Isolation and identification of metallotolerant bacteria with a potential biotechnological application.

Mining has led to severe environmental pollution in countries with exhaustive mining production and inadequate industrial waste regulation. Microorganisms in contaminated sites, like mine tailings, have adapted to high concentrations of heavy metals, developing the capacity of reducing or removing them from these environments. Therefore, it is essential to thoroughly characterize bacteria present in these sites to find different ways of bioremediation. In this regard, in this study, an enrichment and isolation procedure were performed to isolate bacteria with lower nutritional requirements and high tolerance to Cu(II) and Fe(II) from two Sonoran River basin mining tails. Two Staphylococcus species and a Microbacterium ginsengisoli strain were isolated and identified from the San Felipe de Jesús mining tail. Also, three strains were isolated from the Nacozari de García mining tail: Burkholderia cenocepacia, Sphingomonas sp. and Staphylococcus warneri. Significant microbiological differences were found between the two sites. All these species exhibited tolerance up to 300 mg/L for Cu (II)-Fe (II) solutions, indicating their capacity to grow in these conditions. Moreover, a consortium of isolated bacteria was immobilized in two different biocomposites and the biocomposite with larger pore size achieved greater bacterial immobilization showcasing the potential of these bacteria in biotechnological applications.

Biochemical and Molecular Aspects of Phosphorus Limitation in Diatoms and Their Relationship with Biomolecule Accumulation.

Diatoms are the most abundant group of phytoplankton, and their success lies in their significant adaptation ability to stress conditions, such as nutrient limitation. Phosphorus (P) is a key nutrient involved in the transfer of energy and the synthesis of several cellular components. Molecular and biochemical mechanisms related to how diatoms cope with P deficiency are not clear, and research into this has been limited to a few species. Among the molecular responses that have been reported in diatoms cultured under P deficient conditions is the upregulation of genes encoding enzymes related to the transport, assimilation, remobilization and recycling of this nutrient. Regarding biochemical responses, due to the reduction of the requirements for carbon structures for the synthesis of proteins and phospholipids, more CO2 is fixed than is consumed by the Calvin cycle. To deal with this excess, diatoms redirect the carbon flow toward the synthesis of storage compounds such as triacylglycerides and carbohydrates, which are excreted as extracellular polymeric substances. This review aimed to gather all current knowledge regarding the biochemical and molecular mechanisms of diatoms related to managing P deficiency in order to provide a wider insight into and understanding of their responses, as well as the metabolic pathways affected by the limitation of this nutrient.

Determination of Chemical Constituents and Antioxidant Activities of Leaves and Stems from Jatropha cinerea (Ortega) Müll. Arg and Jatropha cordata (Ortega) Müll. Arg.

Jatropha species have been shown to be an important source of secondary metabolites with different biological effects. Jatropha cinerea (Ortega) Müll. Arg and Jatropha cordata (Ortega) Müll. Arg are distributed in the Northwestern region of Mexico, are adapted to extreme weather conditions and are widely used (stems, leaves, and sap) in traditional medicine. The aim of the present study was to carry out the phytochemical characterization and the evaluation of the antioxidant activity in methanolic extracts of stems and leaves from J. cinerea and J. cordata. The compounds present in the extracts of both species were characterized by ESI-IT-MS/MS and quantified by HPLC-DAD. The results showed that the stem extracts of both species are rich in phenolic acids, while the leaf extracts are rich in flavonoids. Some of the main compounds found were gallic acid, gentisic acid, 3,4-Dihydroxybenzoic acid, vitexin, isovitexin, and catechol. Both species showed high concentrations of phenols and total flavonoids and antioxidant activity. J.cordata showed the highest antioxidant capacity and the highest concentration of phenolic compounds. Overall, both Jatropha species are a natural source of antioxidant compounds with potential biotechnological uses.

A novel process of the isolation of nitrifying bacteria and their development in two different natural lab-scale packed-bed bioreactors for trichloroethylene bioremediation.

Trichloroethylene (TCE) is a carcinogenic compound that is commonly present in groundwater and has been detected in drinking water sources for Mexican towns in the Mexico-US border area. Nitrifying bacteria, such as Nitrosomonas europaea, have been shown to be capable of degrading halogenated compounds, including TCE, but it is difficult to obtain high cell concentrations of these bacteria. The aim of the present study was to generate biomass of a nitrifying bacterial consortium from the sludge of an urban wastewater treatment plant (WWTP) and evaluate its capacity to biodegrade TCE in two different natural lab-scaled packed bed bioreactors. The consortium was isolated by a novel method using a continuous stirred-tank bioreactor inoculated with activated sludge from the Domos WWTP located in Cd. Obregón, Sonora, Mexico. The bioreactor was fed with specific media to cultivate ammonia-oxidizing bacteria at a dilution rate near the maximum specific growth rate reported for Nitrosomonas europaea. Optical density and suspended solids measurements were performed to determine the culture biomass production, and the presence of inorganic nitrogen species was determined by spectrophotometry. The presence of nitrifying ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was confirmed by PCR amplification, and biofilm formation was observed by scanning electron microscopy. Batch-scale experiments confirmed the biodegradative activity of the isolated consortium, which was subsequently fixed in an inorganic carrier as zeolite and a synthetic carrier such as polyurethane to both be used as lab-scale packed-bed bioreactors, with up to 58.63% and 62.7% of TCE biodegradation achieved, respectively, demonstrating a possible alternative for TCE bioremediation in environmental and engineering systems.

