victoria J. Orphan

Proteobacteria capable of converting the greenhouse gas methane to biomass, energy, and carbon dioxide represent a small but important sink in global methane inventories. Currently, 23 genera of methane oxidizing (methanotrophic) proteobacteria have been described, although many are represented by only a single validly described species. Here we describe a new methanotrophic isolate that shares phenotypic characteristics and phylogenetic relatedness with the marine methanotrophMethylomarinum vadi. However, the new isolate derives from a terrestrial saline mud pot at the northern terminus of the Eastern Pacific Rise (EPR). This new cultivar expands our knowledge of the ecology ofMethylomarinum, ultimately towards a fuller understanding of the role of this genus in global methane cycling.


2011 ◽  
Vol 8 (5) ◽  
pp. 1267-1278 ◽  
Author(s):  
F. J. W. Parmentier ◽  
J. van Huissteden ◽  
N. Kip ◽  
H. J. M. Op den Camp ◽  
M. S. M. Jetten ◽  
...  

Abstract. The role of the microbial processes governing methane emissions from tundra ecosystems is receiving increasing attention. Recently, cooperation between methanotrophic bacteria and submerged Sphagnum was shown to reduce methane emissions but also to supply CO2 for photosynthesis for the plant. Although this process was shown to be important in the laboratory, the differences that exist in methane emissions from inundated vegetation types with or without Sphagnum in the field have not been linked to these bacteria before. In this study, chamber flux measurements, an incubation study and a process model were used to investigate the drivers and controls on the relative difference in methane emissions between a submerged Sphagnum/sedge vegetation type and an inundated sedge vegetation type without Sphagnum. It was found that methane emissions in the Sphagnum-dominated vegetation type were 50 % lower than in the vegetation type without Sphagnum. A model sensitivity analysis showed that these differences could not sufficiently be explained by differences in methane production and plant transport. The model, combined with an incubation study, indicated that methane oxidation by endophytic bacteria, living in cooperation with submerged Sphagnum, plays a significant role in methane cycling at this site. This result is important for spatial upscaling as oxidation by these bacteria is likely involved in 15 % of the net methane emissions at this tundra site. Our findings support the notion that methane-oxidizing bacteria are an important factor in understanding the processes behind methane emissions in tundra.


Author(s):  
Hatice Nur Kılıç ◽  
Mustafa Boga

The methods applied for yield increases per unit animal are also progressing rapidly, along with the rapid progress of agricultural and animal production in parallel with the rapidly developing population and the food demand. The increase in animal products increases the environmental impacts per unit of animal product. With the increase in animal wastes in recent years, greenhouse gas emissions have increased even more, thus negatively affecting the environment and animal health. In order to prevent this negative effect, sustainable methods and strategic measures related to animal feeding and care are important in order to reduce the emission of harmful greenhouse gases. Methane, which is the second most important greenhouse gas, is found in large amounts in the atmosphere as a molecule, the accumulation of this gas in the atmosphere more than CO₂ increases the interest in this subject. Different practices related to the nutrition of ruminant animals (use of feed additives, feeding strategies) in order to optimize rumen conditions and increase productivity per unit animal is a developing area. Sharing this information with animal breeders will also benefit the environment, and therefore human and animal health, in terms of reducing both methane and nitrogen emissions. In ruminant animals, it can cause a loss of 2-12% of the gross energy taken with the feed so that the methane gas can be removed from the body. There are many studies on feeding to reduce nitrogen losses in faeces and urine, which cause methane emissions for ruminants, and many of these studies still do not reach a permanent conclusion. The reduction in enteric CH₄ emissions to be made must be tailored to the specific needs of farmers and livestock, and to be cost-effective. In our study, it is aimed to compile animal feeding strategies and reduction of methane emissions under different conditions.


2018 ◽  
Author(s):  
Alistair Grinham ◽  
Simon Albert ◽  
Nathaniel Deering ◽  
Matthew Dunbabin ◽  
David Bastviken ◽  
...  

Abstract. Emissions from flooded land represent a direct source of anthropogenic greenhouse gas emissions. Methane emissions from large, artificial water bodies have previously been considered, with numerous studies assessing emission rates and relatively simple procedures available to determine their surface area and generate upscaled emissions estimates. In contrast, the role of small artificial water bodies (ponds) is very poorly quantified, and estimation of emissions is constrained both by a lack of data on their spatial extent, and a scarcity of direct flux measurements. In this study, we quantified the total surface area of water bodies


Author(s):  
G.C. Waghorn ◽  
M.H. Tavendale ◽  
D.R. Woodfield

Methane production has been measured from lambs fed contrasting forages. This work has been driven by the need to reduce greenhouse gas emissions from agriculture and to determine energy losses to methane from contrasting diets. Young ram lambs were fed either fresh ryegrass/white clover pasture, lucerne (also pelleted lucerne), sulla, chicory, red clover, Lotus pedunculatus (lotus) and mixtures of sulla and lucerne, sulla and chicory and chicory with red clover. The effects of condensed tannin (CT) in lotus on methane production were also measured. The trials were carried out indoors with sheep held in metabolism crates to enable an accurate measurement of intake and digestibility as well as methane production. Principal findings were a two-fold range in emissions from 11.5g CH4/kg dry matter intake (DMI) with lotus to 25.7g CH4/kg DMI with pasture and a 16% reduction in methane production due to the CT in lotus. This range in emissions from good quality forages represents a loss of about 7-11% of metabolisable energy and presents a clear direction for future research to better utilise the feeding value of pastures and reduce greenhouse gas (GHG) emissions from agriculture. High quality perennial forages should be used where practical, and researchers need to identify plant parameters responsible for the variation in methane emissions. Research must focus on rapid passage of digesta through the rumen of grazing animals and will involve manipulation of the fibre content of grasses. Introduction of CT into diets is a likely target to reduce methane production. Improving the rapidly digestible constituents of forages is another opportunity, but difficult to target. Keywords: condensed tannins, forage quality, forages, greenhouse gases, methane emissions, sheep


2017 ◽  
Vol 16 (3) ◽  
pp. 155-159 ◽  
Author(s):  
Peizhen Sun ◽  
Jennifer J. Chen ◽  
Hongyan Jiang

Abstract. This study investigated the mediating role of coping humor in the relationship between emotional intelligence (EI) and job satisfaction. Participants were 398 primary school teachers in China, who completed the Wong Law Emotional Intelligence Scale, Coping Humor Scale, and Overall Job Satisfaction Scale. Results showed that coping humor was a significant mediator between EI and job satisfaction. A further examination revealed, however, that coping humor only mediated two sub-dimensions of EI (use of emotion and regulation of emotion) and job satisfaction. Implications for future research and limitations of the study are discussed.


2019 ◽  
Vol 19 (2) ◽  
pp. 23-38
Author(s):  
Daniel Hummel

A small but growing area of public administration scholarship appreciates the influence of religious values on various aspects of government. This appreciation parallels a growing interest in comparative public administration and indigenized forms of government which recognizes the role of culture in different approaches to government. This article is at the crossroads of these two trends while also considering a very salient region, the Islamic world. The Islamic world is uniquely religious, which makes this discussion even more relevant, as the nations that represent them strive towards legitimacy and stability. The history and core values of Islam need to be considered as they pertain to systems of government that are widely accepted by the people. In essence, this is being done in many countries across the Islamic world, providing fertile grounds for public administration research from a comparative perspective. This paper explores these possibilities for future research on this topic.


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