Producción de polihidroxialcanoatos a partir de agua residual de la industria cervecera

[Resumo] Hoxe en día os plásticos convertéronse en algo especial na nosa vida diaria. A versatilidade destes materiais convertelos en materias aptos para un gran rango de aplicacións, desde o campo da medicina hasta o seu emprego na industria do automóbil ou como envases contedores. O feito de que sexan materiais sintéticos permite a manipulación da súa estrutura química, podendo adoptar diferentes formas (desde fibras ate películas finas). Estes a súa vez presentan diferentes graos de resistencia física e unha elevada resistencia química. Sen embargo, ao non ser biodegradábeis, a acumulación dos plásticos no medio ambiente estase a converter nun problema medioambiental de gran dimensión. Actualmente as formas de eliminación dos plásticos do medio ambiente mais frecuentes son a incineración e o reciclaxe, pero estas presentan varios problemas. A incineración de materiais plásticos pode levar á emisión de sustancias tóxicas ó medio ambiente como poden ser os ácido clorhídrico e o ácido cianhídrico. En canto a reciclaxe, esta está restrinxida a só algúns dos materiais plásticos e, ademais, con cada ciclo de reciclaxe prodúcense cambios nos materias plásticos o que condiciona o seu uso en aplicacións posteriores. A alternativa a este problema sería o emprego de plásticos biodegradábeis que presenten propiedades similares ós dos plásticos convencionais. Entre os plásticos biodegradábeis que se coñecen na actualidade, os máis prometedores son os polihidroxialcanoatos (PHA). Estes son completamente biodegradábeis, xa que son producidos polos microorganismos como material de reserva cando son sometidos a condicións desfavorábeis para o crecemento celular na presenza dun exceso de carbono. Por outro lado, as súas propiedades son moi similares as do polipropileno e o polietileno. Na actualidade xa existen varias empresas que producen este tipo de polímeros a escala industrial, sen embargo, a substitución dos plásticos convencionais por estes polímeros non é factible hoxe en día, debido ós maiores costes de estes materiais no mercado. O alto prezo destes materiais debese en gran parte ós costes dos substratos empregados na súa produción. A produción destes compostos ten lugar mediante o emprego de cultivos puros, o que fai necesario o uso de substratos puros (glucosa, sacarosa, alcohois, etc.) e condicións estériles. Unha alternativa para Resumen y objetivos 4 reducir o prezo de mercado destes produtos sería o emprego de cultivos puros e o uso de residuos coma substratos. A produción de PHA a partir de cultivos mixtos ten lugar en sistemas nos que o doador e o aceptor de electróns están fisicamente separados (sistemas anaerobio/aerobio ou anóxico/aerobio) ou ben en sistemas onde se favorece un crecemento desequilibrado mediante a imposición de condicións da alimentación dinámica (o substrato non está dispoñíbel). No presente traballo xurdiu a posibilidade de producir PHA empregando un cultivo mixto sometido a condicións aerobias de alimentación dinámica e un efluente residual da industria cervexeira como substrato. O auga residual da industria cervexeira caracterizouse por un alto contido de materia orgánica facilmente biodegradábel que baixo condicións de fermentación acidoxénica pode ser transformada na súa totalidade en ácidos graxos volátiles (AGV), principais precursores dos PHA nos procesos aerobios de alimentación dinámica de substrato. O proceso empregado para o desenvolvemento deste traballo constou de tres etapas: 1. Fermentación acidoxénica: necesaria para transformar a materia orgánica presente na auga residual en AGV. 2. Selección do cultivo aerobio: etapa aerobia na que se selecciona un cultivo con capacidade de acumular PHA mediante o sometemento da biomasa a condicións alternas de presenza e ausencia de substrato. 3. Produción do PHA: o cultivo mixto seleccionado na segunda etapa é sometido a un pulso de substrato contendo altas concentracións de AGV para desta maneira promover ó almacenamento do PHA no interior das bacterias.[Abstract] Nowadays plastics are considered essential in our daily life. The versatility of these materials makes their application feasible in a great range of different industrial sectors, from medicine to their use in the car industry or as a container. As they are synthetic materials, their chemical structure can be manipulated being capable of presenting different shapes (from fibres to thin films). These materials also present different grades of physical resistance and a high chemical resistance. However, since they are not biodegradable, they accumulate in the environment causing a waste disposal problem. Until now, solutions to plastic waste management include incineration or recycling. However, most of these techniques present some problems. The incineration of plastic materials can lead to the release of toxic substances to the environment like chloridric acid and hydrogen cyanide. Moreover, recycling is restricted to some plastic materials and, in each cycle of recycling, the plastic materials suffer some changes conditioning their use in further applications. The alternative to this problem would be to use biodegradable plastics that present similar properties to the conventional ones. Nowadays, PHA are among the most promising bioplastics. PHA are completely biodegradable, as they are produced by microorganisms as reserve material when bacteria are submitted to unbalanced growth conditions in presence of high carbon concentrations. On the other hand, their properties are similar to those presented by polypropylene and polyethylene. Although PHA are already produced at industrial scale, their applications are limited and they are not yet considered as