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Inactivation of the transcription factor mig1 (YGL035C) in Saccharomyces cerevisiae improves tolerance towards monocarboxylic weak acids: acetic, formic and levulinic acid
Get PDF"Toxic concentrations of monocarboxylic weak acids present in lignocellulosic hydrolyzates affect cell integrity and fermentative performance of Saccharomyces cerevisiae. In this work, we report the deletion of the general catabolite repressor Mig1p as a strategy to improve the tolerance of S. cerevisiae towards inhibitory concentrations of acetic, formic or levulinic acid. In contrast with the wt yeast, where the growth and ethanol production were ceased in presence of acetic acid 5 g/L or formic acid 1.75 g/L (initial pH not adjusted), the m9 strain (?mig1::kan) produced 4.06?±?0.14 and 3.87?±?0.06 g/L of ethanol, respectively. Also, m9 strain tolerated a higher concentration of 12.5 g/L acetic acid (initial pH adjusted to 4.5) without affecting its fermentative performance. Moreover, m9 strain produced 33% less acetic acid and 50–70% less glycerol in presence of weak acids, and consumed acetate and formate as carbon sources under aerobic conditions. Our results show that the deletion of Mig1p provides a single gene deletion target for improving the acid tolerance of yeast strains significantly.
Microbial recovery of metallic nanoparticles from industrial wastes and their environmental applications
Get PDF"In recent years, metallic nanoparticles (NPs) have been produced by biological methods using bacteria and have been used with remarkable environmental applications. This paper emphasizes the basic aspects of microbial synthesis of metallic nanoparticles, from the selection of the strain to the settings of reaction parameters. Mechanisms involved in the microbial production of NPs are also discussed, summarizing general findings and implications in the process. There is also a section dedicated to the identification of wastes as a source of precious metals and the production of metallic NPs from waste streams containing ionic metals to give a vision of the opportunities to implement microbial synthesis as a treatment–recovery technology. Environmental applications of biogenic NPs are reviewed in detail indicating that the implementation of these nanomaterials enable the achievement of higher removal efficiencies and greater extent of transformation of recalcitrant compounds in wastewater treatment systems. Under this scenario and based on the information reviewed concluding remarks and futures perspectives are enunciated. © 2018 Society of Chemical Industry.
A rapid method for interfacial tension calculation between rock plug and crude oil based on contact angles, application for EOR
Get PDF"Interfacial tension and contact angle are two specific important parameters to take decisions for enhanced oil recovery, for instance, proper chemicals to use for surface tension reduction, expected wettability of solids, interaction between crude oil and rock. For this purpose, the article presents a method for easy calculation of the solid-liquid interfacial tension based on contact angle measurements applying Neumann's correlation and Young's equation. The main idea stands on the calculation of the rock parameters, like wettability, with known substances and extend these results to crude oils. It was possible, based on the results obtained, to establish a relationship between solid-liquid interfacial tension and contact angle for the crude oil – rock system, which can definitively be used for the calculation of interfacial tension of any other fluid spread out on the same kind of rock. A linear regression was obtained with an accuracy as good as R2 = 0.9989. Viscosity as a function of contact angle could also be obtained for the studied crude oils in the same kind of rock.
Phase transition and magnetocaloric properties of Mn50Ni42−xCoxSn8 (0 ≤ x ≤ 10) melt-spun ribbons
Get PDF"The characteristics of magnetostructural coupling play a crucial role in the magnetic field-driven behaviour of magnetofunctional alloys. The availability of magnetostructural coupling over a broad temperature range is of great significance for scientific and technological purposes. This work demonstrates that strong magnetostrucural coupling can be achieved over a wide temperature range (222 to 355?K) in Co-doped high Mn-content Mn50Ni42?xCoxSn8 (0 ? x ? 10) melt-spun ribbons. It is shown that, over a wide composition range with Co content from 3 to 9?at.%, the paramagnetic austenite first transforms into ferromagnetic austenite at T C on cooling, then the ferromagnetic austenite further transforms into a weakly magnetic martensite at T M. Such strong magnetostructural coupling enables the ribbons to exhibit field-induced inverse martensitic transformation behaviour and a large magnetocaloric effect. Under a field change of 5?T, a maximum magnetic entropy change ?S M of 18.6?J?kg?1?K?1 and an effective refrigerant capacity RC eff of up to 178?J?kg?1 can be achieved, which are comparable with or even superior to those of Ni-rich Ni–Mn-based polycrystalline bulk alloys. The combination of high performance and low cost makes Mn–Ni–Co–Sn ribbons of great interest as potential candidates for magnetic refrigeration.