Effect of frying and storage on oxidative quality of conjugated linoleic-acid-rich soybean oil produced by photoisomerization using plantain as a model system.

BACKGROUND: Conjugated linoleic acid (CLA) is known to have beneficial properties to health. Naturally, in foods it is found in very low concentrations, and so these beneficial properties cannot be obtained. This study investigated the enrichment of soybean oil by photoisomerization, as well as assessing its oxidative stability during the frying process using plantain slices as a model system and after a storage period of 20 days at 60 °C. RESULTS: The oxidative stability of soybean oil enriched with CLA by photoirradiation was measured based on the peroxide, p-anisidine, and Totox values, as well as by the polyphenol content, tocopherol content and DPPH· scavenging capacity. The results obtained showed that a substantial amount of CLA was obtained by photoirradiation (31.73%). The oxidative stability values of the oil enriched with CLA showed good stability during a frying cycle; however, this stability decreased when it was stored and during the final frying cycles. CONCLUSIONS: The results obtained indicated that photoirradiation is a good technique for obtaining oils enriched with CLA, and in this way CLA can be incorporated into foods; however, it is necessary to add antioxidants to improve their stability. © 2019 Society of Chemical Industry.

Lignin and holocellulose from pecan nutshell as reinforcing fillers in poly (lactic acid) biocomposites.

Lignocellulose from agro-food biowaste represents a valuable source of cost-effective structural fillers for wholly renewable polymer composites. In this work, pecan (Carya illinoinensis) nutshell (NS) fiber and its structural components, holocellulose (HC) and acid insoluble lignin (AIL), were isolated, characterized and used as reinforcing fillers to manufacture poly(lactic acid) (PLA) based biocomposites. Thermal, morphological and mechanical properties of the prepared materials were analyzed. NS and HC acted as heterogeneous nucleating agents, potentially able to control PLA physical aging. Moreover, they significantly enhanced the viscoelastic response of PLA, mainly restricting the melt molecular mobility due to hydrodynamic effects and the formation of a three-dimensional particulate network. Flexural tests demonstrated that HC induced a 25% increase in modulus compared to the plain polymer. AIL, conversely, conferred higher ductility to the PLA matrix producing an increase in stress and strain at break of 55% and 65%, respectively. Finally, all the biocomposites showed lower resilience with respect to plain PLA due to the lack of chemical adhesion between filler and matrix. These results emphasize the potential of NS as a source of reinforcing filler in polymer-based biocomposites.

Simulated Gastrointestinal Digestion, Bioaccessibility and Antioxidant Capacity of Polyphenols from Red Chiltepin (Capsicum annuum L. Var. glabriusculum) Grown in Northwest Mexico.

Chiltepin, a wild chili mostly used in different traditional foods and traditional medicine in Northwest Mexico, represents a source of polyphenols. However, studies about the bioaccessibility of polyphenols as a parameter to measure the nutritional quality and bioefficacy of them in the fruit after consumption are scarce. Chiltepin showed phenolic acids and flavonoids contents between 387 and 65 µg/g, respectively. Nevertheless, these values decreased after the digestion process. Before digestion, gallic acid, 4-hydroxibenzoinc acid, chlorogenic acid, caffeic acid, p-coumaric acid, quercetin and luteolin were the main polyphenols found in chiltepin by HPLC-DAD and confirmed by FIA-ESI-IT-MS/MS. Gallic and chlorogenic acids were non-detected in the gastric phase, while only p-coumaric acid (5.35 ± 3.89 µg/g), quercetin (5.91 ± 0.92 µg/g) and luteolin (2.86 ± 0.62 µg/g) were found in the intestinal phase. The bioaccessibility of phenolic acids, flavonoids, and total polyphenols after the intestinal phase was around 24, 17 and 23%, respectively. Overall, results indicated that release of polyphenols from chiltepin fruit might be affected by the food matrix and gastrointestinal conditions due to the low bioaccessibility values observed.

