RESUMO
Background: Polymyxin B is considered a last-line therapeutic option against multidrug-resistant gram-negative bacteria, especially in COVID-19 coinfections or other serious infections. However, the risk of antimicrobial resistance and its spread to the environment should be brought to the forefront. Methods: Pandoraea pnomenusa M202 was isolated under selection with 8 mg/L polymyxin B from hospital sewage and then was sequenced by the PacBio RS II and Illumina HiSeq 4000 platforms. Mating experiments were performed to evaluate the transfer of the major facilitator superfamily (MFS) transporter in genomic islands (GIs) to Escherichia coli 25DN. The recombinant E. coli strain Mrc-3 harboring MFS transporter encoding gene FKQ53_RS21695 was also constructed. The influence of efflux pump inhibitors (EPIs) on MICs was determined. The mechanism of polymyxin B excretion mediated by FKQ53_RS21695 was investigated by Discovery Studio 2.0 based on homology modeling. Results: The MIC of polymyxin B for the multidrug-resistant bacterial strain P. pnomenusa M202, isolated from hospital sewage, was 96 mg/L. GI-M202a, harboring an MFS transporter-encoding gene and conjugative transfer protein-encoding genes of the type IV secretion system, was identified in P. pnomenusa M202. The mating experiment between M202 and E. coli 25DN reflected the transferability of polymyxin B resistance via GI-M202a. EPI and heterogeneous expression assays also suggested that the MFS transporter gene FKQ53_RS21695 in GI-M202a was responsible for polymyxin B resistance. Molecular docking revealed that the polymyxin B fatty acyl group inserts into the hydrophobic region of the transmembrane core with Pi-alkyl and unfavorable bump interactions, and then polymyxin B rotates around Tyr43 to externally display the peptide group during the efflux process, accompanied by an inward-to-outward conformational change in the MFS transporter...(AU)
Assuntos
Humanos , Polimixina B , Simulação de Acoplamento Molecular , Proteínas de Membrana Transportadoras , Ilhas Genômicas , Antibacterianos , Escherichia coli/genética , Microbiologia , Técnicas Microbiológicas , Águas Residuárias , Testes de Sensibilidade MicrobianaRESUMO
Photosynthetic microbial fuel cell (PMFC) is a novel technology, which employs organic pollutants and organisms to produce electrons and biomass and capture CO2 by bio-reactions. In this study, a new PMFC was developed based on Synechococcus sp. as a biocathode, and dairy wastewater was used in the anode chamber. Different experiments including batch feed mode, semi-continuous feed mode, Synechococcus feedstock to the anode chamber, Synechococcus-Chlorella mixed system, the feedstock of treated wastewater to the cathode chamber, and use of extra nutrients in the anodic chamber were performed to investigate the behavior of the PMFC system. The results indicated that the PMFC with a semi-continuous feed mode is more effective than a batch mode for electricity generation and pollutant removal. Herein, maximum power density, chemical oxygen demand removal, and Coulombic efficiency were 6.95 mW/m2 (450 Ω internal resistance), 62.94, and 43.16%, respectively, through mixing Synechococcus sp. and Chlorella algae in the batch-fed mode. The maximum nitrate and orthophosphate removal rates were 98.83 and 68.5%, respectively, wherein treated wastewater in the anode was added to the cathode. No significant difference in Synechococcus growth rate was found between the cathodic chamber of PMFC and the control cultivation cell. The heating value of the biocathode biomass at maximum Synechococcus growth rate (adding glucose into the anode chamber) was 0.2235 MJ/Kg, indicating the cells high ability for carbon dioxide recovery. This study investigated not only simultaneous bioelectricity production and dairy wastewater in a new PMFC using Synechococcus sp. but also studied several operational parameters and presented useful information about their effect on PMFC performance.(AU)
Assuntos
Fontes de Energia Bioelétrica/microbiologia , Synechococcus , Eletricidade , Chlorella/microbiologia , Poder Calorífico , Biomassa , Microbiologia , Águas Residuárias/microbiologiaRESUMO