Large reversible magnetic entropy change in rapidly solidified Ni0.895Cr0.105MnGe1.05 melt-spun ribbons
Get PDF"The crystal structure, and magnetic and magnetocaloric properties of rapidly solidified Ni0.895Cr0.105MnGe1.05 melt-spun ribbons is reported. The ribbon samples crystallize into a single-phase hexagonal Ni2In-type structure at room temperature. The as-quenched ribbons showed a second order magnetic transition at 192 ± 1 K at μoH = 5 mT. A magnetic-field-induced transition from an antiferromagnetic (AFM)-like to a ferromagnetic (FM) state of martensite structure was observed in annealed ribbons below the temperature of the martensitic transformation (TM ∼ 245 ± 1 K). The annealed ribbons undergo a first-order magnetostructural transition (MST) with a large maximum reversible magnetic entropy change of ΔSM = 16.1 J kg−1 K−1 (this is about a four-fold increase compared to the ΔSM observed for the bulk sample of the same nominal composition) and RC = 144 J kg−1 for μoΔH = 5 T at temperature T = TM ∼ 245 ± 1 K. The increase in the ΔSM peak value leads to an improved RC compared to that of the bulk sample (122 J kg−1). The observed MCE and quasi-reversible character of ΔSM at the MST illustrates the potential of Ni0.895Cr0.105MnGe1.05 ribbons for magnetic cooling technology.
Genetic mapping identifies loci that influence tomato resistance against Colorado potato beetles
Get PDF"The Colorado potato beetle (CPB; Leptinotarsa decemlineata Say), the most economically important insect pest on potato (Solanum tuberosum L.), also feeds on other Solanaceae, including cultivated tomato (Solanum lycopersicum L.). We used tomato genetic mapping populations to investigate natural variation in CPB resistance. CPB bioassays with 74 tomato lines carrying introgressions of Solanum pennellii in S. lycopersicum cv. M82 identified introgressions from S. pennellii on chromosomes 1 and 6 conferring CPB susceptibility, whereas introgressions on chromosomes 1, 8 and 10 conferred higher resistance. Mapping of CPB resistance using 113 recombinant inbred lines derived from a cross between S. lycopersicum cv UC-204B and Solanum galapagense identified significant quantitative trait loci on chromosomes 6 and 8. In each case, the S. galapagense alleles were associated with lower leaf damage and reduced larval growth. Results of both genetic mapping approaches converged on the same region of chromosome 6, which may have important functions in tomato defense against CPB herbivory. Although genetic mapping identified quantitative trait loci encompassing known genes for tomato acyl sugar and glycoalkaloid biosynthesis, experiments with acyl sugar near-isogenic lines and transgenic GAME9 glycoalkaloid-deficient and overproducing lines showed no significant effect of these otherwise insect-defensive metabolites on CPB performance.
Agave bagasse biorefinery: processing and perspectives
Get PDF"Agave bagasse (AB) is the main solid waste generated by the tequila industry in Mexico, which is an environmental concern due to its considerable volume of production (377,000 Ton in 2016). AB is a lignocellulosic biomass that has been considered as a potential feedstock for different industrial uses in the framework of lignocellulosic biorefinery concept. The lignocellulosic biomass is a complex structure constituted by cellulose, hemicellulose and lignin. Therefore, for a complete waste revalorization, different processing steps would be required. In this work, the scientific advances toward the AB biorefinery composed by three sequential stages: pretreatment, treatment and biofuels production were reviewed. Moreover, the by-products of the process could also be recovered and used for the synthesis of value-added products. This integrative approach of AB in the conceptualized biorefinery generates positive impacts on environment as well as on local and regional economies.
Identification of organic compounds in Cajío Peloid (Cuba)
No full text"Thennal muds ("peloids") are a typical example of natural sediments used in the treatment of different pathologies. Nowadays, because of their use in therapeutics, relax and cosmetic issues, a proper management of peloids is of increasing importance. Peloid characterization and monitoring for quality control purposes are therefore the main aspects of peloid management. Organic chemical quality is directly related with the biological active compounds and the therapeutic properties of peloidsto he used in human health and with the determination suitable contamination.
This study was performed to characterize the organic fraction of Cajio peloid (Cuba) in order to identify the organic components with possible biological effects and establish its natural or anthropogenic origin. For this purpose, a procedure with chromatographic analysis and mass spectrometry detection has been performed.
