Résumé
RESUMEN El objetivo del estudio fue la caracterización productiva y de emisiones modeladas de gases de efecto invernadero (GEI) en 61 sistemas lecheros localizados en cinco regiones de Honduras. Durante las fases inicial (FI) y final (FF), con encuestas aplicadas individualmente a los productores, se identificaron aspectos técnicos y de productividad. Variables numéricas expresadas en Microsoft Excel ® permitieron, con el modelo FAO de evaluación ambiental de la ganadería global-interactivo (GLEAM-i, por sus siglas en inglés) de ciclo de vida, estimar emisiones anuales de metano (CH4), óxido nitroso (N2O) y dióxido de carbono (CO2) en cada finca. Cálculos intermedios (GEI/animal) fueron derivados de la modelización GLEAM-i en Excel®. Durante la FI las fincas conjuntamente emitieron 25.038 t CO2 equivalente (CO2-eq), mientras que dichas emisiones fueron 10,5% menores en la FF. Emisiones de GEI/animal (2,85 ± 0,08 t CO2-eq) y de GEI/kg de proteína láctea (96,91 ± 4,50 kg CO2-eq) durante la FI fue-ron 13 y 21% menores en la FF, respectivamente. Valores de 52,82 ± 1,64 (CH4) y 2,66 ± 0,10 (N2O) kg/animal en la FI fueron 13% y 17% menores en la FF, respectivamente. La región Centro-Sur-Oriente emitió la menor cantidad de CH4 (42,95 ± 2,37 kg/animal) y N2O (1,82 ± 0,15 kg/animal, mientras las regiones Occidente y Norte experimentaron una reducción del 27% en GEI/kg proteína láctea entre la FI y FF. Se concluyó que la metodologia usada identificó los impactos productivos y medioambientales, derivados de alternativas técnicas implementadas en sistemas de producción lechera de Honduras.
ABSTRACT The study aimed to characterize production dynamics and greenhouse gas (GHG) emissions from 61 dairy farms in five regions in Honduras. Farm data were collected through individual surveys during the initial and final phases (IP; FP). Using Microsoft Excel, data was incorporated into the global livestock environmental assessment model-interactive (GLEAM-i, FAO) life cycle framework to estimate annual emissions of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) at the farm system level. Animal emissions (GHG/animal) were derived in Excel® from the GLEAM-i predictions. Together, farms during the IP emitted 25.038 t CO2 equivalent (CO2-eq) while these emissions were 10,5% lower in the FP. Emissions of GHG/animal (2,85 ± 0,08 t CO2-eq) and GHG/kg of milk protein (96,91 ± 4,50 kg CO2-eq) during the IP were 13% and 21% lower in the FP, respectively. Methane and N2O emission values (52,82 ± 1,64 vs. 2,66 ± 0,10 kg/animal) were 13% and 17% higher in the IP than in FP. The South-Central region emitted the lowest amount of CH4 and N2O (42,95 ± 2,37 kg/animal vs. 1,82 ± 0,15 kg/animal) while 27% lower GHG/kg milk protein was observed between the IP and FP of the Western and Northern regions. It was concluded that the used methodology identified productive and environmental impacts derived from implemented technical interventions in dairy production systems in Honduras.
Sujets)
Animaux , Industrie de la Viande , Industrie laitière , Paspalum , Diagnostic , Environnement , Gaz à effet de serre , Dioxyde de carbone , Production Alimentaire , Rendement , Fermentation , Méthane , Protoxyde d'azoteRésumé
Aerobic methane oxidizing bacteria (methanotrophs) can use methane as carbon source and energy source, eliminating 10%-20% of global methane. Methanotrophs can also effectively synthesize valuable methane-derived products. This article introduced the methane oxidizing mechanism of methanotrophs, and summarized the practical application and research hotspots of methanotrophs in the field of methane emission reduction in the landfill, ventilation air methane mitigation in coal mines, valuable chemicals biosynthesis, as well as oil and gas reservoir exploration. Main factors influencing the pollutant removal and the biosynthesis efficiency in various applications were also discussed. Based on the study of large-scale cultivation of methanotrophs, some measures to benefit the application and promotion of aerobic methane oxidizing biotechnology were proposed. This includes investigating the effect of intermediate metabolites on methanotrophs activity and population structure, and exploiting economical and efficient alternative culture media and culture techniques.