Tangxun Lake is the largest urban lake in China, which is polluted by multiple wastewaters, and now is severely eutrophic. We detected diversity, abundance, and the coexistence of Candidatus Methylomirabilis oxyfera-like and anammox bacteria in different horizontal and vertical directions of the lake sediments through qPCR and clone library. Phylogenetic tree analysis showed that the Ca. Methylomirabilis oxyfera-like and anammox bacteria exhibited high diversity, and they belonged to group BE and Ca. Brocadia genus, respectively. These two bacteria displayed higher diversity in polluted area than in other areas. Furthermore, they had great spatial variation of abundance both horizontally and vertically. The abundance of anammox bacteria was significantly higher than that of Ca. Methylomirabilis oxyfera-like bacteria. The stronger the human interference were, the higher abundances these two bacteria exhibited horizontally, whereas both their abundances and the ratio of anammox to Ca. Methylomirabilis oxyfera-like bacteria decreased with the increasing depth. Redundancy analysis indicated that nitrate was the most influential environmental factor to the abundance of these two bacteria. Ammonia, nitrite, total nitrogen, and organic matters were in positive correlation with the abundance of these two bacteria. Nitrate was slightly negatively correlated with the abundance of Ca. Methylomirabilis oxyfera-like bacteria, while it was positively correlated with that of anammox bacteria. Our results provided an insight into the effects of environmental factors such as ammonia, nitrite, and nitrate on the diversity and abundances of these two bacteria and theoretical basis for restoration of water.(AU)
Assuntos
Humanos , Águas Residuárias/microbiologia , Microbiologia da Água , Bactérias , Nitratos , Sedimentos , Microbiologia , ChinaRESUMO
Ibuprofen (IBU) is the third most commonly used analgesic drug in the world. It enters the water system as a result of human excretion-based wastewater discharges. Hence, it attracts the attention of environmentalists for its ecological fate and degradation behavior. In this study, the two IBU degrading bacterial strains, Citrobacter freundii strain PYI-2 (MT039504) and Citrobacter portucalensis strain YPI-2 (MN744335), were isolated from industrial wastewater samples using an enrichment culture method, identified, and characterized. Physiological and batch culture degradation studies have indicated that these strains involved in IBU degradation and the intermediates produced during the process were analyzed. These strains degrade IBU in the batch culture. The optimum pH was reported for degradation of the PYI2 strain (6.9) and YPI2 strain (5.8), and the optimum temperatures were 42°C and 32°C, respectively. Biomass kinetic analysis of these strains was performed based on physical parameters (temperature, pH, and rpm) and confirmed by the experimental study. As indicated in the GC-MS chromatogram peaks, viz., hydroxyibuprofen, 2-(4-hydroxyphenylpropionic acid), 1,4-hydroquinone, and 2-hydroxy-1,4-quinol various intermediates compounds of degradation pathway were observed. Finally, through the GC-MS data, the metabolic pathway for degradation was predicted. In the study, it was confirmed that Citrobacter freundii strain PYI-2 and Citrobacter portucalensis strain YPI-2 exhibit metabolic potential for the biodegradation of IBU and can be further deployed in bioremediation.(AU)
Assuntos
Humanos , Ibuprofeno , Águas Residuárias , Cromatografia Gasosa-Espectrometria de Massas , Citrobacter freundii , MicrobiologiaRESUMO
Scarcity of water and energy, and legal requirements for discharge of waste and wastewater are forcing hemodialysis facilities to change their approach to a more integrated concept of connecting the residual output (in terms of waste, wastewater and energy loss) to the input (in terms of water and energy). Zero liquid discharge is an expanding water treatment philosophy in which hemodialysis wastewater is purified and recycled, leaving little to no effluent remaining when the process is complete, thereby saving money and being beneficial to the environment. This article explores the possible ways to treat hemodialysis wastewater, thus achieving ZLD conditions. (AU)