commodity materials since their production costs are still much higher than those of synthetic polymers. Until now, the main obstacle to replace conventional plastics by PHA is the great difference in cost. PHA price is highly dependent on substrate costs. An alternative to reduce PHA prices would be to use mixed cultures and cheap substrates such as waste. PHA storage by mixed cultures occurs in systems where electron donor and acceptor availability are separated (anaerobic/aerobic systems or anoxic/aerobic systems) or when the substrate is not continuously available to the microorganisms (aerobic dynamic feeding). In this work, it was proposed to produce PHA using a mixed culture submitted to aerobic conditions of dynamic feeding and using an industrial effluent from s brewery industry as substrate. Brewery wastewater is characterized by a high organic matter content easily biodegradable which, under acidogenic fermentation conditions, can be totally transformed into volatile fatty acids (VFA), the main precursors used to produce PHA under aerobic dynamic conditions. The process used to develop this work consisted on three steps: 1. Acidogenic fermentation: needed to transform organic matter present in wastewater into VFA. 2. Aerobic culture selection step: aerobic step in which a culture with PHA storage ability is selected by submitting the biomass to transient conditions of substrate presence and absence. 3. PHA production step: the mixed culture selected in the second step is submitted to a substrate pulse containing high VFA concentration to promote the PHA storage inside the cell.[Resumen] Hoy en día los plásticos se han convertido en algo esencial en nuestra vida cotidiana. La versatilidad de estos materiales los convierte en materiales aptos para un gran rango de aplicaciones, desde el campo de la medicina hasta su empleo en la industria del automóvil o como envases contenedores. El hecho de que sean materiales sintéticos permite la manipulación de su estructura química, pudiendo adoptar diferentes formas (desde fibras a películas finas). Estos a su vez presentan diferentes grados de resistencia física y una elevada resistencia química. Sin embargo al no ser biodegradables, la acumulación de los plásticos en el medio ambiente se está convirtiendo en un problema medioambiental de gran dimensión. Actualmente las formas de eliminación de los plásticos del medioambiente más frecuentes son la incineración y el reciclaje, pero estas presentan varios problemas. La incineración de materiales plásticos puede llevar a la emisión de sustancias tóxicas al medio ambiente como pueden ser ácido clorhídrico o cianhídrico. En cuanto al reciclaje, este está restringido a solo algunos de los materiales plásticos y, además, con cada ciclo de reciclado se producen cambios en los materiales plásticos lo que condiciona su uso en posteriores aplicaciones. La alternativa a este problema sería el empleo de plásticos biodegradables que presenten propiedades similares a la de los plásticos convencionales. Entre los plásticos biodegradables que se conocen en la actualidad, los más prometedores son los polihidroxialcanoatos (PHA). Estos son completamente biodegradables, ya que son producidos por los microorganismos como material de reserva cuando son sometidos a condiciones desfavorables para el crecimiento en presencia de un exceso de carbono. Por otro lado, sus propiedades son muy similares a las del polipropileno y a las del polietileno. Actualmente ya existen varias empresas que producen este tipo de polímeros a escala industrial, sin embargo, la sustitución de los plásticos convencionales por estos polímeros no es factible a día de hoy, debido a los mayores costes de estos materiales en el mercado. El alto precio de estos materiales se debe en gran parte a los costes de los sustratos empleados en la producción. La producción de estos compuestos tiene lugar mediante el empleo de cultivos puros, lo que hace necesario el uso de sustratos puros (glucosa, sacarosa, alcoholes, etc) y condiciones estériles. Una alternativa para reducir el precio de mercado de estos productos sería mediante el empleo de cultivos mixtos y el uso de residuos como sustratos. La producción de PHAs a partir de cultivos mixtos tiene lugar en sistemas en los que el donador y el aceptor de electrones están físicamente separados (sistemas anaerobio/aerobio o anóxico/aerobio) o bien en sistemas donde se favorece un crecimiento desequilibrado mediante la imposición de condiciones de alimentación dinámica (el sustrato no está siempre disponible). En el presente trabajo se planteó la posibilidad de producir PHA empleando un cultivo mixto sometido a condiciones aerobias de alimentación dinámica y un efluente residual de la industria cervecera como sustrato. El agua residual de la industria cervecera se caracteriza por un alto contenido de materia orgánica fácilmente biodegradable que bajo condiciones de fermentación acidogénica puede ser transformada prácticamente en su totalidad en ácidos grasos volátiles (AGV), principales precursores de los PHA en los procesos aerobios de alimentación dinámica de sustrato. El proceso empleado para el desarrollo de este trabajo constó de tres etapas: 1. Fermentación acidogénica: necesaria para transformar la materia orgánica presente en el agua residual en AGV. 2. Selección del cultivo aerobio: Etapa aerobia en la que se selecciona un cultivo con capacidad de acumular PHA mediante el sometimiento de la biomasa a condiciones alternas de presencia y ausencia de sustrato. 3. Producción de PHA: el cultivo mixto seleccionado en la segunda etapa se somete a un pulso de sustrato conteniendo altas concentraciones de AGV para de esta manera promover el almacenamiento de PHA en el interior de las bacterias