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Biotechnologie , Carbone , Milieux de culture/composition chimique , Méthane/métabolisme , Methylococcaceae/métabolisme , OxydoréductionRésumé
Landfill is one of the important sources of carbon tetrachloride (CT) pollution, and it is important to understand the degradation mechanism of CT in landfill cover for better control. In this study, a simulated landfill cover system was set up, and the biotransformation mechanism of CT and the associated micro-ecology were investigated. The results showed that three stable functional zones along the depth, i.e., aerobic zone (0-15 cm), anoxic zone (15-45 cm) and anaerobic zone (> 45 cm), were generated because of long-term biological oxidation in landfill cover. There were significant differences in redox condition and microbial community structure in each zone, which provided microbial resources and favorable conditions for CT degradation. The results of biodegradation indicated that dechlorination of CT produced chloroform (CF), dichloromethane (DCM) and Cl- in anaerobic and anoxic zones. The highest concentration of dechlorination products occurred at 30 cm, which were degraded rapidly in aerobic zone. In addition, CT degradation rate was 13.2-103.6 μg/(m2·d), which decreased with the increase of landfill gas flux. The analysis of diversity sequencing revealed that Mesorhizobium, Thiobacillus and Intrasporangium were potential CT-degraders in aerobic, anaerobic and anoxic zone, respectively. Moreover, six species of dechlorination bacteria and eighteen species of methanotrophs were also responsible for anaerobic transformation of CT and aerobic degradation of CF and DCM, respectively. Interestingly, anaerobic dechlorination and aerobic transformation occurred simultaneously in the anoxic zone in landfill cover. Furthermore, analysis of degradation mechanism suggested that generation of stable anaerobic-anoxic-aerobic zone by regulation was very important for the harmless removal of full halogenated hydrocarbon in vadose zone, and the increase of anoxic zone scale enhanced their removal. These results provide theoretical guidance for the removal of chlorinated pollutants in landfills.
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Bactéries/métabolisme , Dépollution biologique de l'environnement , Tétrachloro-méthane/métabolisme , Méthane/métabolisme , Installations d'élimination des déchetsRésumé
In this study, voltage was used as a disturbance factor to investigate the relationship between microbial community and methane (CH4) production flux in a microbial electrolytic cell coupled anaerobic digestion (MEC-AD). Metabolic flux analysis (MFA) was used to explore the relationship between the CH4 metabolic flux produced and the microbes. The results showed that both methane production flux and hydrogen production flux changed significantly upon voltage disturbance, while the voltage disturbance had little effect on acetic acid production flux. The maximum CH4 production flux under 0.6 V disturbance was 0.522±0.051, which increased by 77% and 32%, respectively, compared with that of the control group under 1.0 V (0.295±0.013) and under 1.4 V (0.395±0.029). In addition, an average of 15.7%±2.9% of H2 (flux) was used to reduce CO2 to produce CH4 and acetic acid, and an average of 27.7%±6.9% of acetic acid (flux) was converted to CH4. Moreover, the abundance of Lachnospiraceae significantly affected the flux of acetic acid. The flux of CH4 production is positively correlated with the abundances of Petrimonas, Syntrophomonas, Blvii28, and Acinetobacter, and negatively correlated with the abundances of Tuzzerella and Sphaerochaeta. The species that affected the flux of H2 and CH4 were similar, mostly belonging to Bacteroides, Clostridium, Pseudomonas and Firmicutes. Furthermore, the interspecies interaction is also an important factor affecting the MEC-AD methanogenesis flux.
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Acétates , Anaérobiose , Bioréacteurs , Électrolyse , MéthaneRésumé
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.
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Dioxyde de carbone/analyse , Autopsie , Chromatographie gazeuse-spectrométrie de masse , Méthane/analyse , AzoteRésumé
One-carbon compounds such as methanol and methane are cheap and readily available feedstocks for biomanufacturing. Oxidation of methanol to formaldehyde catalyzed by methanol dehydrogenase (MDH) is a key step of microbial one-carbon metabolism. A variety of MDHs that depend on different co-factors and possess different enzymatic properties have been discovered from native methylotrophs. Nicotinamide adenine dinucleotide (NAD)-dependent MDHs are widely used in constructing synthetic methylotrophs, whereas this type of MDH usually suffers from low methanol oxidation activity and low affinity to methanol. Consequently, methanol oxidation is considered as a rate-limiting step of methanol metabolism in synthetic methylotrophs. To accelerate methanol oxidation, thereby improving the methanol utilization efficiency of synthetic methylotrophs, massive researches have focused on discovery and engineering of MDHs. In this review, we summarize the ongoing efforts to discover, characterize, and engineer various types of MDHs as well as the applications of MDHs in synthetic methylotrophs. Directed evolution of MDH and construction of multi-enzyme complexes are described in detail. In the future prospective part, we discuss the potential strategies of growth-coupled protein evolution and rational protein design for acquisition of superior MDHs.
