Rhodococcus: A promising genus of actinomycetes for the bioremediation of organic and inorganic contaminants.

Rhodococcus is a genus of actinomycetes that has been explored by the scientific community for different purposes, especially for bioremediation uses. However, the mechanisms governing Rhodococcus-mediated bioremediation processes are far from being fully elucidated. In this sense, this work aimed to compile the recent advances in the use of Rhodococcus for the bioremediation of organic and inorganic contaminants present in different environmental compartments. We reviewed the bioremediation capacity and mechanisms of Rhodococcus spp. in the treatment of polycyclic aromatic hydrocarbons, phenolic substances, emerging contaminants, heavy metals, and dyes given their human health risks and environmental concern. Different bioremediation techniques were discussed, including experimental conditions, treatment efficiencies, mechanisms, and degradation pathways. The use of Rhodococcus strains in the bioremediation of several compounds is a promising approach due to their features, primarily the presence of appropriate enzyme systems, which result in high decontamination efficiencies; but that vary according to experimental conditions. Besides, the genus Rhodococcus contains a small number of opportunistic species and pathogens, representing an advantage from the point of view of safety. Advances in analytical detection techniques and Molecular Biology have been collaborating to improve the understanding of the mechanisms and pathways involved in bioremediation processes. In the context of using Rhodococcus spp. as bioremediation agents, there is a need for more studies that 1) evaluate the role of these actinomycetes on a pilot and field scale; 2) use genetic engineering tools and consortia with other microorganisms to improve the bioremediation efficiency; and 3) isolate new Rhodococcus strains from environments with extreme and/or contaminated conditions aiming to explore their adaptive capabilities for bioremediation purposes.

Evaluación de riesgo a la salud y contaminantes en agua de bebida: Importancia de la ingesta de agua / Evaluation of health risk and contaminants in drinking water: Importance of the water intake

Se evaluó la importancia del consumo diario de agua por ingesta en la evaluación de riesgo a la salud humana (ERS) de contaminantes presentes en agua subterránea de pozos domiciliarios en la ciudad de Azul, Argentina. El riesgo probabilístico acumulativo se calculó en base al modelo de la Agencia de Protección Ambiental de Estados Unidos (USEPA) para cuatro grupos de edad (5, 10, 15 años y adultos). Los resultados fueron comparados mediante la aplicación de un consumo diario de agua por ingesta estimado utilizado con frecuencia en la literatura frente a una cantidad ingerida local. De las seis variables usadas (Concentración de la sustancia peligrosa en el agua; Ingesta diaria de agua (I); Frecuencia de exposición; Duración de la exposición; Peso corporal del individuo expuesto; Factor de corrección para el tiempo promedio de exposición crónica), la Ifue la variable más influyente en el va­lor del riesgo presentando diferencias significativas entre los resultados derivados de ambos tipos de I. La diferencia más alta fue en los 5 años de edad, grupo que presentó un riesgo acumulado asociado con I local 98% más bajo respecto del riesgo calculado utilizando I basada en la literatura. La selección de la I tuvo un impacto significativo en los resultados del riesgo, lo que sugiere una cuidadosa elección de las variables de entrada al modelo de la evaluación del riesgo para evitar subestimaciones o sobreestimaciones.

We evaluated the importance of the daily consumption of water by ingestion on health risk assessment (HRA) from pollutants present in shallow groundwater from residential wells in the city of Azul, Argentina. The probabilistic cumulative risk was calculated based on the model of the United States Environmental Protection Agency (USEPA) for four age groups (5, 10, 15 years and adults). The results were compared by applying a daily consumption of water by estimated intake frequently used in the literature against a local ingested amount. From the six variables used (Concentration of the hazardous substance in water, Daily water intake (I), Frequency of exposure, Duration of exposure, Body weight of the exposed individual, Correction factor for the average time of chronic exposure), I was the most influential variable in the value of risk, presenting significant differences between the results de­rived from both types of I. The highest difference was in the 5 years of age, a group that presented an accumulated risk associated with local I 98% lower regarding the risk calculated using I based on the literature. The selection of I had a significant impact on risk outcomes, suggesting a careful choice of input variables to the risk assessment model to avoid underestimation or overestimation.

Cell wall physicochemical properties determine the thallus biomineralization pattern of Padina gymnospora (Phaeophyceae).

Approximately half of the Padina (Dictyotales, Phaeophyceae) species mineralize aragonite needles over the adaxial thallus surface, where mineral bands are interspersed with nonmineralized regions along the thallus from the apical to basal end. However, this calcification pattern and the related algal properties are not well understood. Therefore, this work was performed to elucidate a potential role of cell walls in the inhibition/induction of mineralization in the brown alga Padina gymnospora. In a comparison of specific thallus regions, differences were identified in the cellulose distribution, microfibrils arrangement and thickness, distribution and abundance of phenolic substances, and physical differences among the surfaces of the thallus (deformation, adhesion, topography, and nano-rugosity). In vitro mineralization assays indicated that phenolic substances are strong modulators of calcium carbonate crystals growth. In addition, de novo mineralization assays over cell wall surfaces that were used as templates, even without cellular activity, indicated that the cell wall remains a key factor in the induction/inhibition of mineralization. Overall, the current findings indicate a strong correlation between the physico-chemical and structural properties of the cell wall and the alternation pattern of the mineralization bands over the thallus of P. gymnospora.

New propolis type from north-east Brazil: chemical composition, antioxidant activity and botanical origin.

BACKGROUND: Propolis is a bee product with wide diversity of biological activity. It has a complex composition, which is dependent on its botanical source. The present study aimed to determine the chemical profile, antioxidant activity and botanical origin of two samples of a propolis type from two locations of the state of Rio Grande do Norte (RN, north-east Brazil). RESULTS: The standard chemical characteristics of the RN propolis are similar or superior to the internationally marketed Brazilian green propolis. RN propolis from two locations have high antioxidant activity, corresponding to 10% (municipality of Afonso Bezerra) and 13% (municipality of Alto do Rodrigues) of quercetin activity by the 2,2-diphenyl-1-picrylhydrazyl method and to 15% (both locations) by the ß-carotene discoloration method. High-performance liquid chromatography with diode array detection (HPLC-DAD)-electrospray ionization-tandem mass spectrometry analyses revealed that most constituents of the RN propolis are flavonoids, mainly flavonols and chalcones. HPLC-DAD analysis of ethanol extracts revealed a great similarity between the chemical profile of RN propolis and shoot apices of 'jurema-preta' (Mimosa tenuiflora, Leguminosae, Mimosoideae). CONCLUSION: 'Jurema-preta' shoot apices are likely resin sources of RN propolis. The chemical characteristics and antioxidant property of RN propolis provide promising prospects for the introduction of this type of propolis into the apicultural market. © 2017 Society of Chemical Industry.