La escasez de agua y energía, y los requisitos legales para la descarga de desechos y aguas residuales están obligando a las instalaciones de hemodiálisis a cambiar su enfoque hacia un concepto más integrado de conectar la salida residual (en términos de desechos, aguas residuales y pérdida de energía) con la entrada (en términos de agua y energía). La descarga de líquido cero es una filosofía de tratamiento de agua en expansión en la que las aguas residuales de hemodiálisis se purifican y se reciclan, dejando poco o ningún efluente cuando se completa el proceso, lo que ahorra dinero y es beneficioso para el medio ambiente. Este artículo explora las posibles formas de tratar las aguas residuales de hemodiálisis, logrando así las condiciones de descarga de líquidos cero. (AU)
Assuntos
Humanos , Diálise Renal , Purificação da Água , Águas Residuárias , Conservação dos Recursos Hídricos , Soluções para DiáliseRESUMO
El análisis de aguas residuales con fines epidemiológicos es actualmente una herramienta fiable y complementaria a las metodologías basadas en indicadores tradicionales para el control de diferentes sustancias entre las que cabe destacar las drogas. Si bien varios países europeos la utilizan como herramienta de trabajo para la monitorización de drogas de abuso, en España su uso se limita principalmente a estudios realizados por diferentes grupos de investigación, tal y como se describe en el caso práctico puesto de ejemplo en el artículo. Sin embargo, el potencial de la metodología ha quedado evidenciado en los estudios científicos llevados a cabo tanto a nivel español como internacional y, aunque son necesarios más estudios para llegar a conocer todo su potencial, se prevé pueda ser incorporada como herramienta de trabajo complementaria a las que habitualmente se utilizan. En este sentido, la Red Española de Análisis de Aguas Residuales (ESAR-Net), creada en 2017 y formada por diferentes grupos de investigación españoles, pretende contribuir al conocimiento y aplicación de esta metodología en España a través de actividades científicas y de divulgación
Wastewater-Based Epidemiology is currently a reliable and complementary tool to methodologies based on traditional indicators for the control of various substances such as drugs. Although several European countries use it as a working tool for the monitoring of drugs of abuse, in Spain its use is mainly limited to studies carried out by different research groups, as described in the case study used as an example in the article. However, the potential of the methodology has been demonstrated in the scientific studies carried out both at the Spanish and international level and, although more studies are necessary to get to know its full potential, it is expected that it could be incorporated as a complementary work tool to those that are usually used. In this sense, the Red Española de Análisis de Aguas Residuales (ESAR-Net), created in 2017 and formed by different Spanish research groups, aims to contribute to the knowledge and application of this methodology in Spain through scientific and outreach activities
Assuntos
Humanos , Monitoramento Ambiental , Águas Residuárias/química , Drogas Ilícitas/análise , Detecção do Abuso de Substâncias/métodos , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Águas Residuárias/análise , Drogas Ilícitas/classificação , EspanhaRESUMO
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Assuntos
Humanos , Masculino , Pessoa de Meia-Idade , Águas Residuárias , Esporos Fúngicos/isolamento & purificação , Micélio/isolamento & purificação , Dermatomicoses/etiologia , Dermatomicoses/diagnósticoRESUMO
Las estaciones depuradoras de aguas residuales reciben una gran cantidad de compuestos disruptores endocrinos procedentes de domicilios, hospitales e industrias. Estas sustancias terminan por ser eliminadas, tratadas o no, al medio ambiente acuático próximo, detectándose a concentraciones muy bajas (ng/L o mig/L) en los efluentes de las plantas de tratamiento, en las aguas superficiales y en los sedimentos. A pesar de las bajas concentraciones, estas sustancias son biológicamente activas y pueden originar efectos adversos, entre otros procesos de estrés oxidativo y daño celular en las proteínas, ADN, carbohidratos y especialmente en los lípidos (peroxidación lipídica), en los organismos acuáticos. Tales procesos son consecuencia de la formación de especies reactivas generadas a partir de dichos compuestos. En este trabajo, se recopilan las concentraciones de los compuestos disruptores endocrinos que potencialmente originan situaciones de estrés oxidativo en organismos acuáticos, detectadas, así como los efectos de estos compuestos en biomarcadores de estrés oxidativo (niveles de glutatión reducido, actividades superóxido dismutasa, catalasa, glutatión peroxidasa) y daño celular (niveles de malondialdehído y de sustancias que reaccionan con el ácido tiobarbitúrico) de tales organismos