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Alcohol oxidoreductases/génétique , Carbone , Méthane , MéthanolRésumé
Due to abundant availability of shale gas and biogas, methane has been considered as one of the most potential carbon sources for industrial biotechnology. Methanotrophs carrying the native methane monooxygenase are capable of using methane as a sole energy and carbon source, which provides a novel strategy for reducing greenhouse gas emission and substituting edible substrates used in bioconversion processes. With the rapid development of genetic engineering tools and biosynthesis techniques, various strategies for improving the efficiency of methane bioconversion have been achieved to produce a variety of commodity bio-based products. Herein, we summarize several important aspects related with methane utilization and metabolic engineering of methanotrophs, including the modification of methane oxidation pathways, the construction of efficient cell factories, and biosynthesis of chemicals and fuels. Finally, the prospects and challenges of the future development of methane bioconversion are also discussed.
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Biocarburants , Biotechnologie , Génie métabolique , Méthane , OxydoréductionRésumé
The facultative anaerobic and strict anaerobic microorganisms enriched and acclimated during the anaerobic digestion process are crucial for the efficiency of the anaerobic digestion system. Most of the problems encountered during running anaerobic digestion processes could be effectively improved via stimulation of microbial metabolic activity. Benefited from the rapid development of microbiome techniques, deeper insights into the microbial diversity in anaerobic digestion systems, e.g. the microbe-microbe interactions and microbe-environment interactions, have been gained. A complex and intricate metabolic network exists in the anaerobic digestion system of solid organic wastes. However, little is known about these interactions and the underlying mechanisms. This review briefly summarized the representative interactions between microbial communities during anaerobic digestion process discovered to date. In addition, typical issues encountered during the anaerobic digestion of solid organic wastes and how microbes can tackle and alleviate these issues were discussed. Finally, future priorities on microbiome research were proposed based on present contribution of microbiome analysis in anaerobic digestion system.
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Anaérobiose , Bioréacteurs , Méthane , Interactions microbiennes , Microbiote , Déchets solidesRésumé
Methanogens are unique microorganisms for methane production and the main contributor of the biogenic methane in atmosphere. Methyl-coenzyme M reductase (Mcr) catalyzes the last step of methane production in methanogenesis and the first step of methane activation in anaerobic oxidation of methane. The genes encoding this enzyme are highly conserved and are widely used as a marker in the identification and phylogenetic study of archaea. There has been a longstanding interest in its unique cofactor F430 and the underpinning mechanisms of enzymatic cleavage of alkane C-H bond. The recent breakthroughs of high-resolution protein and catalytic-transition-state structures further advanced the structure-function study of Mcr. In particular, the recent discovery of methyl-coenzyme M reductase-like (Mcr-like) enzymes that activates the anaerobic degradation of non-methane alkanes has attracted much interest in the molecular mechanisms of C-H activation without oxygen. This review summarized the advances on function-structure-mechanism study of Mcr/Mcr-like enzymes. Additionally, future directions in anaerobic oxidation of alkanes and greenhouse-gas control using Mcr/Mcr-like enzymes were proposed.
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Archéobactéries/métabolisme , Méthane , Oxydoréduction , Oxidoreductases/métabolisme , PhylogenèseRésumé
Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.
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Humains , Antioxydants/pharmacologie , Apoptose/effets des médicaments et des substances chimiques , Inflammation/traitement médicamenteux , Ischémie/traitement médicamenteux , Méthane/usage thérapeutique , Lésion d'ischémie-reperfusion/traitement médicamenteuxRésumé
BACKGROUND/AIMS: This study aimed to identify the demographic and clinical factors associated with positive breath-test results and to assess the relationship between hydrogen and methane production in patients with suspected irritable bowel syndrome (IBS).METHODS: The demographic and clinical factors of 268 patients with suspected IBS, who had undergone a lactulose breath test, were analyzed.RESULTS: Of 268 patients included in this study, 143 (53.4%) were females. The median age and BMI of the patients was 58.0 years (range, 18.0–80.0 years) and 22.5 kg/m² (range, 14.4–34.3 kg/m²), respectively. A weak positive correlation was observed between the BMI and baseline hydrogen level (rho=0.134, p=0.031). Women were significantly more likely to show a ≥20 ppm increase in hydrogen within 90 min (early hydrogen increase, p=0.049), a ≥10 ppm increase in methane within 90 min (early methane increase, p=0.001), and a ≥10 ppm increase in methane between 90 min and 180 min (late methane increase, p=0.002) compared to men. The baseline hydrogen level was related to the baseline methane level (rho=0.592, p<0.001) and the maximal hydrogen level within 90 min was related to maximal methane level within 90 min (rho=0.721, p<0.001). Patients with an early hydrogen increase (43.8%) were more likely to show a positive result for an early methane increase compared to patients without an early increase in hydrogen (0%, p<0.001).CONCLUSIONS: Women were associated with high rates of positive lactulose breath-test results. In addition, methane production was correlated with hydrogen production.
