Identification of active denitrifiers by DNA-Stable Isotope Probing and amplicon sequencing reveals Betaproteobacteria as responsible for attenuation of nitrate contamination in a low impacted aquifer

Groundwater reservoirs constitute important freshwater resources. However, these ecosystems are highly vulnerable to contamination and have to rely on the resident microbiota to attenuate the impact of this contamination. Nitrate is one of the main contaminants found in groundwater and denitrification is the main process that removes the compound. In this study, the response to nutrient load on indigenous microbial communities in groundwater from a low impacted aquifer in Uruguay was evaluated. Denitrification rates were measured in groundwater samples from three different sites with nitrate, acetate and pyrite amendments. Results showed that denitrification is feasible under in situ nitrate and electron donor concentrations, although the lack of readily available organic energy source would limit the attenuation of higher nitrate concentrations. DNA Stable-isotope probing (SIP), combined with amplicon sequencing of 16S rRNA, nirS and nirK genes, was used to identify the active denitrifiers. Members of the phylum Betaproteobacteria were the dominant denitrifiers in two of three sites, with different families being observed; members of the genus Vogesella (Neisseriaceae) were key denitrifiers at one site, while the genera Dechloromonas (Rhodocyclaceae) or Comamonas (Comamonadaceae) were the main denitrifiers detected at the other sites

Determination of atrazine and intermediates of biodegradation in a liquid culture medium for the enrichment of the microbial consorcia

1-chloro-3-ethylamino-5-isopropylamino-2 ,4,6-triazine, is an herbicide used to control annual weeds and perennial grasses. Although this herbicide is banned in the European Union for its toxicity, it is still widely used. Also, its the second most frecuently employed in Uruguay. The main mechanism for removal of atrazine in neutral pH environments is the bacterial degradation. The microorganisms can mineralize atrazine giving ammonia and carbon dioxide or they can degrade it to intermediates which vary in persistence and toxicity. The separation and detection of atrazine intermediates is important to know the health risk that represents its partial degradation in the environment. Furthermore, the separation method could be usefull to characterize bacterial degraders with potential application in biorremediation. Among the atrazine biodegradation intermediates are the hidroxyatrazine, the desetylhidroxyatrazine, the desisopropylhidrtoxyatrazine and cyanuric acid. In this paper we developed a method to separate atrazine and metabolites in a synthetic culture medium used to select atrazine degrading bacteria. For this technique we optimized a high performance liquid chromatography (HPLC) ion pair method using an C8 column, mobile phase acetonitrile / water, gradient flow and an UV detector. We evaluated its application to detect intermediates in several bacterial enrichments. It was found that the method is suitable to distinguish different metabolic capabilities of these enrichment.La atrazina, 1-cloro-3-etilamino-5-isopropilamino-2,4,6-triazina, es un herbicida que se utiliza para el control de malezas anuales y gramíneas perennes. Aunque este herbicida se encuentra prohibido en la Unión Europea por su toxicidad y la de sus metabolitos, sigue siendo muy usado y en Uruguay ocupa el segundo lugar de importancia. El principal mecanismo de eliminación de la atrazina en ambientes con pH neutro es la degradación bacteriana. Los microorganismos pueden mineralizar la atrazina dando amonio y anhídrido carbónico o degradarla produciendo intermediarios de variada persistencia y toxicidad. La separación y detección de estos intermediarios es relevante para conocer el riesgo sanitario que representa su degradación parcial en el ambiente y para encontrar y caracterizar bacterias o consorcios degradadores con potencial aplicación en bioorremediación. Entre los intermediarios de la biodegradación de atrazina se encuentran la hidroxiatrazina, la desetilhidroxiatrazina, la desisopropilhidrtoxiatrazina y el ácido cianúrico. En el presente trabajo se desarrolló un método para separar atrazina de sus metabolitos en un medio de cultivo sintético empleado para seleccionar bacterias degradadoras de atrazina. Para esto se optimizó una técnica de cromatografía líquida de alta performance (HPLC) de par iónico utilizando una columna C8, fase móvil acetonitrilo/agua, con un gradiente de flujo y detector UV. Se evaluó su aplicación para detectar intermediarios en varios enriquecimientos bacterianos degradadores de atrazina. Se pudo comprobar que el método resulta adecuado para distinguir capacidades metabólicas de enriquecimientos diferentes.Asociación de Universidades Grupo Montevide

Selection and characterization of bacterial consortium as a tool for bioremediation of atrazine contamination in water treatment plants

