Biodegradation of Certain Petroleum Product Contaminants in Soil and Water By Selected Bacteria

Soil contamination by gasoline underground storage tanks is a critical environmental problem. The results herein show that in situ bioremediation using indigenous soil microorganisms is the method of choice. Five sites were selected for bioremediation based on the levels of benzene, toluene, ethylbenzene and xylene and the amount of total petroleum hydrocarbons in the soil. Bacteria capable of degrading these contaminants were selected from the contaminated sites and grown in 1,200 I mass cultures. These were added to the soil together with nutrients, water and air via PVC pipes

Editorial: microbiological risks in food processing

info:eu-repo/semantics/publishedVersio

Las pruebas de diferencia en el análisis sensorial de los alimentos

La evaluación sensorial de alimentos es de suma importancia en la investigación y el desarrollo de alimentos. El tipo de análisis sensorial dependerá del tipo de información requerida, y en este sentido, el presente artículo provee un panorama de las estrategias utilizadas en pruebas de diferencia, que se utilizan cuando se desea conocer si dos alimentos son perceptiblemente distintos. Las pruebas de diferencia son ampliamente usadas tanto en la academia como en la industria, con aplicaciones en el control de calidad, el estudio del impacto por cambios en la formulación o el proceso, la habilidad de los consumidores para discriminar entre dos productos similares, entre otras aplicaciones. Primero, se presenta una revisión de las pruebas discriminativas, haciendo énfasis en los diferentes tipos de pruebas, para luego describir las teorías de análisis estadístico de resultados, describiendo especialmente, los diversos problemas que se presentan en este tipo de pruebas. Finalmente, se presenta la modelación Thurstoniana que puede ser usada para obtener información, considerando el procesamiento central en el cerebro. La consideración de todas estas variables permitirá la selección del protocolo más adecuado en investigaciones de evaluación sensorial con este tipo de pruebas. Abstract Food sensorial analysis is an important area in research and development of new food alternatives. The type of sensorial analysis used, will depend on the type of information required; in this sense, this article contains a panoramic view of some difference tests, which are used to determine if there are perceptible differences among two food sample. These tests are widely used both in academy and industry, in applications such as food process quality control, evaluation of the impact on changes in food process or formulation, as well as for the ability of consumers to distinguish between two similar products, among other applications. First, there is a revision of discriminative tests, emphasizing on the different test included; then, the descriptions of the theories of analysis of results are included, especially describing the problems related to those analyses. Finally, the Thurstonian modeling is explained, that can be used to obtain information, considering the central processing of information that is carried out in the brain. The consideration of all the above variables, will allow select the most appropriate protocol for the type of sensorial analysis required in a particular food analysis Keywords: Sensorial analysis, statistical tests, difference test

Biosurfactants as Useful Tools in Bioremediation

Environmental pollution by organic contaminants is a major problem today because it has affected many environments. Hydrophobic contaminants are of special concern since their molecules can be bound to the soil particles, but because of its low solubility in water and high interfacial tension, those contaminants cannot be easily removed. To help with desorption of contaminants, surfactants can be used in soil and water remediation technologies. Amphiphiles that can form micelles are termed as surface active agents or surfactants and are among the most commonly used chemicals in everyday life. Chemically produced surfactants have increasingly been replaced by biotechnology-based products, obtained either by enzymatic or microbial synthesis, because they can be produced using natural resources. The group of surface active biomolecules produced by living organism is called biosurfactants. Originally, biosurfactants attracted attention as hydrocarbon-dissolving agents in the late 1960s and as potential replacements for synthetic surfactants (carboxylates, sulfonates and sulfate acid esters) in the food, pharmaceutical, and oil industries. Synthetic surfactants currently used are usually toxic and hardly degraded and as such are also a contaminant in the environment. To replace synthetic surfactants, biosurfactant production needs to be cost-effective; therefore, it is important to develop culture conditions with low-cost materials using efficient biosurfactant-producing microbial strains. Although bacteria have been extensively studied for biosurfactant production, yeasts are also potential biosurfactant-producing microorganisms. Because of their unique structures, biosurfactants may have a greater range of properties that can be exploited commercially. This review article will describe microorganisms related to biosurfactant production, including yeasts, as well as their role in bioremediation

El papel de los antimicrobianos en la estructura de las comunidades microbianas en la naturaleza

Los microambientes son estructuras complejas, en donde se encuentran en equilibrio una gran cantidad de organismos microscópicos, tanto eucariotes como procariotes, que interaccionan entre ellos y con los factores abióticos del medio. Para lograr el equilibrio entre los miembros de una comunidad microbiana, se establecen interacciones que resultan benéficas o perjudiciales para una de las especies que interaccionan, o para ambas. Entre estas interacciones, se encuentran: comensalismo, simbiosis, y parasitismo, entre otras. Estas interacciones les facilita a los microorganismos la obtención de compuestos que pueden ser utilizados como substratos o como complementos, asegurando así su sobrevivencia y mantenimiento en un ecosistema. Para sobrevivir, algunos microorganismos deben producir compuestos capaces de inhibir el desarrollo de microorganismos competidores. Estos compuestos, conocidos como antimicrobianos, pueden causar daño a la célula bacteriana competidora a través de diversos mecanismos de acción, pero el fin es cumplir con el mismo objetivo, la eliminación de la competencia microbiana. La producción industrial de algunos de estos antimicrobianos, han revolucionado nuestra forma de vida, al proporcionarnos herramientas para el control de enfermedades infecciosas. Abstract Microenvironments are natural complex structures, where microscopic organisms (both, eukaryotic and prokaryotic organisms) are in balance, by way of interactions among them and with the abiotic factors present in the environment. In order to achieve equilibrium between the members of a microbial community, different interactions are established, that are either beneficial or prejudicial to one or both interaction species. Among those interactions are commensalism, symbiosis and parasitism. The interactions support the acquirement of compounds that can be used as substrates or complements for microbial growth, assuring in this way, its survival and maintenance in the ecosystem. To survive, some microorganisms produce compounds capable of inhibiting the development of competitive microbiota. Those compounds, known as antimicrobials, can cause damage to the competitive microbial cell through different mechanisms of action, but the final goal is the same: to eliminate the competitive microbiota. Industrial production of some of those antimicrobials, have revolutionized our society, since they can be used to control infectious diseases. Keywords: microbial interactions, symbiosis, parasitism, competition, bacteria