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Femelle , Humains , Mâle , Tests d'analyse de l'haleine , Hydrogène , Syndrome du côlon irritable , Lactulose , Méthane , Caractères sexuelsRésumé
ABSTRACT Objective: To evaluate the association between small intestinal bacterial overgrowth (SIBO) and weight and height impairment in children and adolescents with gastroenterology diseases. Methods: Observational and retrospective study. All 162 patients aged less than 19 years old who underwent breath test in search of SIBO between 2011 and 2016 were studied. Breath test was collected after the intake of 10 grams of lactulose. The concentration of hydrogen and methane was measured for 180 minutes after the beginning of the test by 12i QuinTronMicroLyzer device. Results: SIBO was identified in 51 (31.5%) patients. There was no difference between the age of those with (mean=8.7y.o; 25th and 75th percentile: 4.6 and 11.3) and without (mean=7.9y.o 25th and 75th percentile: 4.8 and 12.2) SIBO (p=0.910). There was no association between gender and SIBO (male 26.3% vs. female 36.3%, p=1.00). A lower median of height-for-age Z score (mean=-1.32; 25th and 75th percentile: -2.12 and -0.08 vs. mean=-0.59; 25th and 75th percentile: -1.57 and 0.22; p=0.04) was demonstrated in children with SIBO when compared with children without it. There was no difference between the BMI-for-age Z score of patients with (mean=-0.48) and without SIBO (mean=-0.06) (p=0.106). The BMI of patients with SIBO (median=15.39) was lower than of those without it (median=16.06); however, the statistical analysis was not significant (p=0.052). The weight-for-age Z score was lower in patients with SIBO (mean=-0.96) than in those without SIBO (mean=-0.22) (p=0.02) Conclusions: Children and adolescents with SBIO associated with diseases of the gastrointestinal tract have lower weight and height values.
RESUMO Objetivo: Avaliar a existência de associação entre sobrecrescimento bacteriano no intestino delgado (SBID) e comprometimento de peso e estatura em crianças e adolescentes com doenças do aparelho digestivo. Métodos: Estudo observacional e retrospectivo em ambulatório de gastroenterologia pediátrica. Foram incluídos todos os 162 pacientes com idade inferior a 19 anos que realizaram teste respiratório para pesquisa de SBID entre 2011 e 2016. O teste respiratório foi realizado após ingestão de dez gramas de lactulose. Foram determinadas as concentrações de hidrogênio e metano em aparelho 12i QuinTron MicroLyzer até 180 minutos após o início do teste respiratório. Resultados: SBID foi caracterizado em 51 (31,5%) dos 162 pacientes. Não houve diferença na idade das crianças com (mediana=8,7 anos; percentil 25-75: 4,6-11,3) e sem (mediana=7,9 anos; percentil 25-75: 4,8-12,2) SBID (p=0,910). Não se observou associação entre SBID e sexo (masculino 27,4% e feminino 36,6%; p=0,283). O escore Z da estatura-idade nos pacientes com SBID (mediana=-1,32; percentil 25-75: -2,12—0,08) foi menor (p=0,040) do que naqueles sem SBID (mediana=-0,59; percentil 25-75: -1,57-0,22). Na comparação do escore Z de índice de massa corpórea-idade não foi observada diferença entre os grupos com (média=-0,489±1,528) e sem (média=-0,067±1,532) SBID (p=0,106). Nos pacientes com menos de 10 anos de idade, o escore Z de peso-idade foi menor nos pacientes com SBID (média=-0,968±1,359) do que nos sem SBID (média=-0,223±1,584) (p=0,026). Conclusões: Crianças e adolescentes com SBID associado a doenças do trato gastrintestinal apresentam menores valores de peso e estatura.