A large amount of endocrine disrupting compounds from homes, hospitals and industries are transported to wastewater treatment plants. These substances end up being discharged, treated or not, into the nearby aquatic environment, being found at very low concentrations ranging between nanograms and micrograms per liter in the effluents of the treatment plants, in the surface waters and in the sediments. These concentrations are sufficient to cause oxidative stress processes and cellular damage in proteins, ADN, carbohydrates, and especially in lipids (lipid peroxidation) in aquatic organisms. Such processes are a consequence of the formation of reactive species generated from these compounds. In this work, concentrations of endocrine disrupting compounds capable of causing oxidative stress in organisms from aquatic compartment are collected, as well as the effects of these in oxidative stress biomarkers (levels of reduced glutathione, activities superoxide dismutase, catalase, glutathione peroxidase) and cellular damage biomarkers (levels of malondialdehyde and substances that react with thiobarbituric acid) in such as organisms
Assuntos
Animais , Disruptores Endócrinos/farmacologia , Biomarcadores Ambientais , Estresse Oxidativo/efeitos dos fármacos , Águas Residuárias/química , PeixesRESUMO
Effluents from petroleum refineries contain a toxic mixture of sulfide, nitrogen, and phenolic compounds that require adequate treatment for their removal. Biological denitrification processes are a cost-effective option for the treatment of these effluents, but the knowledge on the microbial interactions in simultaneous sulfide and phenol oxidation in denitrifying reactors is still very limited. In this work, microbial community structure and macrostructure of granular biomass were studied in three denitrifying reactors treating a mixture of inorganic (sulfide) and organic (p-cresol) electron donors for their simultaneous removal. The differences in the available substrates resulted in different community assemblies that supported high removal efficiencies, indicating the community adaptation capacity to the fluctuating compositions of industrial effluents. The three reactors were dominated by nitrate reducing and denitrifying bacteria where Thiobacillus spp. were the prevalent denitrifying organisms. The toxicity and lack of adequate substrates caused the endogenous decay of the biomass, leading to release of organic matter that maintained a diverse although not very abundant group of heterotrophs. The endogenous digestion of the granules caused the degradation of its macrostructure, which should be considered to further develop the denitrification process in sulfur-based granular reactors for treatment of industrial wastewater with toxic compounds
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Assuntos
Águas Residuárias/microbiologia , Desnitrificação , Microbiota , Sulfetos/metabolismo , Cresóis/química , Bactérias/metabolismo , Indústria de Petróleo e Gás , Ciclo do Nitrogênio , Sulfetos/química , Nitratos/química , Thiobacillus/isolamento & purificação , BiomassaRESUMO
En el presente estudio, se realiza una revisión bibliográfica de los datos publicados de concentraciones de cafeína y su principal metabolito, la paraxantina, en el agua como matriz ambiental. Se recopilan las concentraciones de muestras procedentes de aguas influentes y efluentes de estaciones depuradoras de agua residual (EDAR), de aguas superficiales y de aguas potables de España. Los valores máximos de cafeína estarían ubicados en la provincia de Madrid con una concentración de 13.167 ngL-1 en agua superficial. Le sigue la provincia de Sevilla con 3.840 ngL-1 en agua de influente. La máxima concentración de cafeína en agua potable también se situaría en Madrid con 75 ngL-1. Con el método de cocientes de riesgo (Hazard quotients, HQs), los resultados indican que Madrid podría presentar posibles efectos adversos con un valor de HQ=0,25. El riesgo de aparición de cafeína en los ecosistemas acuáticos estaría relacionado con la densidad de población y la proximidad de núcleos poblacionales al medio fluvial, y su aparición en el agua superficial y potable estaría estrechamente ligada a la ineficiencia de los sistemas de depuración de aguas residuales y estaciones de tratamiento de aguas potables. Se necesitan estudios de toxicidad crónica para evaluar el riesgo real que podría tener la cafeína de forma aislada y combinada con otros contaminantes emergentes sobre los organismos expuestos (AU)
