Nitrous oxide (N2O) is a potent greenhouse gas and the predominant ozone depleting substance. The only enzyme known to reduce N2O is the nitrous oxide reductase, encoded by the nosZ gene, which is ...present among bacteria and archaea capable of either complete denitrification or only N2O reduction to di-nitrogen gas. To determine whether the occurrence of nosZ, being a proxy for the trait N2O reduction, differed among taxonomic groups, preferred habitats or organisms having either NirK or NirS nitrite reductases encoded by the nirK and nirS genes, respectively, 652 microbial genomes across 18 phyla were compared. Furthermore, the association of different co-occurrence patterns with enzymes reducing nitric oxide to N2O encoded by nor genes was examined. We observed that co-occurrence patterns of denitrification genes were not randomly distributed across taxa, as specific patterns were found to be more dominant or absent than expected within different taxonomic groups. The nosZ gene had a significantly higher frequency of co-occurrence with nirS than with nirK and the presence or absence of a nor gene largely explained this pattern, as nirS almost always co-occurred with nor. This suggests that nirS type denitrifiers are more likely to be capable of complete denitrification and thus contribute less to N2O emissions than nirK type denitrifiers under favorable environmental conditions. Comparative phylogenetic analysis indicated a greater degree of shared evolutionary history between nosZ and nirS. However 30% of the organisms with nosZ did not possess either nir gene, with several of these also lacking nor, suggesting a potentially important role in N2O reduction. Co-occurrence patterns were also non-randomly distributed amongst preferred habitat categories, with several habitats showing significant differences in the frequencies of nirS and nirK type denitrifiers. These results demonstrate that the denitrification pathway is highly modular, thus underpinning the importance of community structure for N2O emissions.
Genomics and Ecology of Novel N2O-Reducing Microorganisms Hallin, Sara; Philippot, Laurent; Löffler, Frank E. ...
Trends in microbiology,
January 2018, 2018-01-00, 20180101, 2018, 2018-01-01, Letnik:
26, Številka:
1
Journal Article
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Microorganisms with the capacity to reduce the greenhouse gas nitrous oxide (N2O) to harmless dinitrogen gas are receiving increased attention due to increasing N2O emissions (and our need to ...mitigate climate change) and to recent discoveries of novel N2O-reducing bacteria and archaea. The diversity of denitrifying and nondenitrifying microorganisms with capacity for N2O reduction was recently shown to be greater than previously expected. A formerly overlooked group (clade II) in the environment include a large fraction of nondenitrifying N2O reducers, which could be N2O sinks without major contribution to N2O formation. We review the recent advances about fundamental understanding of the genomics, physiology, and ecology of N2O reducers and the importance of these findings for curbing N2O emissions.
N2O is produced in several microbial processes, but N2O reduction is limited to a single process catalyzed by the N2O reductase present among taxonomically diverse bacteria and archaea. This enzyme is used for energy conservation through anaerobic respiration, detoxification, or removal of excess electrons.
The N2O reductase has evolved into two lineages, clade I and the recently described clade II. Surveys indicate that clade II N2O reductase (NosZ) is abundant in many biomes.
Genome analyses and culture-based studies suggest that the physiology of N2O reduction differs between the clades. Evidence from community ecology supports niche differentiation of organisms with either type of N2O reductase, and within the two clades.
Identifying factors that drive physiological and ecological responses of N2O-reducing communities could lead to effective and innovative strategies to curb N2O emissions.
There is growing interest in the use of algorithms to objectively compare near-UV spectra of protein biopharmaceuticals in a regulated environment. Such use will require that the methods be ...validated, with International Conference on the Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) currently being the key document. A key aspect of such validation is to understand how robust the method is to experimental variation. Noise-free simulated spectra, obtained by fitting multiple Gaussian peaks to experimental data obtained from a pharmaceutical protein, were used to assess the robustness of several algorithms in response to spectral data “imperfections”. Sources and magnitudes of these imperfections were derived from published inter-laboratory studies. Spectral noise, wavelength calibration errors, intensity variation, and spectral offset errors were “titrated” into the noise-free simulated spectrum and imperfect data sets were compared with the simulated data using a variety of published algorithms, including Pearson, Prestrelski, and derivative correlation algorithms, and spectral overlap, spectral difference and weighted spectral difference methods, to understand how robust outputs are to imperfect data. Algorithm was assessed by comparing their sensitivity to imperfect data against the pairwise statistical variation between 20 replicate spectra.