Sujets)
Humains , Mâle , Femelle , Enfant d'âge préscolaire , Enfant , Infections bactériennes/complications , Développement de l'enfant/physiologie , Maladies gastro-intestinales/microbiologie , Intestin grêle/microbiologie , Agents gastro-intestinaux/administration et posologie , Brésil/épidémiologie , Tests d'analyse de l'haleine/méthodes , Indice de masse corporelle , Études cas-témoins , Études rétrospectives , Hydrogène/analyse , Lactulose/administration et posologie , Méthane/analyseRésumé
En el sector de Quintero, desde los últimos 50 años han existido diversos hitos relacionados con la contaminación medioambiental. Iniciando con la instauración de la termoeléctrica "Ventanas" en 1950, Chilectra en 1958. En el año 1993 el ministerio de Agricultura de Chile declaró a Puchuncaví y Quintero como una "zona saturada de contaminación" por dióxido de azufre (SO2) y material particulado (MP10). En el año 2011, 135 trabajadores del complejo Ventana fallecieron producto del cáncer. Durante el 2014 hubo un derrame de petróleo en la Bahía de Quintero, 2015 un informe del Instituto de Fomento Pesquero (IFOP) arrojó cifras de arsénico que superan 23 veces la norma establecida por el Código Sanitario de Alimentos. Frente a dicho escenario, se hace evidente la necesidad de comprender cómo es la situación de los pobladores de dichas comunas. La presente investigación busca asociar los niveles de contaminación de las comuna de Quintero y el número de hospitalizaciones durante los años 2012 hasta el 2018.
In Quintero, since the last 50 years there have been various milestones related to environmental pollution. Starting with the installation of the "Ventanas" thermoelectric plant in 1950, Chilectra in 1958. In 1993, the Chilean Ministry of Agriculture declared Puchuncaví and Quintero as a "zone saturated with contamination" by sulfur dioxide (SO2) and particulate matter (MP10). In 2011, 135 workers at the Ventana complex died of cancer. During 2014 an oil spill emerged in Quintero Bay, 2015 a report by the Institute for Fisheries Development (IFOP) showed arsenic figures that exceed 23 times the norm established by the Sanitary Food Code. Faced with this scenario, the need to understand what the situation of the residents of said communes is like is evident. The present investigation seeks to associate the levels of contamination of the commun of Quintero and the number of hospitalizations during the years 2012 to 2018.
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Pollution de l'air , Exposition environnementale/statistiques et données numériques , Polluants environnementaux/analyse , Hospitalisation/statistiques et données numériques , Ozone/analyse , Dioxyde de soufre/analyse , Chili , Analyse de régression , Facteurs de risque , Réglementation gouvernementale , Méthane/analyse , Dioxyde d'azote/analyseRésumé
Background: Ammonium stress is a prime limiting phenomenon that occurs during methane formation from poultry manure. It is caused by elevated ammonium nitrogen concentrations that result from substrate decomposition. The amounts of methane formed depend on the activity of methanogenic microbes. Results: During the research reported in this paper, the response of a mesophilic consortium inhabiting a biogas reactor to rising load of poultry manure was investigated. The taxonomic composition of bacterial population was mostly typical, however syntrophic bacteria were not detected. This absence resulted in limitation of succession of some methanogenic microorganisms, especially obligate hydrogenotrophs. The methanogenic activity of the consortium was totally dependent on the activity of Methanosaeta. Inhibition of methanoganesis was noticed at ammonium nitrogen concentration of 3.68 g/L, total cessation occurred at 5.45 g/L. Significant amounts of acetic acid in the fermentation pulp accompanied the inhibition. Conclusions: The effectiveness of the consortium was totally dependent on the metabolic activity of the acetoclastic Methanoseata genus and lack of SAOB did not allow hydrogenotrophic methanogens to propagate and lead to cessation of biogas production at an elevated ammonium concentration at which acetoclastic methanogens were inhibited.
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Methanosarcinaceae/métabolisme , Biocarburants , Microbiote , Anaérobiose , Volaille , Stress physiologique , Réaction de polymérisation en chaîne , Profilage d'ADN , Chromatographie en phase liquide à haute performance , Archéobactéries/métabolisme , Biodiversité , Fermentation , Consortiums microbiens , Composés d'ammonium , Fumier , Méthane , AzoteRésumé
RESUMEN Objetivo. Evaluar el efecto de dosis crecientes del glucósido cianogénico Linamarina, en la reducción de metano ruminal in vitro. Materiales y Métodos. Se empleó líquido ruminal de dos ovejas fistuladas de la raza Merino Precoz, con el que se inoculó un sustrato fermentativo constituido por heno de alfalfa (Medicago sativa) y grano de avena molido (Avena sativa L.), se adicionó solución buffer y Linamarina (pureza de ≥98%) en dosis crecientes, lo que se llevó a incubación por ocho horas in vitro. El metano se midió cada hora, con un monitor de gases infrarrojo. Resultados. De acuerdo con el incremento de las dosis de Linamarina (0, 6, 13, 20 y 26 mg/L), la concentración de metano disminuyó de forma lineal (p≤0.05) en (9.7, 9.2, 18.1 y 29.4%) respectivamente. Se observó una reducción significativa de metano con la dosis más alta de Linamarina. Conclusión. La Linamarina, en su estado puro, fue eficaz en la reducción de metano durante la fermentación ruminal in vitro. Por lo tanto, este estudio constituye una base para futuros experimentos que incluyan fuentes vegetales de Linamarina y otras variables ruminales, lo que puede conducir a encontrar estrategias para reducir los gases de efecto invernadero.