Literature review of caffeine in surface waters and Hazard quotients analysis in Spain. More and more research is being conducted on emerging contaminants. This study undertakes a literature review of data from concentrations of caffeine and its metabolite paraxanthine in wáter as a biological matrix. The concentrations of samples from influent and effluents wastewater treatment plants (WWTP), surface wáter and drinking water from Spain are collected. The maximum values of caffeine found in the literature are located in Madrid province with a concentration equal to 13,167 ngL-1 in surface water and 5,690 ngL-1. It follows Seville province with 3,840 ngL-1 in influent WWTP. The highest concentration of caffeine in drinking water also is located in Madrid with 75 ngL-1. Risk characterization with Hazard quotients (HQ) of caffeine as an environmental pollutant on our aquatic ecosystems is made. Madrid is the riskiest region with a HQ= 0.25 value. Risk occurrence of caffeine in aquatic ecosystems is related to opulation density and the proximity of towns to the fluvial environment. The appearance of caffeine in surface water and drinking water would be closely linked to the inefficiency of wastewater treatment systems and drinking water treatment plants. Inefficient sewage-treatment systems are shown to be closely linked with the emergence of caffeine in drinking and surface water. Chronic toxicity studies are needed to reveal the real risk that single and combined caffeine could have with other emerging pollutants on exposed organisms because, even though the amounts of caffeine are microgL-1 to ngL-1, the effect on organisms is not known when they are exposed to these amounts on a continuous basis into the environmental compartments (AU)
Assuntos
Cafeína/toxicidade , Poluição da Água/análise , Poluentes da Água/isolamento & purificação , Águas Superficiais , Água Potável/análise , Águas Residuárias/análise , Fauna Aquática/análiseRESUMO
Acinetobacter baumannii origin and itsepidemiology is under a great concern worldwide since this microorganism has become a leading nosocomial pathogen of the 21 th century among the "ESKAPE" group of microorganisms. The aim of the study was to monitor and explore the epidemiology of this important hospital pathogen in the second largest clinical university hospital in Croatia. The presence of A. baumannii in hospital wastewater, as a route for possible transmission outside of the hospital setting, as well as its survival in environmental conditions including seawater, was investigated. During the examination period ten both carbapenem and multidrug-resistant isolates of A. baumannii were recovered from hospital wastewater and compared to the clinical isolates originating from the same monitoring period. Multiplex PCR confirmed that four wastewater isolates harboured bla OXA-23-like ,while five wastewater isolatesharboured bla OXA-40-like genes sharing 100% sequence identity with bla OXA-72 sequence described in the same hospital in 2009, confirming the presence of an endemic cluster. Survival of A. baumannii in natural seawater was examined during 50 days of monitoring and to the best of our knowledge, was performed for the first time
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Assuntos
Acinetobacter baumannii/isolamento & purificação , Infecções por Acinetobacter/transmissão , Águas Residuárias/microbiologia , Carbapenêmicos/farmacocinética , Farmacorresistência Bacteriana , Resíduos de Serviços de Saúde/análise , Infecção Hospitalar/microbiologiaRESUMO