Procedimientos robustos para el análisis de la varianza en un diseño en bloques aleatorizados completos

En los diseños en bloques aleatorizados generalmente seemplean estimadores de cuadrados minimos, que no son robustos. Si se consideran I tratamientos, J bloques y una observacionpor casilla y se supone el modelo lineal Xij = αi + βj + uij,con uij variables aleatorias i.i.d., es natural aplicar elmétodo de M-estimadores propuesto por Huber para el modelolineal general a este caso particular con el propósito deobtener estimadores robustos. Sin embargo en este caso no secumplen las hipótesis que aseguran la consistencia y normalidadasintótica de M-estimadores para modelos lineales (Huber (1973), Yohai y Maronna (1979), Portnoy (1984 y 1985)). Eneste trabajo se demuestran la consistencia y normalidadasintótica de los M-estimadores de los parámetros αi, secompara su eficiencia asintótica con la de los estimadores decuadrados mínimos, se estudia su punto de ruptura, se proponeun test basado en estos M-estimadores y se compara porsimulación la eficiencia de este test con el test del análisisde la varianza clásico y con dos tests de rangos.Fil: García Ben, Marta Susana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Robust estimation for the multivariate linear model based on a τ-scale

AbstractWe introduce a class of robust estimates for multivariate linear models. The regression coefficients and the covariance matrix of the errors are estimated simultaneously by minimizing the determinant of the covariance matrix estimate, subject to a constraint on a robust scale of the Mahalanobis norms of the residuals. By choosing a τ-estimate as a robust scale, the resulting estimates combine good robustness properties and asymptotic efficiency under Gaussian errors. These estimates are asymptotically normal and in the case where the errors have an elliptical distribution, their asymptotic covariance matrix differs only by a scalar factor from the one corresponding to the maximum likelihood estimate. We derive the influence curve and prove that the breakdown point is close to 0.5. A Monte Carlo study shows that our estimates compare favorably with respect to S-estimates

