Toxicidad ejercida por el herbicida atrazina sobre la microalga dulceacuícola "Chlamydomonas reinhardtii" Dangeard

Traballo fin de mestrado (UDC.CIE). Bioloxía molecular, celular e xenética. Curso 2013/201

Biofuels production (ethanol, butanol, hexanol) from renewable sources

Programa Oficial de Doutoramento en Biotecnoloxía Avanzada. 5012V01[Abstract] The search for new energy sources or fuels has increased in recent years. Besides, the increasing demand and greater shortage of conventional fuels, creates the need to replace them by renewable energy sources. Some possible renewable energy sources are (higher) alcohols such as ethanol, butanol, and hexanol. The biological production of ethanol and higher alcohols can be a good and inexpensive way for the obtention of new renewable energy sources. The anaerobic fermentation of waste materials or waste gases is an energy-inexpensive and feedstock-flexible technology for the production of those bioalcohols. The use of those raw materials in biorefineries has two major advantages : it is an efficient method for the elimination of pollutants and compounds with a greenhouse effect (CO, CO2) and it allows to produce solvents with a high commercial value. The main objective of this dissertation is the obtention of higher alcohols using different carbon sources (glucose, carbon monoxide and syngas) with the anaerobic bacterium Clostridium carboxidivorans as biocatalyst. The experimental results are reported in the different chapters of this dissertation, aiming at optimizing the fermentation conditions and operating parameters of the bioconversion of these different carbon sources into ethanol and higher alcohols.[Resumen] La busqueda de nuevas fuentes de energía o combustibles ha incrementado recientemente. Además el incremento de la demanda y de la gran escasez de combustibles convencionales, crea la necesidad de reemplazarlos por fuentes de energía renovables. Algunas de estas posibles fuentes de energía renovables son los alcoholes como etanol, butanol y hexanol La producción biológica de etanol y alcoholes de cadena larga puede ser una buena y barata forma de obtener nuevas fuentes de energía renovable. La fermentación de materiales y gases residuales es una energía barata y una tecnología de materias primas flexibles para la producción de esos bioalcoholes. El uso de esos materiales residuales en biorefinerías t iene dos ventajas principales: es un método eficiente para la eliminación de contaminantes y gases de efecto invernadero (CO, CO2) y permite producir solventes de elevado valor comercial. El principal objetivo de esta tesis es la obtención de alcoholes de cadena larga empleando diferentes fuentes de carbono (glucosa, monóxido de carbono y gas de síntesis) empleando a Clostridium carboxidivorans como biocatalizador. Los resultados están recogidos en los distintos capítulos de esta tesis doctoral, con el objetivo de optimizar las condiciones de fermentación y los parámetros operativos de bioconversión de estas fuentes de carbono en alcoholes.[Resumo] A busqueda de novas fontes de enerxía ou combustibles alternativos incrementou recentemente. Ademais o incremento da demanda e da gran escaseza de combustibles convencionais, crea a necesidade de reemplazarlos por fontes de enerxía renovables. Algunhas destas posibles fontes de enerxía renovables son os alcohois como etanol, butanol e hexanol. A produción biolóxica de etanol e alcohois de cadea longa pode ser unha boa e barata forma de obter novas fontes de enerxía renovables. A fermentación de materiais e gases residuais é unha enerxía barata e unha tecnoloxía de materias primas flexibles para a produción deses bioalcohois. O uso de todos eses materiais residuais en biorefinerías ten dúas vantaxes principais: é un método eficiente para a eliminación de contaminantes e gases de efecto invernadoiro (CO, CO2) e isto permite producir liquides con alto valor comercial. O principal obxectivo desta tese é a obtención de alcohois de cadea longa empregando diferentes fontes de carbono (glucosa, monóxido de carbono e gas de síntese) empregando a Clostridium carboxidivorans como biocatalizador. Os resultados están recollidos nos distintos capítulos desta tese doctoral, co obxectivo de optimizar as condicións de fermentación e os parámetros operativos da bioconversión destas fontes de carbono en al cohois

Effect of salinity on C1-gas fermentation by "Clostridium carboxidivorans" producing acids and alcohols

[Abstract] Clostridium carboxidivorans can produce acids and/or alcohols through syngas fermentation. In that C1-gas fermentation process, the production of acids takes place at higher pH (acetogenesis) (e.g., around 6.00), while the conversion of accumulated acids into alcohols (solventogenesis) is more favourable at a lower pH (e.g., 4.75–5.00). The pH drop, when switching from acetogenesis to solventogenesis, can either be natural—and result from the production of acids—or artificial. In the latter case, for the acidification process, a strong acid (HCl) was added to a syngas fermenting bioreactor in this study, while NaOH was added to increase the pH whenever needed. Cycles of high and low pH were applied in order to switch from acetogenic to solventogenic stages. This pH adjustment procedure leads to the accumulation of salts. The possible inhibitory effect exerted by changes in salinity in the bioreactor was estimated in batch bottles assays, carried out with different salinities (media with different concentrations of sodium chloride) using C. carboxidivorans and CO as a carbon source. At NaCl concentrations below 9 g/L, maximum growth rates around 0.055 h−1 were obtained, whereas increasing the concentration of sodium chloride had a negative effect on bacterial growth and CO consumption. In the case of the most concentrated bottles, above 15 g/L NaCl no relevant growth was observed. Also, the IC50, i.e. concentration yielding 50% growth inhibition, was estimated, and reached a value of 11 g/L sodium chloride.Ministerio de Economía, Industria y Competitividad; CTQ2017-88292-