Experimental and quantum chemical studies of a novel synthetic prenylated chalcone

BACKGROUND: Chalcones are ubiquitous natural compounds with a wide variety of reported biological activities, including antitumoral, antiviral and antimicrobial effects. Furthermore, chalcones are being studied for its potential use in organic electroluminescent devices; therefore the description of their spectroscopic properties is important to elucidate the structure of these molecules. One of the main techniques available for structure elucidation is the use of Nuclear Magnetic Resonance Spectroscopy (NMR). Accordingly, the prediction of the NMR spectra in this kind of molecules is necessary to gather information about the influence of substituents on their spectra. RESULTS: A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical (1)H-NMR and (13)C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X) levels of theory in combination with a 6-311++G(d,p) basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p), whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO) formalism in a DFT:M06-2X/6-311++G(d,p) optimized geometry. CONCLUSION: Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of (1)H-NMR and (13)C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of substituted chalcones with good correlation with the experimental data

Materiales de soporte para el crecimiento de biopelícula en un reactor de lecho fluidizado

Se evaluó el efecto de materiales de soporte de baja densidad sobre la eficiencia de un reactor de lecho fluidizado para el tratamiento de aguas residuales. Primero se seleccionaron varios materiales de origen mineral, con densidad específica menor que la densidad de la arena sílica. Después se evaluaron otros materiales porosos de densidad específica ligeramente menor a la densidad de la arena sílica, pero con una densidad aparente significativamente menor. De un total de 10 materiales evaluados, sobresalieron la mezcla de poliéster-perlita expandida y la perlita vitrificada como los mejores materiales. La fluidización del lecho de poliéster-perlita se obtuvo con una velocidad de recirculación de 0.45 y la de perlita vitrificada con 0.55 cm seg-1. Ambas velocidades de recirculación son menores a las reportadas para materiales de densidad similar. El régimen de fluidización favoreció la operación del reactor en forma continua sin la necesidad de aplicar lavados del lecho y sin llegar a la saturación del mismo. DOI: https://doi.org/10.54167/tecnociencia.v2i2.7

Consumo responsable de la tortilla de maíz, una herencia que debemos cuidar

México es centro de origen del maíz, que se encuentra muy relacionado con las cosmovisiones de las culturas originales del país. Aun hoy en día, en el México rural se conserva la producción de maíz en la tradicional Milpa, en donde también se cosechan otros productos alimenticios de alto valor nutritivo. La tortilla es un producto de maíz con presencia casi universal en los hogares mexicanos. La forma tradicional de preparación de tortillas ha sido modificada para aumentar su producción, y hoy en día se pueden encontrar tanto tortillas elaboradas de manera tradicional, como industrial. También existen variedades de tortilla dependiendo del maíz utilizado, así como del propósito de su elaboración. Ante los retos del desarrollo sostenible, en donde la generación de desperdicios de alimentos está inscrito en una de las metas de los Objetivos del Desarrollo Sostenible, deben promoverse estrategias de concientización para la disminución de desperdicios alimenticios generados. El desperdicio de tortillas de maíz, puede utilizarse como indicador del grado de generación de residuos, y como ejemplo de un consumo responsable de alimentos

Laboratory-Scale Biodegradation of Fuel Oil No. 6 in Contaminated Soils by Autochthonous Bacteria

In order to evaluate the degradation of fuel oil no. 6 (FO6) in contaminated soil, laboratory-scale bioreactors were set up to study biostimulation, bioaugmentation, and natural attenuation processes. A solution of fertilizers was added in biostimulation and biouagmentation (0.03% N, 0.01% P). To the bioaugmentation process, an enrichment culture of indigenous hydrocarbon-degrading microorganisms was also added once a week. Total aerobic and hydrocarbon-degrading microorganisms were determined by plate count, and total petroleum hydrocarbon (TPH) concentration was determined gravimetrically (EPA method 9071b) every 15 days. After 1 year of study, degradation rate was higher for biostimulation (0.19 g TPH/day), followed by natural attenuation (0.18 g TPH/day) and bioaugmentation (0.16 g TPH/day). TPH showed a change in composition of hydrocarbons, attributed to microbiological activity. Microbial counts of hydrocarbon-degrading microorganisms were on the range of 4–6 log CFU/g soil. Preliminary bacterial identification corresponded to Pseudomonas, Rhodococcus, Actinomyces, and Bacillus strains; randomly amplified polymorphic DNA (RAPD); and denaturing gradient gel electrophoresis (DGGE) analysis demonstrated a large microbial diversity. From the degradation rates, it can be predicted that such limits will be achieved by increasing further 107–117 days of the treatments. Results demonstrated to be efficient on the restoration of contaminated soil, being an alternative to treat soils contaminated with heavy hydrocarbons