Las aguas residuales urbanas depuradas/regeneradas se han convertido en un recurso hídrico alternativo importante, como parte del uso y la gestión sostenible del agua, especialmente en zonas áridas con déficit en recursos naturales. Una de las aplicaciones de mayor interés es el riego agrícola, sector económico que demanda grandes cantidades de agua. Las etapas clásicas de tratamiento primario y secundario biológico suministran efluentes con aplicaciones limitadas para riego, pero se pueden mejorar sensiblemente si tales efluentes se someten a un proceso de ultrafiltración con membranas. En este trabajo se analizan los resultados de un estudio que correlaciona los parámetros físicoquímicos de calidad con sus propiedades fitotóxicas, en efluentes primarios y secundarios, y el efecto que produce la ultrafiltración con membranas en tales efluentes. En cada muestra se determinó: conductividad, turbidez, carbono orgánico total, proteínas solubles, polisacáridos, demanda química de oxígeno y los iones de Na+, K+, Ca2+, Mg2+, B3+, F-, Cl-. Los criterios de fitotoxicidad se evaluaron mediante el biomarcador Lactuca sativa L. Se concluye que la conductividad y la fitotoxicidad son parámetros interdependientes al evaluar el efecto tóxico durante los procesos de tratamiento de las aguas residuales. Por otra parte, el ion Cl- puede jugar un rol fitotóxico en los permeados que se obtienen cuando se someten a ultrafiltración los efluentes primarios y secundarios (AU)
The clean / reclaimed waste water has become an important alternative water resources as part of sustainable use and management of water, especially in arid areas with deficits in natural resources. One application of interest is the agricultural irrigation industry that requires large amounts of water. The classic stages of primary and secondary biological treatment supply effluents with limited applications for irrigation, but can be improved significantly if such effluents undergo a process of ultrafiltration membranes. This paper presents the results of a study correlating the physical and chemical quality with phytotoxic properties, parameters in primary and secondary effluents and the effect of the ultrafiltration membrane in such effluents are analyzed. In each sample was measured: conductivity, turbidity, total organic carbon, soluble proteins, polysaccharides, chemical oxygen demand and ions of Na+, K+, Ca2+, Mg2+, B3+, F- and Cl-. Criteria phytotoxicity were evaluated by Lactuca sativa L. Biomarker is concluded that phytotoxicity conductivity and are interdependent to evaluate the toxic effect treatment processes for wastewater parameters. Moreover, the Na+ and Cl- ions may play a role in the permeates phytotoxic obtained when subjected to ultrafiltration primary and secondary effluents (AU)
Assuntos
Ultrafiltração/instrumentação , Ultrafiltração/métodos , Ultrafiltração , Purificação da Água/instrumentação , Purificação da Água/métodos , Purificação da Água/normas , 51793/métodos , Efluentes Primários/métodos , Efluentes Primários/prevenção & controle , Efluentes Primários/estatística & dados numéricos , Esgotos Domésticos , Águas Residuárias/toxicidade , Compostos de Alumínio/toxicidade , Efluentes Primários/efeitos adversos , Efluentes Primários/análiseRESUMO
Objectives: Enterococci are intrinsically resistant to many commonly used antimicrobial agents. They are able to acquire resistance with relative ease and can spread these genes to other species. Enterococci resistant to antibiotics are associated with the use of these in clinical practice and also the spread of resistant clones in the world. The aim of this work was to compare the characteristics of the strains of vancomycin-resistant enterococci (VRE) isolated from municipal wastewater and hospital effluent. Methods: Samples were obtained from the effluent of the Hospital Universitario José de San Martín (Buenos Aires) and the municipal wastewater of the city of Buenos Aires. Results: The bacterial counts of VRE were greater in the hospital effluent, with an odds ratio of 36.4 (95% CI: 26.0-50.8; p<0.0001). The VRE isolated were mainly identified as E. faecium. The results indicate a high prevalence of enterococci resistant to the antibiotics tested. Conclusion: We may conclude that the effluents of hospitals constitute a source of VRE showing multiple resistance to antibiotics