ABSTRACT Objective. To assess the effect of rising doses of the cyanogenic glucoside Linamarin on the reduction of in vitro rumen methane. Materials and methods. Rumen fluid from two fistulated Merino Precoz sheep, inoculated with a fermentation substrate comprising alfalfa hay (Medicago sativa) and ground oat grain (Avena sativa L.), and added with buffer solution and Linamarin (purity ≥98%) in rising doses, was incubated for eight hours in vitro. Methane was measured each hour with an infrared gas monitor. Results. According Linamarin doses were increased (0, 6, 13, 20 and 26 mg/L), the methane concentration fell in a linear manner (p≤0.05) by (9.7, 9.2, 18.1 and 29.4%), respectively. A significant reduction of methane was seen whit the highest dose of Linamarin. Conclusions. Linamarin, in pure state, was effective to reduce methane during in vitro ruminal fermentation. Therefore, this study constitutes a basis for future experiments including vegetable sources of Linamarin as well as other rumen variables, leading to find a strategy for reducing greenhouse gases.
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Techniques in vitro , Additifs alimentaires , Glucosides , Méthane , FermentationRésumé
BACKGROUND: Triclosan (TCS) is an antimicrobial agent widely used in health care and consumer products. This compound is present in sludge of wastewater treatment plants (WWTPs), and because of its bactericidal characteristics, it can inhibit the methanogenic activity in anaerobic digestion (AD) technology. The aim of this study was to evaluate the toxic effects of TCS on the methanogenic activity. RESULTS: Batch anaerobic reactors were used with TCS concentrations of 7.8, 15.7, 23.5, and 31.4 mg/L. These assays consisted in three successive feedings (I, II, and III), wherein the sludge was exposed to each TCS concentration and volatile fatty acid (VFA) substrate. For evaluation of the residual sludge activity during feeding III, only VFA was used. The results showed that the increase in TCS concentrations correlated with the reduction in methane (CH4) production. In this case, the minimum values were achieved for TCS concentration of 31.4 mg/L with CH4 levels between 101.9 and 245.3 during feedings I, II, and III. Regarding the effect of TCS on VFA consumption, an inhibitory effect was detected for TCS concentrations of 23.5 and 31.4 mg/L, with concentrations of acetic, butyric, and propionic acids at the end of the assay (37 d) between 153.6 and 206.8, 62.5 and 60.1, and 93.4 and 110 mg/L, respectively. Regarding the removal of TCS during AD, these values were above 47%. Conclusion: TCS is an inhibitor of methanogenic activity with a decrease between 63 and 70% during the different feedings. The CH4 production was not recovered during feeding III, with inhibition percentages of 2172%.
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Triclosan/toxicité , Digestion Anaérobique , Méthane/métabolisme , Anti-infectieux/toxicité , Eaux d'égout , Station de Traitement des Eaux Usées , Chromatographie en phase liquide à haute performance , Acides gras volatils , AnaérobioseRésumé
BACKGROUND: The amount of municipal solid waste (MSW) gradually increased along with the rapid development of modern cities. A large amount of landfill leachate are generated with excessive chemical oxygen demand (COD), which create a great deal of pressure on the environment-friendly treatment process. Anaerobic digestion is an ideal technique to solve the above problem. RESULTS: A thermophilic granular sludge was successfully adapted for anaerobic digestion of MSW leachate (from an aging large-scale landfill) for methane production. The COD degradation efficiency improved by 81.8%, while the methane production rate reached 117.3 mL CH4/(g VS d), which was 2.34-fold more than the control condition. The bacterial and archaeal communities involved in the process were revealed by 16S rRNA gene high-throughput pyrosequencing. The richness of the bacterial community decreased in the process of thermophilic granular sludge, while the archaeal community structure presented a reverse phenomenon. The bacterial genus, Methanosaeta was the most abundant during the mesophilic process, while Methanobacterium, Methanoculleus, Methanosaeta and Methanosarcina were more evenly distributed. The more balanced community distribution between hydrogenotrophic and acetotrophic methanogens implied a closer interaction between the microbes, which further contributed to higher methane productivity. The detailed relationship between the key functional communities and anaerobic digestion performances were demonstrated via the multivariate canonical correspondence analysis. Conclusions: With the assistance of adaptive thermophilic granular sludge, microbial community structure was more evenly distributed, while both of COD degradation rate and methane production was improved during anaerobic digestion of MSW landfill leachate.