More than 40 compounds were identified, in Cajio peloid, mainly of natural origin. Among them were found alkanes, steroids, fatty acids, alcohols and other heteroatoms compounds, some of them with reported biological activity in their isolated form as antioxidant, analgesic, anti-inflammatory, and others. The results provide evidence for medical interpretation of the therapeutic action of Cajio peloid in the treatment of inflammatory and dermatological diseases and contribute to the understanding of pelotherapy, giving some scientific basis for its future development.
Temporal and spatial variation of waterbirds at Sayula Lagoon, Jalisco, Mexico: a five-year winter season study
Get PDF"Wetlands in central Mexico are important habitats for assemblages of migratory and resident birds. To study variation in richness and abundance of waterbirds, we conducted monthly observations in 30 permanent plots throughout the Sayula Lagoon, Jalisco, Mexico, during the winter season (from October to March) from 2004-2007 and from 2009-2011. Seventy-three species were recorded; 39 species were winter visitors, and eight species are included in some risk category. The best represented families were: Anatidae, Scolopacidae and Ardeidae. Spatula clypeata and Anser caerulescens were the most abundant species. We found variation in richness between zones (only two were similar), but not between the seasons (only WS4 was different) or months (only NOV was different). Sayula lagoon is a highly dynamic ecosystem influenced by migration and the water inputs occurring during the rainy season.""Los humedales del centro de México son hábitats importantes para ensambles de aves tanto migratorias como residentes. A fin de estudiar la variación en cuanto a riqueza y abundancia de las aves acuáticas, se realizaron observaciones mensuales en 30 parcelas permanentes de toda la laguna de Sayula, Jalisco, México, durante las temporadas invernales (de octubre a marzo) de los años 2004 a 2007 y 2009 a 2011. Se registraron 73 especies. Un total de 39 especies son visitantes invernales y ocho están incluidas en alguna categoría de riesgo. Las familias mejor representadas fueron: Anatidae, Scolopacidae y Ardeidae. Spatula clypeata y Anser caerulescens fueron las especies más abundantes. Se observó variación de la riqueza entre zonas (sólo dos fueron similares), pero no entre estaciones (solo WS4 fue diferente) ni entre meses (solo el mes de noviembre fue diferente). La laguna de Sayula es un ecosistema muy dinámico influido por la migración y el aporte de agua durante la temporada de lluvias.""Els aiguamolls del centre de Mèxic són hàbitats importants tant per a ensambles d’ocells migratoris com residents. Per tal d’estudiar la variació quant a riquesa i abundància dels ocells aquàtics es van portar a terme observacions mensuals en 30 parcel·les permanents de tota la llacuna de Sayula, Jalisco, Mèxic, durant les temporades hivernals (d’octubre a març) dels anys 2004 a 2007 i 2009 a 2011. S’hi van registrar 73 espècies. Un total de 39 espècies són visitants invernals i vuit estan incloses en alguna categoria de risc. Les famílies més ben representades van ser: Anatidae, Scolopacidae i Ardeidae. Spatula clypeata i Anser caerulescens van ser les espècies més abundants. Es va observar una variació de la riquesa entre zones (només dues van ser similars), però no entre estacions (només WS4 va ser diferent) ni entre mesos (només el mes de novembre va ser diferent). La llacuna de Sayula és un ecosistema molt dinàmic influït per la migració i l’aportació d’aigua durant la temporada de pluges.
Self-association of enolase from Trichomonas vaginalis. monomers, dimers, and octamers coexist in solution
Get PDF"We used small-angle X-ray scattering to study the self-association of enolase from Trichomonas vaginalis as a function of the protein concentration and cosolute type. We observed coexisting monomers, dimers, and octamers in variable relative populations, depending on whether Tris–acetate, Tris–HCl, or potassium phosphate buffers were used. Phosphate ions hindered the formation of dimers and octamers. In contrast, the populations of dimers and octamers increased in Tris–acetate or Tris–HCl buffers and additionally increased by augmenting protein concentration or adding magnesium. Single oligomeric species could not be isolated in any of the experimental conditions tested. Furthermore, the secondary and tertiary structures, as well as the temperature-induced denaturation of the mixtures of species, were investigated. The acquired species lost enzymatic activity, but they were prone to interact with plasminogen, as judged from changes in the secondary and tertiary structures upon complex formation.