Valuable product production from wood mill effluents

Fibreboard production is one of the most important industrial activities in Galicia (Spain). Great amounts of wastewater are generated, with properties depending on the type of wood, treatment process, final product and water reusing, among others. These effluents are characterized by a high chemical oxygen demand (COD), low pH and nutrients limitation. Aerobic and anaerobic processes have been used for their treatment. Presently, bioplastics production (mainly polyhydroxyalkanoates or PHA) from wastewaters with mixed cultures is being studied. Substrate requirements for these processes are a high organic matter content and low nutrient concentration. Therefore, wood mill effluents could be a suitable feedstock. PHA production from wastewaters is carried out in three steps. First, complex organic matter is converted into volatile fatty acids (VFA) through acidogenic fermentation. Then, VFA are used as substrate in an aerobic sequencing batch reactor (SBR), in which the enrichement of PHA producing bacteria from a mixed culture is favoured. Finally, the sludge from the SBR is fed with a pulse containing high VFA concentrations, resulting in PHA accumulation inside the cells. In this work, the possibility of applying this process to wood mill effluents is proposed. An acidification percentage of 37% and a storage yield (YSTO) of 0.23 Cmmol/Cmmol were obtained

Partial Nitrification of Wastewater from an Aminoplastic Resin Producing Factory

Nitrification via nitrite was studied in two aerobic reactors treating wastewater from an aminoplastic resin producing factory at HRT varying between 1.37-1.89 and 2.45-3.63 days. Both reactors were fed with concentrations of 366, 450, 1099 and 1899 mg N-NH4+/L. In general in the reactor operated at a lower HRT, the nitritation percentage decreased from 87.2 to 21.6%, while the nitratation percentage remained always lower than 2.5% (except in the last period) when the ammonium concentration was increased. This behaviour could be due to the inhibition of the ammonium and nitrite oxidation produced by high free ammonia concentrations up to 179.3 mg N-NH3/L. In the reactor operated at a higher HRT, the nitritation percentage decreased and the nitratation percentage increased from 88.6 to 39.6% and from 0.65 to 35.7%, respectively, due to an increase of the dissolved oxygen concentration from 0.76 to 1.02 mg O2/L. However, when ammonium was fed at a concentration of 1898.7 mg N-NH4+/L, the nitritation increased and the nitratation decreased, probably as a result of the accumulation of free ammonia up to 2.04 mg N-NH3/L, meaning that nitrite oxidizers were inhibited. Nitrite build-up was observed after each modification of ammonium concentration in the feed

Bioplastic production using wood mill effluents as feedstock

[Abstract] Fibreboard production is one of the most important industrial activities in Galicia (Spain). Great amounts of wastewater are generated, with properties depending on the type of wood, treatment process, final product and water reusing, among others. These effluents are characterized by a high chemical oxygen demand, low pH and nutrients limitation. Although anaerobic digestion is one of the most suitable processes for the treatment, lately bioplastics production (mainly polyhydroxyalkanoates) from wastewaters with mixed cultures is being evaluated. Substrate requirements for these processes consist of high organic matter content and low nutrient concentration. Therefore, wood mill effluents could be a suitable feedstock. In this work, the possibility of producing bioplastics from to wood mill effluents is evaluated. First, wood mill effluent was converted to volatile fatty acids in an acidogenic reactor operated at two different hydraulic retention times of 1 and 1.5 d. The acidification percentage obtained was 37% and 42%, respectively. Then, aerobic batch assays were performed using fermented wood mill effluents obtained at different hydraulic retention times. Assays were developed using different cultures as inoculums. The maximum storage yield of 0.57 Cmmol/Cmmol was obtained when when the culture was enriched on a synthetic media

Development of polymorphic microsatellite markers for the Killarney Fern (Vandenboschia speciosa, Hymenophyllaceae)

Premise of the study: We characterize 10 microsatellite loci in the endangered fern Vandenboschia speciosa (Hymenophyllaceae), enabling studies on the genetic population structure of this Macaronesian-European species using DNA hypervariable markers. Methods and Results: Ten primer sets were developed and tested on 47 individuals in a total of two Iberian populations of V. speciosa. The primers amplified di- and hexanucelotide repeats. The number of alleles ranged from two to eight, and the expected heterozygosity ranged from 0.107 to 0.807 among the populations analyzed. Conclusions: The 10 microsatellite markers developed will be useful in characterizing the genetic diversity of V. speciosa and understanding its population structure (including the possible structure between sporophyte and gametophyte phases) and biogeographic history, and will provide important genetic data for the conservation of this species.This study was supported by the Regional Andalusian Government (project P10-RNM-6198). C.G.L. was funded by a postdoctoral grant from the Regional Andalusian Government. S.B.S. and L.T.C. were funded by a Beca-Iniciación a la Investigación grant from the Universidad de Granada during 2012–2013 and 2014–2015, respectively. I.M.A. was funded by a Beca-Colaboración grant (Spanish Government)