Graphical Abstract
Abstract Background Heroin use and overdose deaths have increased in recent years. Emerging information suggests this is the result of increases in nonmedical use of opioid pain relievers and ...nonmedical users transitioning to heroin use. Understanding this relationship is critically important for the development of public health interventions. Methods Combined data from the 2002–2004 National Surveys on Drug Use and Health were compared to the 2008–2010 surveys to examine patterns of heroin use and risk behaviors among past year nonmedical users of opioid pain relievers. Results Between 2002–2004 and 2008–2010, past year heroin use increased among people reporting past year nonmedical use (PYNMU) of opioid pain relievers ( p < 0.01), but not among those reporting no PYNMU. Frequent nonmedical users – people reporting 100–365 days of PYNMU – had the highest rate of past year heroin use and were at increased risk for ever injecting heroin (aOR 4.3, 95% CI 2.5–7.3) and past year heroin abuse or dependence (aOR 7.8, 95% CI 4.7–12.8) compared to infrequent nonmedical users (1–29 days of PYNMU). In 2008–2010, 82.6% of frequent nonmedical users who used heroin in the past year reported nonmedical use of opioid pain relievers prior to heroin initiation compared to 64.1% in 2002–2004. Conclusions Heroin use among nonmedical users of opioid pain relievers increased between 2002–2004 and 2008–2010, with most reporting nonmedical use of opioid pain relievers before initiating heroin. Interventions to prevent nonmedical use of these drugs are needed and should focus on high-risk groups such as frequent nonmedical users of opioids.
Microbial communities transform nitrogen (N) compounds, thereby regulating the availability of N in soil. The N cycle is defined by interacting microbial functional groups, as inorganic N‐products ...formed in one process are the substrate in one or several other processes. The nitrification pathway is often a two‐step process in which bacterial or archaeal communities oxidize ammonia to nitrite, and bacterial communities further oxidize nitrite to nitrate. Little is known about the significance of interactions between ammonia‐oxidizing bacteria (AOB) and archaea (AOA) and nitrite‐oxidizing bacterial communities (NOB) in determining the spatial variation of overall nitrifier community structure. We hypothesize that nonrandom associations exist between different AO and NOB lineages that, along with edaphic factors, shape field‐scale spatial patterns of nitrifying communities. To address this, we sequenced and quantified the abundance of AOA, AOB, and Nitrospira and Nitrobacter NOB communities across a 44‐hectare site with agricultural fields. The abundance of Nitrobacter communities was significantly associated only with AOB abundance, while that of Nitrospira was correlated to AOA. Network analysis and geostatistical modelling revealed distinct modules of co‐occurring AO and NOB groups occupying disparate areas, with each module dominated by different lineages and associated with different edaphic factors. Local communities were characterized by a high proportion of module‐connecting versus module‐hub nodes, indicating that nitrifier assemblages in these soils are shaped by fluctuating conditions. Overall, our results demonstrate the utility of network analysis in accounting for potential biotic interactions that define the niche space of nitrifying communities at scales compatible to soil management.
Since the time of the industrial revolution, the atmospheric CO2 concentration has risen by nearly 35 % to its current level of 383 ppm. The increased carbon dioxide concentration in the atmosphere ...has been suggested to be a leading contributor to global climate change. To slow the increase, reductions in anthropogenic CO2 emissions are necessary. Large emission point sources, such as fossil‐fuel‐based power generation facilities, are the first targets for these reductions. A benchmark, mature technology for the separation of dilute CO2 from gas streams is via absorption with aqueous amines. However, the use of solid adsorbents is now being widely considered as an alternative, potentially less‐energy‐intensive separation technology. This Review describes the CO2 adsorption behavior of several different classes of solid carbon dioxide adsorbents, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic–inorganic hybrids, and metal‐organic frameworks. These adsorbents are evaluated in terms of their equilibrium CO2 capacities as well as other important parameters such as adsorption–desorption kinetics, operating windows, stability, and regenerability. The scope of currently available CO2 adsorbents and their critical properties that will ultimately affect their incorporation into large‐scale separation processes is presented.
Getting the point: As concern over the rise in atmospheric CO2 concentration has increased, recent research efforts have focused on capturing CO2 from large anthropogenic point sources. Many solid adsorbent classes, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic–inorganic hybrids, and MOFs, have been considered as alternatives to the current benchmark aqueous amine absorption technology for CO2 capture.
We estimated national and state trends in opioid agonist medication-assisted treatment (OA-MAT) need and capacity to identify gaps and inform policy decisions.
We generated national and state rates ...of past-year opioid abuse or dependence, maximum potential buprenorphine treatment capacity, number of patients receiving methadone from opioid treatment programs (OTPs), and the percentage of OTPs operating at 80% capacity or more using Substance Abuse and Mental Health Services Administration data.
Nationally, in 2012, the rate of opioid abuse or dependence was 891.8 per 100 000 people aged 12 years or older compared with national rates of maximum potential buprenorphine treatment capacity and patients receiving methadone in OTPs of, respectively, 420.3 and 119.9. Among states and the District of Columbia, 96% had opioid abuse or dependence rates higher than their buprenorphine treatment capacity rates; 37% had a gap of at least 5 per 1000 people. Thirty-eight states (77.6%) reported at least 75% of their OTPs were operating at 80% capacity or more.
Significant gaps between treatment need and capacity exist at the state and national levels. Strategies to increase the number of OA-MAT providers are needed.
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