Sujets)
Bactéries anaérobies/métabolisme , Déchets solides , Digestion Anaérobique , Traitement des Boues , Méthane/métabolisme , Eaux d'égout/microbiologie , Bactéries anaérobies/isolement et purification , Polluants chimiques de l'eau , Réaction de polymérisation en chaîne , Zone Urbaine , Biocarburants , Analyse de la demande biologique en oxygène , Température élevée , AnaérobioseRésumé
Objectives: Small intestinal bacterial overgrowth (SIBO) is challenging to treat and diagnose and is associated with diagnosis of irritable bowel syndrome (IBS). Although no FDA-approved medications exist for treatment of SIBO, rifaximin has recently received approval to treat diarrhea-predominant IBS and patients with methane-positive SIBO breath tests. The aim of this study is to evaluate patient response to rifaximin for SIBO based on breath test results. Materials and methods: All patients underwent breath testing to evaluate for SIBO during a 42-month period. Patients were defined as having a positive glucose breath test for SIBO based on an increase of ≥ 20 ppm of hydrogen and/or ≥ 10 ppm of methane 90 minutes after ingesting glucose. Patient demographic and symptom data, antibiotic treatment regimens, symptomatic response to therapy, and repeat treatments were recorded. Institutional review board approval was obtained. Results: A total of 53 of 443 patients had positive breath testing for SIBO. Response rates to rifaximin (550 mg three times daily for 14 days) were 47.4% for hydrogen positivity alone and 80% for both hydrogen and methane positivity. Conclusions: Rifaximin was the most commonly prescribed antibiotic regimen for SIBO therapy. Patients with hydrogen or hydrogen and methane positive breath tests responded well to rifaximin therapy. For patients with hydrogen-positive SIBO, rifaximin may prove a highly effective therapy in providing symptom relief from the effects of SIBO.
Objetivos: El sobrecrecimiento bacteriano de intestino delgado es una entidad difícil de diagnosticar y tratar, frecuentemente asociada con el síndrome de intestino irritable. A pesar que la FDA no ha aprobado medicamentos para tratar el sobrecrecimiento bacteriano, la rifaximina ha sido recientemente aprobada para tratar el intestino irritable tipo diarrea y en pacientes con test de aliento metano positivo en sobrecrecimiento bacteriano. El objetivo del estudio fue evaluar la respuesta a rifaximina de los pacientes con sobrecremiento bacteriano con prueba de aliento positiva. Material y métodos: Todos los pacientes que se realizaron prueba de aliento por sobrecrecimiento bacteriano durante un periodo de 42 meses. Se definió un paciente con sobrecrecimiento bacteriano positivo si tenía un incremento mayor a 20 ppm de hidrógeno y/o 10 ppm de metano luego de 90 minutos de la ingesta de glucosa. Se registraron los datos demográficos, síntomas, tratamiento antibióticos recibidos, respuesta a la terapia, y repetición de tratamientos. Resultados: Un total de 53 de 443 pacientes tuvieron prueba de aliento positiva para sobrecrecimiento bacteriano. La tasa de respuesta a rifaximina (550 mg tres veces x día x 14 días) fue 47.4% para pacientes con sólo test de hidrógeno positivo, y 80% para pacientes con tanto test de hidrógeno como metano positivos. Conclusiones: La rifaximina es el régimen antibiótico más frecuentemente utilizado en sobrecrecimiento bacteriano. Los pacientes con prueba de aliento de hidrógeno o hidrógeno y metano positivos respondieron bien a la rifaximina. Para pacientes con sobrecrecimiento bacteriano prueba de hidrógeno positiva, la rifaximina puede ser una terapia efectiva en mejorar síntomas.