Expression analysis of genes involved in the synthesis of oleic and linoleic acids in Jatropha cinerea seeds from Northwestern Mexico / Análise de expressão de genes envolvidos na síntese de ácidos oleico e linoleico em sementes de Jatropha cinerea do noroeste do México

ABSTRACT: Plants belonging to genus Jatropha has arisen interest because of its high oil content that could be used to produce biodiesel. It is also widely reported that the main fatty acids in Jatropha oilseed are oleic and linoleic acids. However, there are scarce studies related to native species of Jatropha from Northwestern Mexico which are adapted to arid conditions, and the expression of genes involved in fatty acid synthesis for these species is still unknown. Therefore, the aim of this study was to analyze the expression of five genes, ACP1, KASII, D9SD, FAD2-1 and FAD2-2, which are involved in the oleic and linoleic acids synthesis in mature wild-seeds of Jatropha cinerea, a native species from Sonoran Desert, using semi-quantitative RT-PCR. The J. cinerea seeds were randomly collected in Bahía de Kino, Sonora (México) which is a region characterized by its harsh environments such as saline soils and extreme temperature changes and J. curcas mature seeds from a non-toxic variety from Veracruz, Mexico were used as a reference. The RT-PCR analysis of three biological replicates were considered to ensure data consistent. Our analysis showed a higher expression of KASII and FAD2-1 genes in J. cinerea seeds compared to J. curcas, meanwhile the expression of ACP1, D9SD and FAD2-2 were higher in J. curcas. Furthermore, Actin and FAD2-1 genes sequences here obtained are the first reported for J. cinerea, thus providing information to develop further studies.

RESUMO: Plantas pertencentes ao gênero Jatropha têm despertado interesse devido ao seu alto teor de óleo que poderia ser usado para produzir biodiesel. Também é amplamente relatado que os principais ácidos graxos das oleaginosas da Jatropha são os ácidos oléico e linoleico. No entanto, existem poucos estudos relacionados a espécies nativas de pinhão-manso do noroeste do México que estão adaptados a condições áridas, e a expressão de genes envolvidos na síntese de ácidos graxos para essas espécies ainda é desconhecida. Portanto, o objetivo deste estudo foi analisar a expressão de cinco genes, ACP1, KASII, D9SD, FAD2-1 e FAD2-2, que estão envolvidos na síntese de ácidos oleico e linoleico em sementes selvagens maduras de Jatropha cinerea, espécies nativas do Deserto de Sonora, usando RT-PCR semi-quantitativa. Sementes de J. cinerea foram coletadas aleatoriamente em Bahía de Kino, Sonora (México), região caracterizada por ambientes agressivos como solos salinos e mudanças extremas de temperatura, e sementes de J. curcas maduras de uma variedade não-tóxica de Veracruz, México, usado como referência. Análise RT-PCR de três repetições biológicas foram consideradas para garantir dados consistentes. Nossa análise mostrou uma maior expressão dos genes KASII e FAD2-1 em sementes de J. cinerea comparado a J. curcas, enquanto a expressão de ACP1, D9SD e FAD2-2 foi maior em J. curcas. Além disso, as sequências dos genes Actin e FAD2-1 obtidas são as primeiras relatadas para J. cinerea, fornecendo, assim, informações para o desenvolvimento de novos estudos.

Drying and pickling on phenols, capsaicinoids, and free radical-scavenging activity in Anaheim and Jalapeño peppers / Secagem e conserva sobre os fenóis, capsaicinoides e neutralização de radicais livres em pimentas Anaheim e Jalapeño

ABSTRACT: The effects of sun-drying, air-drying and pickling processes on phenol and capsaicinoid contents, and free radical-scavenging activity [2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2′-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid (ABTS)] in Anaheim (red) and Jalapeño peppers were evaluated. Sun-drying process in Anaheim pepper caused the highest phenols retention (100%), and the free radical-scavenging activity (100%) when compared with air-drying (80%). Pickling process in Jalapeño pepper caused a moderate reduction on the phenol content (24%) and the radical-scavenging activity by DPPH (35%). Processes studied did not cause variations in the capsaicinoid fractions neither in its radical-scavenging activity. Results suggested that dried and pickled peppers are a good source of phenolics and capsaicinoids with antioxidant activity.

RESUMO: Os efeitos dos processos de secagem ao sol, secagem ao ar e conserva sobre o conteúdo dos fenóis e capsaicinoides, assim como a atividade de eliminação de radicais livres [2,2-difenil-1-picrilhidrazilo (DPPH), e ácido 2, 2'-azino-bis 3-etilbenztiazolino-6-sulfónico ABTS)] em pimentas Anaheim (vermelho) e Jalapeño foram avaliados. A secagem ao sol mostrou maior retenção de fenóis (100%) e atividade de eliminação dos radicais livres (100%) quando foi comparada com a secagem ao ar (80%). O processo de conserva mostrou uma redução moderada no teor de fenóis (24%) e na capacidade de remoção de radicais (35%). Os processos estudados não causaram alterações nas frações capsaicinoides nem na seu atividade de eliminação de radicais. Os resultados sugerem que as pimentas secas e em conserva são uma boa fonte de fenóis e capsaicinoides com atividade antioxidante.