Enhancing Bioproducts in Seaweeds via Sustainable Aquaculture: Antioxidant and Sun-Protection Compounds

Marine macroalgae are considered an untapped source of healthy natural metabolites and their market demand is rapidly increasing. Intertidal macroalgae present chemical defense mechanisms that enable them to thrive under changing environmental conditions. These intracellular chemicals include compounds that can be used for human benefit. The aim of this study was to test cultivation protocols that direct seaweed metabolic responses to enhance the production of target antioxidant and photoprotective biomaterials. We present an original integrated multi-trophic aquaculture (IMTA) design, based on a two-phase cultivation plan, in which three seaweed species were initially fed by fish effluents, and subsequently exposed to various abiotic stresses, namely, high irradiance, nutrient starvation, and high salinity. The combined effect of the IMTA’s high nutrient concentrations and/or followed by the abiotic stressors enhanced the seaweeds’ content of mycosporine-like amino acids (MAAs) by 2.3-fold, phenolic compounds by 1.4-fold, and their antioxidant capacity by 1.8-fold. The Sun Protection Factor (SPF) rose by 2.7-fold, and the chlorophyll and phycobiliprotein synthesis was stimulated dramatically by an order of magnitude. Our integrated cultivation system design offers a sustainable approach, with the potential to be adopted by emerging industries for food and health applicationsPartial funding for open access charge: Universidad de Málag

Evaluating the impacts of tiered restrictions introduced in England in December 2020 on covid-19 hospitalisations: a synthetic control study

ABSTRACTObjectivesTo assess the impact of Tier 3 covid-19 restrictions implemented in December 2020 in England on covid-19 hospital admissions compared to Tier 2 restrictions, and its potential variations by neighbourhood deprivation levels and the prevalence of the Alpha variant (B.1.1.7).DesignObservational study utilising a synthetic control approach. Comparison of changes in weekly hospitalisation rates in Tier 3 areas to a synthetic control group derived from Tier 2 areas.SettingEngland between 4thOctober 2020 and 21stFebruary 2021.Participants23 million people under Tier 3 restrictions, compared to a synthetic control group derived from 29 million people under Tier 2 restrictions.InterventionsImplementation of Tier 3 covid-19 restrictions in designated areas on 7thDecember 2020, with additional constraints on indoor and outdoor meetings and the hospitality sector compared to less stringent Tier 2 restrictions.Main Outcome MeasuresWeekly covid-19 related hospital admissions for neighbourhoods in England over a 12-week period following the interventions.ResultsThe introduction of Tier 3 restrictions was associated with a 17% average reduction in hospital admissions compared to Tier 2 areas (95% CI 13% to 21%; 8158 (6286 to 9981) in total)). The effects were similar across different levels of neighbourhood deprivation and prevalence of the Alpha variant (B.1.1.7).ConclusionsRegionally targeted Tier 3 restrictions in England had a moderate but significant effect on reducing hospitalisations. The impact did not exacerbate socioeconomic inequalities during the pandemic. Our findings suggest that regionally targeted restrictions can be effective in managing infectious diseases.SUMMARY BOXESWhat is already known on this topic— Previous studies of localised non-pharmaceutical interventions (NPIs) found that they could be effective in reducing covid-19 transmissions.— covid-19 hospitalisation was a key indicator of healthcare resource dynamics, encompassing supply, demand, burden, and allocation, during the pandemic.— There is a need for a detailed examination of the impact of specific localised restrictions in the UK, such as Tier 3 measures, on hospital admissions to inform targeted public health strategies.What this study adds— This study found that additional localised restrictions on outdoor gatherings and in the hospitality sector were effective in mitigating hospital admissions during the pandemic.How this study might affect research, practice or policy— This study provides evidence for future public health policies and preparedness strategies supporting the use of differential regional restrictions during pandemics.</jats:sec