Sujets)
Adolescent , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Femelle , Humains , Mâle , Adulte d'âge moyen , Jeune adulte , Infections bactériennes/traitement médicamenteux , Rifaximine/usage thérapeutique , Intestin grêle/microbiologie , Antibactériens/usage thérapeutique , Infections bactériennes/diagnostic , Infections bactériennes/métabolisme , Tests d'analyse de l'haleine , Études rétrospectives , Résultat thérapeutique , Hydrogène/analyse , Hydrogène/métabolisme , Méthane/analyse , Méthane/métabolismeRésumé
BACKGROUND@#Asthma is a common cause of breathing difficulty in children and adults, and is characterized by chronic airway inflammation that is poorly controlled by available treatments. This results in severe disability and applies a huge burden to the public health system. Methane has been demonstrated to function as a therapeutic agent in many diseases. The aim of the present study was to explore the effect of methane-rich saline (MRS) on the pathophysiology of a mouse model of asthma and its underlying mechanism.@*METHODS@#A murine model of ovalbumin (OVA)-induced allergic asthma was applied in this study. Mice were divided into three groups: a control group, an OVA group, and OVA-induced asthmatic mice treated with MRS as the third group. Lung resistance index (RI) and dynamic compliance (Cdyn) were measured to determine airway hyper-responsiveness (AHR). Haematoxylin and eosin (H&E) staining was performed and scored to show histopathological changes. Cell counts of bronchoalveolar lavage fluid (BALF) were recorded. Cytokines interleukin (IL)-4, IL-5, IL-13, tumor necrosis factor α (TNF-α), and C-X-C motif chemokine ligand 15 (CXCL15) from BALF and serum were measured by enzyme-linked immunosorbent assay (ELISA). The oxidative stress indexes, including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), myeloperoxidase (MPO), and 8-hydroxydeoxyguanosine (8-OHdG), were determined using commercial kits. Apoptosis was evaluated by western blot, quantitative real-time polymerase chain reaction (qRT-PCR), and biochemical examination.@*RESULTS@#MRS administration reversed the OVA-induced AHR, attenuated the pathological inflammatory infiltration, and decreased the cytokines IL-4, IL-5, IL-13, TNF-α, and CXCL15 in serum and BALF. Moreover, following MRS administration, the oxidative stress was alleviated as indicated by decreased MDA, MPO, and 8-OHdG, and elevated SOD and GSH. In addition, MRS exhibited an anti-apoptotic effect in this model, protecting epithelial cells from damage.@*CONCLUSIONS@#Methane improves pulmonary function and decreases infiltrative inflammatory cells in the allergic asthmatic mouse model. This may be associated with its anti-inflammatory, antioxidative, and anti-apoptotic properties.
Sujets)
Animaux , Femelle , Souris , Apoptose/effets des médicaments et des substances chimiques , Asthme/métabolisme , Hyperréactivité bronchique/traitement médicamenteux , Cytokines/analyse , Inflammation/prévention et contrôle , Méthane/pharmacologie , Souris de lignée BALB C , Stress oxydatif/effets des médicaments et des substances chimiques , Solution physiologique saléeRésumé
BACKGROUND/AIMS: Recent studies suggest that air pollution may play a role in gastrointestinal disorders. However, the effect of long-term exposure to air pollution on childhood irritable bowel syndrome (IBS) is unclear. Hence, we conducted a nationwide cohort study to investigate the association between long-term air pollution exposure and the incidence and risk of IBS in Taiwanese children during 2000–2012. METHODS: We collected data from the Taiwan National Health Insurance Research Database, linked to the Taiwan Air Quality-Monitoring Database according to the insurant living area and the air quality-monitoring station locations. Children < 18 years old, identified from January 1st, 2000, were followed-up until IBS diagnosis or December 31st, 2012. The daily average air pollutant concentrations were categorized into 4 quartile-based groups (Q1–Q4). We measured the incidence rate, hazard ratios (HRs), and 95% confidence intervals for IBS stratified by the quartiles of air pollutant concentration. RESULTS: A total of 3537 children (1.39%) were diagnosed with IBS within the cohort during the follow-up period. The incidence rate for IBS increased from 0.84 to 1.76, from 0.73 to 1.68, from 0.85 to 1.98, and from 0.52 to 3.22 per 1000 person-years, with increase in the carbon monoxide, nitrogen dioxide, non-methane hydrocarbon, and methane quartile (from Q1 to Q4) exposure concentration, respectively. The adjusted HR for IBS increased with elevated carbon monoxide, nitrogen dioxide, non-methane hydrocarbon, and methane exposure in Q4 to 1.98, 2.14, 2.19, and 5.87, respectively, compared with Q1. CONCLUSION: Long-term ambient air pollutant exposure is an environmental risk factor for childhood IBS.