Objetivos: Las especies de enterococos son intrínsecamente resistentes a varios antibióticos, adquieren resistencia con relativa facilidad, y difunden estos genes de resistencia a otras especies. La resistencia a los antibióticos en enterococos está asociada al uso de los mismos en la clínica médica y también a la diseminación de clones resistentes en el mundo. El objetivo de este trabajo fue comparar las características de las cepas de enterococos resistentes a vancomicina (ERV) aisladas en efluentes hospitalarios y aguas residuales urbanas. Métodos: Se obtuvieron muestras de los efluentes del Hospital Universitario José de San Martín (Buenos Aires) y muestras de aguas residuales urbanas de la ciudad de Buenos Aires. Resultados: Los recuentos de ERV fueron mayores en los efluentes hospitalarios, siendo la odds ratio 36.4 (IC95%: 26.0-50.8; p<0.0001). Los ERV aislados se identificaron principalmente como E. faecium. Los resultados indicaron una alta prevalencia de enterococos resistentes al resto de los antibióticos ensayados. Conclusión: Podemos concluir que los efluentes de los centros hospitalarios constituyen una fuente de enterococos de resistencia múltiple a antibióticos
Assuntos
Enterococos Resistentes à Vancomicina , Enterococos Resistentes à Vancomicina/isolamento & purificação , Águas Residuárias/análise , Águas Residuárias/microbiologia , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Enterococcus faecium/isolamento & purificação , Resistência a Vancomicina , Enterococcus faecium , Controle de Infecções/métodosRESUMO
To improve bacterial hydrogen production, ten hydrogen-producing strains belonging to Clostridium spp. were isolated from various sludges under low vacuum. Hydrogenogenesis by dark fermentation in batch cultures of these strains was optimal at about 35 ºC and an initial pH of 6.5, which for all strains gradually dropped to ca. pH 4 during the fermentation. Clostridium roseum H5 and C. diolis RT2 had the highest hydrogen yields per total substrate (120 ml H2/g initial COD). Substrate consumption alone by C. beijerinckii UAM and C. diolis RT2 reached 573 and 475 ml H2/g consumed COD, respectively. Butyric acid fermentation was predominant, with butyrate and acetate as the major by-products and propionate, ethanol, and lactate as secondary metabolites. The acetate: butyrate ratios and fermentation pathways varied depending on the strains and environmental conditions. Hydrogenogenesis was studied in greater detail in C. saccharobutylicum H1. In butyric acid fermentation by this representative strain, acetoacetate was detected as an intermediate metabolite. Hydrogenogenesis was also analyzed in an enrichment culture, which behaved similarly to the axenic cultures (AU)
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Assuntos
Águas Residuárias/microbiologia , Hidrogênio/isolamento & purificação , Clostridium/crescimento & desenvolvimento , Fermentação , Biodegradação Ambiental , Acetoacetatos/análise , Cultura AxênicaRESUMO
Haloferax mediterranei is a denitrifying halophilic archaeon able to reduce nitrate and nitrite under oxic and anoxic conditions. In the presence of oxygen, nitrate and nitrite are used as nitrogen sources for growth. Under oxygen scarcity, this haloarchaeon uses both ions as electron acceptors via a denitrification pathway. In the present work, the maximal nitrite concentration tolerated by this organism was determined by studying the growth of H. mediterranei in minimal medium containing 30, 40 and 50 mM nitrite as sole nitrogen source and under initial oxic conditions at 42 °C. The results showed the ability of H. mediterranei to withstand nitrite concentrations up to 50 mM. At the beginning of the incubation, nitrate was detected in the medium, probably due to the spontaneous oxidation of nitrite under the initial oxic conditions. The complete removal of nitrite and nitrate was accomplished in most of the tested conditions, except in culture medium containing 50 mM nitrite, suggesting that this concentration compromised the denitrification capacity of the cells. Nitrite and nitrate reductases activities were analyzed at different growth stages of H. mediterranei. In all cases, the activities of the respiratory enzymes were higher than their assimilative counterparts; this was especially the case for NirK. The denitrifying and possibly detoxifying role of this enzyme might explain the high nitrite tolerance of H. mediterranei. This archaeon was also able to remove 60 % of the nitrate and 75 % of the nitrite initially present in brine samples collected from a wastewater treatment facility. These results suggest that H. mediterranei, and probably other halophilic denitrifying Archaea, are suitable candidates for the bioremediation of brines with high nitrite and nitrate concentrations (AU)