Atrazine induced changes in elemental and biochemical composition and nitrate reductase activity in Chlamydomonas reinhardtii

Herbicides play an important role in agricultural practices but the introduction of these compounds into the aquatic environment can have severe consequences for non-target organisms such as microalgae. The ubiquitous green freshwater microalga Chlamydomonas reinhardtii, a model species in all aspects of microalgal physiology, was used to assess the toxicity of atrazine, one of the most widely used herbicides throughout the world. Atrazine acts on photosynthesis and therefore can affect non-target primary producers, such as microalgae. Growth, dry weight, elemental composition, photosynthetic pigments and protein contents and nitrate reductase activity were studied. After 96 h of exposure to different atrazine concentrations all the parameters studied were affected, but different sensitivities to the herbicide were shown. Nitrate reductase (NR) activity was strongly affected even at an atrazine concentration that did not affect growth (0.1 μM); the lowest concentrations of atrazine assayed (0.1 and 0.25 μM) provoked a > 40% decrease in NR activity and NR decreased > 80% with atrazine concentrations of 0.5 μM. C/N ratio was also affected by all the atrazine concentrations assayed. Nitrate reductase activity and C/N ratio were better indicators of the cellular stress state than data on other biochemical components or growth rate. Among cell parameters assayed, the NR activity stood out as a sensitive cytotoxicity endpoint and the activity of this enzyme can be suggested as a sensitive biomarker of stress induced by atrazine in C. reinhardtii.Ministerio de Economia y Competitividad; CGL2010-15993/BO

Does perceived corruption influence the credit insurance market in Spain? An analysis using the Google Trends tool

[ES] En este estudio, se realiza un análisis del efecto de la corrupción percibida en la actividad del mercado de seguros de crédito o CDSs en España en el periodo comprendido entre los años 2008 y 2018. Para medir la corrupción percibida se utiliza la herramienta Google Trends para la palabra “corrupcion”. Por su parte, para medir la actividad del mercado de CDSs, se utiliza la evolución de los Credit Default Swaps o CDSs a 5 años. Posteriormente, se realiza un análisis empírico a través de la metodología de regresión y el análisis out-of-sample para comprobar la capacidad predictiva del modelo. Los resultados muestran que la corrupción percibida es influyente en la evolución de los CDSs y que su influencia es mayor en los años en los que la economía del país no atraviesa una crisis.[EN] In this paper, we perform an analysis about the effect of the perception of corruption in the activity of the credit insurance or CDS market in Spain during the period between 2008 and 2018. To measure the perception of corruption, we use Google Trends tool for the keyword “corrupcion”. On the other hand, to proxy the activity of the CDS market, we use the evolution of the 5-year CDSs. Subsequently, an empirical analysis is carried out through regression methodology and out-of-sample analysis to verify the predictive capacity of the model. The results show that perceived corruption impacts the evolution of CDSs, and its influence is greater in the years in which the country's economy does not face a crisis.S

Factors Affecting the Optimisation and Scale-up of Lipid Accumulation in Oleaginous Yeasts for Sustainable Biofuels Production

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The recent unprecedented increase in energy demand has led to a growing interest in emerging alternatives such as the production of microbial lipids with high energy density and environmentally-friendly characteristics. Oleaginous yeasts represent a versatile and attractive tool for the accumulation of such lipids, also known as single cell oils (SCOs), used to manufacture biofuels (e.g., biodiesel, aviation fuel) and bioproducts. This review provides an overview of the most common oleaginous species, analysing the viability of typical feedstocks and their effect on lipid accumulation. The best results in terms of lipid content using glucose, glycerol, lignocellulose, or acetic acid as substrates are 81.4, 70, 68.2 and 73.4% (w/w), respectively. Besides, an analysis of the parameters that can affect lipid production is also presented. For instance, the optimum conditions for lipid accumulation are usually a C/N ratio between 100 and 200, pH between 5 and 6 (being more alkaline if acids are used as substrates) and temperature around 30 °C. Besides, genetic modifications generally allow to increase the lipid yield, even by up to 400%. Finally, some cost analysis is provided for scaling-up, with feedstock costs estimated at 50–80%, followed by fermenter costs, and downstream costs estimated at around 13%.This study was funded by the Spanish Ministry of Science and Innovation and European FEDER funds (PID2020-117805RB-I00). The manuscript is based on research related to COST action Yeast4Bio. RR thanks the Ministry of Science and Innovation for financial support of his doctoral research (E-15-2019-0344365). CFB (ED481A-2020/028) thanks Xunta de Galicia for financing her doctoral research. The authors, belonging to the BIOENGIN group, thank Xunta de Galicia for financial support to Competitive Reference Research Groups (ED431C 2021/55)Xunta de Galicia; ED481A-2020/028Xunta de Galicia; ED431C 2021/5

