BackgroundCyanide is one of the most toxic chemicals produced by anthropogenic activities like mining and jewelry industries, which generate wastewater residues with high concentrations of this compound. Pseudomonas pseudoalcaligenes CECT5344 is a model microorganism to be used in detoxification of industrial wastewaters containing not only free cyanide (CN−) but also cyano-derivatives, such as cyanate, nitriles and metal-cyanide complexes. Previous in silico analyses suggested the existence of genes putatively involved in metabolism of short chain length (scl-) and medium chain length (mcl-) polyhydroxyalkanoates (PHAs) located in three different clusters in the genome of this bacterium. PHAs are polyesters considered as an alternative of petroleum-based plastics. Strategies to optimize the bioremediation process in terms of reducing the cost of the production medium are required.ResultsIn this work, a biological treatment of the jewelry industry cyanide-rich wastewater coupled to PHAs production as by-product has been considered. The functionality of the pha genes from P. pseudoalcaligenes CECT5344 has been demonstrated. Mutant strains defective in each proposed PHA synthases coding genes (Mpha−, deleted in putative mcl-PHA synthases; Spha−, deleted in the putative scl-PHA synthase) were generated. The accumulation and monomer composition of scl- or mcl-PHAs in wild type and mutant strains were confirmed by gas chromatography-mass spectrometry (GC–MS). The production of PHAs as by-product while degrading cyanide from the jewelry industry wastewater was analyzed in batch reactor in each strain. The wild type and the mutant strains grew at similar rates when using octanoate as the carbon source and cyanide as the sole nitrogen source. When cyanide was depleted from the medium, both scl-PHAs and mcl-PHAs were detected in the wild-type strain, whereas scl-PHAs or mcl-PHAs were accumulated in Mpha− and Spha−, respectively. The scl-PHAs were identified as homopolymers of 3-hydroxybutyrate and the mcl-PHAs were composed of 3-hydroxyoctanoate and 3-hydroxyhexanoate monomers.ConclusionsThese results demonstrated, as proof of concept, that talented strains such as P. pseudoalcaligenes might be applied in bioremediation of industrial residues containing cyanide, while concomitantly generate by-products like polyhydroxyalkanoates. A customized optimization of the target bioremediation process is required to gain benefits of this type of approaches.
The thermal response of soils in cold environments has been investigated in numerous studies. The data considered here were obtained in a study carried out in Tierra del Fuego, Argentina, as part of the IV International Polar Year. Temperature sensors were installed at ground level (0) and depths of -10, -20 and -60 cm in the study area, with the aim of characterizing the thermal response by detecting diurnal and annual variations.The study has two main aims. The first is to present and discuss the study findings regarding the thermal response of a soil in a sub-Antarctic environment by using classical descriptive analysis. The second, closely related, aim is to apply some novel statistical tools that would help improve this description. The study of freeze-thaw patterns can be approached from a non-parametric perspective, while taking into account the cyclical nature of the data. Data are considered cyclical when they can be represented on a unit circle, as with the hours in which certain events occur throughout a day (e.g. freezing and thawing). Analysis of this type of data is very different from the analysis of scalar data, as regards both descriptive and graphical measures. The application in this study of methods used to represent and analyse cyclical data improved visualization of the data and interpretation of the analytical findings. The main contribution of the present study is the use of estimators of the nuclear type density and derived techniques, such as the CircSiZer map, which enabled identification of significant freeze-thaw patterns. In addition, the relationships between the temperature recordings at different points were analysed using Taylor diagrams.
RESUMEN: La Biotecnología ambiental trata de corregir los desequilibrios causados en el medio ambiente por actividades industriales que alteran los ecosistemas naturales mediante contaminación química o biológica y que también afectan a los grandes ciclos biogeoquímicos en la biosfera, mayoritariamente catalizados por seres vivos, entre los que los microrganismos juegan un papel esencial. Las desviaciones en los balances de compuestos carbonados, nitrogenados y azufrados atmosféricos pueden causar fenómenos de gran complejidad como el calentamiento global, la destrucción de la capa de ozono, la contaminación ambiental o la lluvia ácida. Por otra parte, las interacciones de los microorganismos entre sí y con el medio, desconocidas en su mayor parte, tiene importantes repercusiones en la generación y persistencia de especies químicas que, depositadas en las cadenas tróficas, son altamente tóxicas para los organismos vivos. Para atajar estos problemas es necesario avanzar en el conocimiento a nivel molecular de la ecología microbiana y del funcionamiento de los ciclos biogeoquímicos, aunque no es menos necesario desarrollar tecnologías para la eliminación de contaminantes industriales in situ y ex situ, evitar su producción y utilización incontroladas así como corregir las actuaciones desequilibrantes, actuales o futuras, de la biogeoquímica planetaria.
Resumen: En este trabajo se aborda el estudio de la estacionalidad luviométrica en Galicia or medio de un índice sencillo, IE, propuesto por Wakh y Lawler (1983). E; Rnción de los valores medios que toma el índice puede decirse que la lluvia en Galicia presenta patrones de distribución con estacionalidad moderada a fuerte. Siendo las áreas interiores de las rías atlánticas, ciertos sectores con efecto quilla y los valles de los ríos orientales y surorientales, aquellos donde se manifiesta el mayor grado de estacionalidad. Sin embargo, el análisis de las series de precipitación para cada estación, revela que en la mayor parte del territorio ha habido años con niveles que van desde la estacionalidad débil a la concentración moderada. En base a la frecuencia de años en cada clase del IE, se han agrupado las estaciones mediante un análisis de asociación, comprobando la validez de los ru os definidos por medio de un análisis discriminante. Eso nos ha permiti f o f ' a cartografía de los distintos sectores geográficos de estacionalidad pluviométrica. Finalmente, se describen las relaciones entre las variaciones de la estacionalidad y los valores medios de recipitación anual, de invierno, verano, primavera y otoño. Haciendo referencia a Pos mecanismos climáticos que pueden estar implicados. Palabras clave: Galicia, estacionalidad pluviométrica, IE (Walsh y Lawler).Abstract: Seasonality of rainfall in Galicia (NW Spain) is studied by means of a simple index propossed b Walsh & Lawler (1983). Average values of the index for the 180 meteorologica?stations studied, indicate that rainfall has distribution patterns ranging from moderate to strong seasonality. Inner areas of the Atlqntic Galician Rias, some sectors with cape effect and the valleys of eastern and soutlieastern rivers are the ones with the gratest de ree of seasonality.Nevertheless, a detailed analysis of rainfall series f or each meteorological station, reveals that almost al1 the region has experienced years with rainfall oing from weak seasonality to moderate concentration, being strong a n f extreme concentration unfrequent. Usin the frequence of each d e r o f , seasonality a cl~isirr analysis was performe$ and corroborated by a iscriminant analysis, defining five principal groups. These groups are mapped.
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