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Assuntos
Haloferax mediterranei/enzimologia , Haloferax mediterranei/crescimento & desenvolvimento , Haloferax mediterranei/metabolismo , Nitratos/metabolismo , Nitrito Redutases/metabolismo , Nitritos/metabolismo , Comércio/metabolismo , Eliminação de Resíduos Líquidos/métodos , Desnitrificação , Recuperação e Remediação Ambiental/métodos , Oxirredução , Águas Residuárias/microbiologiaRESUMO
This study evaluates the utilization of lactose (Lac) and the presence of the phospho-β-galactosidase (lacG) gene as markers for distinguishing between fish (Lac-/lacG-) and dairy isolates (Lac+/lacG+) of Lactococcus garvieae, using a panel of L. garvieae isolates from different sources. None of the fish isolates produced acid from lactose (Lac-), however Lac-/lacG- isolates were observed in pigs, cows, birds and humans. Most of the dairy isolates (77.8%) were Lac+/lacG+, but some dairy isolates did not produce acid from this sugar. Data in the present study show that the ability to metabolize lactose and the presence of the lacG gene are heterogeneously scattered among L. garvieae isolates of different sources. Therefore, the use of these criteria as markers to differentiate between L. garvieae isolates of dairy and fish origin should be considered with caution (AU)
No disponible
Assuntos
Humanos , Animais , Bovinos , Laticínios/microbiologia , Peixes/microbiologia , Lactococcus/genética , Lactococcus/isolamento & purificação , Lactose/metabolismo , beta-Galactosidase/genética , Bacteriemia/microbiologia , Bacteriúria/microbiologia , Água Doce/microbiologia , Águas Residuárias/microbiologia , Pele/microbiologiaRESUMO
Microbial populations associated with methanogenic fixed- or floating-bed bioreactors used for anaerobic digestion of lignocellulosic waste were investigated. Fluorescent in situ hybridization (FISH) was used to characterize microorganisms in samples obtained from different heights in the reactors, which were operated in a semi-continuous manner (feeding and mixing once every 2 days). The FISH results showed that Methanosaeta concilii cells were most numerous at the bottom of both reactors. M. concilii cells were more abundant in the fixed-bed reactor (FXBR), which performed better than the floating-bed reactor (FLBR). Species of the Methanosarcina genera (mainly M. barkeri and M. mazei) were also observed in the FLBR but rarely in the FXBR. Methane production in each of the reactors ranged from 0.29 to 0.33 m3 CH(4)/kg COD(rem) (chemical oxygen demand removed). The removal of volatile fatty acids (VFA; 70-75 h) in the FXBR was more efficient than in the FLBR (AU)
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Assuntos
Águas Residuárias/microbiologia , Digestão de Lodos , Methanosarcinales/patogenicidade , Methanosarcina/patogenicidade , Biodegradação Ambiental , Sondas de Oligonucleotídeos/análise , Biocombustíveis , Microbiologia da ÁguaRESUMO
Protists, mainly ciliates, play several essential roles in biological wastewater treatment, such as the transfer of matter and energy, bacterial predation, and the removal of organic material. Moreover, during the treatment process, the formation of bioaggregates-flocs and biofilms-is essential to obtaining high-quality effluents. In the present study, Tetrahymena thermophila was used as a model organism to demonstrate the contribution of ciliates to bioflocculation. Axenic cultures of this species were exposed to chemical and mechanical stimuli that promote bioaggregation. In either case, the secretion of a capsulate mucous material by the ciliates or by particle aggregation was detected. Numerous, small, loosely compacted flocs were observed under shaking conditions and in the presence of latex beads. The composition of the exopolymeric material secreted by ciliates was analyzed by a series of fluorochromes and colorimetric methods, which showed that carbohydrates and nucleic acids were the main components involved in matrix formation and particle adhesion (AU)
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