The impact of hearing loss on language performance in older adults with different stages of cognitive function

[Abstract] Purpose. The possible relationship between audiometric hearing thresholds and cognitive performance on language tests was analyzed in a cross-sectional cohort of older adults aged ≥65 years (N=98) with different degrees of cognitive impairment. Materials and methods. Participants were distributed into two groups according to Reisberg’s Global Deterioration Scale (GDS): a normal/predementia group (GDS scores 1–3) and a moderate/moderately severe dementia group (GDS scores 4 and 5). Hearing loss (pure-tone audiometry) and receptive and production-based language function (Verbal Fluency Test, Boston Naming Test, and Token Test) were assessed. Results. Results showed that the dementia group achieved significantly lower scores than the predementia group in all language tests. A moderate negative correlation between hearing loss and verbal comprehension (r=−0.298; P<0.003) was observed in the predementia group (r=−0.363; P<0.007). However, no significant relationship between hearing loss and verbal fluency and naming scores was observed, regardless of cognitive impairment. Conclusion. In the predementia group, reduced hearing level partially explains comprehension performance but not language production. In the dementia group, hearing loss cannot be considered as an explanatory factor of poor receptive and production-based language performance. These results are suggestive of cognitive rather than simply auditory problems to explain the language impairment in the elderly

Verbal fluency, naming and verbal comprehension: three aspects of language as predictors of cognitive impairment

[Abstract] Objectives: To establish the possible relationship among three components of language (verbal fluency, naming and comprehension) and cognitive impairment as well as to determine the usefulness of language assessment tests to predict or monitor the development of cognitive impairment. Method: A comparative, descriptive and cross-sectional study was performed on 82 subjects 65 years of age who were cognitively assessed with the Mini Mental State Examination and were divided into two groups: Group A comprised of subjects classified as levels 1, 2 and 3 on the Reisberg’s Global Deterioration Scale (GDS) and group B comprised of subjects at levels 4 and 5 of the GDS. Language skills were assessed by the Verbal Fluency Test, Boston Naming Test and Token Test. Results: An inverse relationship between performance on language tests and cognitive impairment level was observed with a more pronounced effect observed on fluency and comprehension tests. Conclusion: Language assessments, especially fluency and comprehension, were good indicators of cognitive impairment. The use of these assessments as predictors of the degree of cognitive impairment is discussed in-depth

Four Decades of COPD Mortality Trends: Analysis of Trends and Multiple Causes of Death

There is little information on chronic obstructive pulmonary disease (COPD) mortality trends, age of death, or male:female ratio. This study therefore sought to analyze time trends in mortality with COPD recorded as the underlying cause of death from 1980 through 2017, and with COPD recorded other than as the underlying cause of death. We conducted an analysis of COPD deaths in Galicia (Spain) from 1980 through 2017, including those in which COPD was recorded other than as the underlying cause of death from 2015 through 2017. We calculated the crude and standardized rates, and analyzed mortality trends using joinpoint regression models. There were 43,234 COPD deaths, with a male:female ratio of 2.4. Median age of death was 82 years. A change point in the mortality trend was detected in 1996 with a significant decrease across the sexes, reflected by an annual percentage change of −3.8%. Taking deaths into account in which COPD participated or contributed without being the underlying cause led to an overall 42% increase in the mortality burden. The most frequent causes of death when COPD was not considered to be the underlying cause were bronchopulmonary neoplasms and cardiovascular diseases. COPD mortality has decreased steadily across the sexes in Galicia since 1996, and age of death has also gradually increased. Multiple-cause death analysis may help prevent the underestimation of COPD mortalityS

Breaking of internal waves and turbulent dissipation in an anticyclonic mode Water Eddy

A four-month glider mission was analyzed to assess turbulent dissipation in an anticyclonic eddy at the western boundary of the subtropical North Atlantic. The eddy (radius ≈ 60 km) had a core of low potential vorticity between 100–450 m, with maximum radial velocities of 0.5 m s−1 and Rossby number ≈ −0.1. Turbulent dissipation was inferred from vertical water velocities derived from the glider flight model. Dissipation was suppressed in the eddy core (ε ≈ 5×10−10 W kg−1) and enhanced below it (> 10−9 W kg−1). Elevated dissipation was coincident with quasi-periodic structures in the vertical velocity and pressure perturbations, suggesting internal waves as the drivers of dissipation. A heuristic ray-tracing approximation was used to investigate the wave-eddy interactions leading to turbulent dissipation. Ray-tracing simulations were consistent with two types of wave-eddy interactions that may induce dissipation: the trapping of near-inertial wave energy by the eddy’s relative vorticity, or the entry of an internal tide (generated at the nearby continental slope) to a critical layer in the eddy shear. The latter scenario suggests that the intense mesoscale field characterizing the western boundaries of ocean basins might act as a ‘leaky wall’ controlling the propagation of internal tides into the basins’ interior