Antiproliferative and apoptotic activities of extracts of Asclepias subulata.

CONTEXT: Asclepias subulata Decne. (Apocynaceae) is a shrub used in the Mexican traditional medicine for the treatment of cancer. OBJECTIVE: The objective of this study was to evaluate the antiproliferative activity of methanol extract of aerial parts of A. subulata and its fractions against different cancer cell lines. Additionally, we analyzed the mechanism of action of the active fractions. MATERIALS AND METHODS: Methanol extract fractions were prepared by serial extraction with n-hexane, ethyl acetate, and ethanol. The antiproliferative activity of methanol extract and its fractions was evaluated, against several murine (M12.C3.F6, RAW 264.7, and L929) and human (HeLa, A549, PC-3, LS 180, and ARPE-19) cell lines by the MTT assay, using concentrations of 0.4-400 µg/mL for 48 h. Ethanol and residual fractions were separated using silica gel column. Apoptosis induction of cancer cells was evaluated by Annexin and JC-1 staining using flow cytometry. RESULTS: Methanol extract and its fractions showed antiproliferative activity against all human cancer cell lines tested. Methanol extract had the highest antiproliferative activity on A549 and HeLa cells (IC50 values < 0.4 and 8.7 µg/mL, respectively). Ethanol and residual fractions exerted significant antiproliferative effect on A549 (IC50 < 0.4 µg/mL) and PC3 cells (IC50 1.4 and 5.1 µg/mL). Apoptotic assays showed that CEF7, CEF9, CRF6, and CRF5 fractions induced mitochondrial depolarization in A549 cells, 70, 73, 77, and 80%, respectively. Those fractions triggered the apoptosis mitochondrial pathway. CONCLUSION: Our data show that A. subulata extracts have potent antiproliferative properties on human cancer cell lines. This plant should be considered an important source of potent anticancer compounds.

Total mercury in liver and muscle tissue of two coastal sharks from the northwest of Mexico.

Total mercury (THg) in liver and muscle of three costal sharks from Mexico were evaluated. The highest concentrations of THg in muscle tissue of juveniles were found in Sphyrna lewini (0.82 ± 0.33 mg kg(-1) wet basis). Rhizoprionodon longurio adults had the highest concentrations (0.92 ± 1.03 mg kg(-1)). THg concentrations in liver were low compared to those found in muscle tissue; higher levels were found in liver of juvenile S. lewini (0.250 ± 0.07 mg kg(-1)). Results showed that 35 % of muscle tissue samples are above the precautionary limit (0.50 mg kg(-1) of THg) and a 7 % exceeded the maximum limit for human consumption (1 mg kg(-1)).

Eliminación de compuestos toxicos, evaluación biologica y caracterización parcial de la proteina de pasta de jojoba (Simmonndsia chinensis) [Link] Schneider) / Elimination of toxic compunds, biological evaluation and partial characterization of the protein from jojoba meal (Simmondsia chinensis [Link] Schneider)

El objetivo principal de este trabajo fue el establecimiento de una metodología para destoxificar la pasta y harina de jojoba (Simmondsia chinensis (Link) Scheneider), su evaluación biológica y caracterización parcial de la proteína. Para la experimentación se utilizó pasta residual y semilla sin testa de jojoba; estos materiales fueron desengrasados con hexano y destoxificados con una mezcla de isopropanol-agua (7.3). Los productos destoxificados fueron evaluados por el método de la NPR para determinar el valor nutritivo de la proteína. La socución destoxificadora eliminó el 86% de los compuestos fenólicos y totalmente a las simmondsinas responsables del efecto letal y amargo que tiene la semilla completa o la pasta residual para los animales de laboratorio. Los productos destoxificados, incorporados a las dietas para ratas, mostraron que no sólo hubo sobrevivencia de los animales a lo largo de los 12 días de experimentación, sino incluso ganancia en peso. Sin embargo, los valores de NPR fueron significativamente diferentes a los de caseína (P < 0.05). De las fracciones proteínicas aisladas de la harina destoxificada de jojoba, el 61.8% representó a la fracción acuosa soluble, el 22.6% a la fracción salina soluble, y la alcalina fue de 14.6%. Las curvas de solubilidad de nitrógeno para estas fracciones mostraron que en la región de pH 3.0 se presentaba el putno isoelétrico (pl) para las proteínas acuosas y salino-solubles y un PI para la alcalino-soluble de 4.5 a 5.0, y el pH ...