El uso expandido a nivel mundial, la persistencia y toxicidad del herbicida atrazina y sus metabolitos llevaron a que se conviertan en uno de los contaminantes más comunes en aguas superficiales y subterráneas, excediendo en algunos casos los límites máximos permitidos por la EPA de 3 ppb. A pesar que la atrazina puede ser degradada abióticamente, la biológica es la vía de degradación más importante a pH neutro y es la única que podría terminar en CO2 y NH4. La degradación biológica de la atrazina que puede llevarse a cabo por especies de bacterias aisladas como Pseudomonas sp. strain ADP o por consorcios de bacterias relativamente sencillos que fueron obtenidos de suelos con una historia larga de contaminación. En este estudio, el foco se centró en obtener consorcios de bacterias capaces de degradar atrazina en muestras tomadas del agua que ingresa a diferentes plantas potabilizadoras (Aguas Corrientes, Dolores y Florida) que estuvieron esporádicamente expuestos a pulsos de atrazina en bajas concentraciones. Se realizaron ensayos en microcosmos con atrazina a una concentración de 20 ppm con o sin el agregado de otra fuente de nitrógeno (NO3 -) y dos temperaturas de incubación diferentes (20°C y 30°C). La estabilidad del los consorcios se probó mediante repiques sucesivos en un medio mínimo (MDA) manteniendo las mismas condiciones previas. En todos los casos la degradación de atrazina se midió por UV-HPLC. Adicionalmente, se amplificaron por PCR los genes de la vía metabólica de degradación de la atrazina atzA, trzN, atzB, atzC, atzD and trzD para confirmar su presencia en los. Cuatro de doce tratamientos en el ensayo en microcosmos degradaron atrazina en un período de 11 días en Aguas Corrientes y Dolores. Las muestras de Florida no mostraron degradación de atrazina.The worldwide use, persistence, and toxicity of the herbicide atrazine and its metabolites have led to them becoming a common contaminant in surface and ground water at levels that sometimes exceed the maximum allowed by the US-EPA of 3 ppb. Although atrazine can be degraded abiotically, the biological is the most important at neutral pH and is the unique way that could degrade atrazine completely to NH4 and CO2. Atrazine biodegradation has previously been shown to be carried out by several individual bacterial species such as Pseudomonas sp. strain ADP or by relatively simple bacterial consortia that have been enriched from large history contaminated soils. This study was focused on obtaining stable microbial consortium capable of degrade atrazine taken from incoming water of different potabilization treatment plants from Uruguay (Aguas Corrientes, Dolores y Florida) that have sporadically been exposure to low pulses of atrazine. We prepared microcosms assays with atrazine at a concentration of 20 ppm with or without other inorganic nitrogen amendment (NO3 -) and two different incubation temperatures (20 °C and 30 °C). Stability of the bacterial consortium was tested by successive enrichment in an atrazine minimal medium (MDA) maintaining the same previous conditions. In all cases, atrazine degradation was monitored by UVHPLC. In addition, atrazine metabolic genes atzA, trzN, atzB, atzC, atzD and trzD were amplified by PCR to confirm genetic stability. Four of the twelve microcosms assays showed atrazine degradation in a period of 11 days at different incubation conditions from samples from Dolores and Aguas Corrientes. Florida did not show atrazine degradation activity.Asociación de Universidades Grupo Montevide

Physical, histological, endocrinological and steroidogenical evaluation of male cats postnatally exposed to sexual steroids

To test the hypothesis that postnatal sexual steroids induce an impairment of domestic male cat reproductive function, this study describes the physical, endocrine, steroidogenical and histological effects of a single, high dose of a postnatal sexual steroid in this species. Twenty male kittens were randomly assigned within the first 24 h of birth to: Testosterone enanthate 12.5 mg sc (TE; n = 8), medroxyprogesterone acetate 10 mg sc (MA; n = 6), or Placebo sc (PL; n = 6). The cats were followed until puberty when they were castrated. Kittens achieved puberty without age differences among groups (P > 0.05). Two MA cats presented abnormal testicular descent. Histological evaluation of the MA (P 0.05). It was concluded that the postnatal progestagen initially suppressed the gonadal axis and caused an impairment of spermatogenesis and testicular descent at puberty. Androgen treatment caused downregulation of the final steroidogenic cascade.Fil: Grisolia, M.. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Faya, Marcela Inés. Area de Ciencias Agrarias, Ingeniería, Ciencias Biológicas y de la Salud de la Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Marchetti, Cynthia Dayana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: López Merlo, Mariana Lucía. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: D Francisco, Florencia Alina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Bellini, Maria Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Gobello, María Cristina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Future Opportunities in Accelerator-based Neutrino Physics

International audienceThis document summarizes the conclusions of the Neutrino Town Meeting held at CERN in October 2018 to review the neutrino field at large with the aim of defining a strategy for accelerator-based neutrino physics in Europe. The importance of the field across its many complementary components is stressed. Recommendations are presented regarding the accelerator based neutrino physics, pertinent to the European Strategy for Particle Physics. We address in particular i) the role of CERN and its neutrino platform, ii) the importance of ancillary neutrino cross-section experiments, and iii) the capability of fixed target experiments as well as present and future high energy colliders to search for the possible manifestations of neutrino mass generation mechanisms