Main Variables Affecting a Chemical-Enzymatic Method to Obtain Protein and Amino Acids from Resistant Microalgae

he development of microalgae uses requires further investigation in cell disruption alternatives to reduce the costs associated to this processing stage. This study aimed to evaluate the main variables affecting an extraction method to obtain protein and amino acids from microalgae. The method was based on a sequential alkaline-enzymatic process, with separate extractions and noncontrolled pH, and was applied to fresh biomass of a resistant species. The processed microalgae were composed of a consortium with Nannochloropsis sp. as predominant species. After the optimization of the pH of the alkaline reaction, the effect of the time of the alkaline reaction (30-120min), the time (30-120min) and temperature (40-60 degrees C) of the enzymatic reaction, and the biomass concentration (50-150mgml(-1)), on the extraction yields of protein and free amino nitrogen (FAN) and on the final concentration of protein in the extract, was studied using a response surface methodology. Even though all the variables and some interactions among them had a significant effect, the biomass concentration was the most important factor affecting the overall process. The results showed relevant information about the different options in order to maximize not only the response variables individually but also different combinations of them. Assays with optimized values reached maximum yields of 80.3% and 1.07% of protein (% of total protein) and FAN (% of total biomass), respectively, and a protein concentration in the extract of 15.2mgml(-1). The study provided the essential information of an alternative approach to obtain protein and amino acids from fresh biomass of resistant microalgae with a high yield, also opening perspectives for further research in particular aspects

Diagnóstico de malaria en un centro de referencia: Pasado, presente y futuro

La principal estrategia para el control de la malaria, según la Organización Mundial de la Salud (OMS), es un diagnóstico rápido y adecuado seguido de un tratamiento efectivo. Los laboratorios de referencia de microbiología tienen entre sus funciones el desarrollo y validación de nuevas metodologías diagnósticas para ayudar al control y erradicación de la malaria en el mundo y en nuestro caso para evitar la reintroducción en nuestro país. En este trabajo se hace una revisión de los métodos más extendidos para el diagnóstico de malaria: i) métodos clásicos, como son la microscopía y los test de diagnóstico rápido, ii) métodos moleculares, como PCR y LAMP, y, iii) por último, los nuevos avances en microscopía automática e inteligencia artificial.The main strategy for malaria control, according to the World Health Organization (WHO), is a rapid and adequate diagnosis followed by effective treatment. The microbiology reference laboratories have among their functions the development and validation ofnew diagnostic methodologies to help control and eradicate malaria in the world and in our case to avoid its reintroduction in our country. In this work a review of the most widespread methods for malaria diagnosis is made: i) classical methods, such as microscopy and rapid diagnostic tests, ii) molecular methods, such as PCR and LAMP, and, iii) finally, the new advances in automatic microscopy and artificial intelligence

Feedback and Feedforward Control of a Biotrickling Filter for H2S Desulfurization with Nitrite as Electron Acceptor

Biotrickling filters’ control for H2S removal has special challenges because of complexity of the systems. Feedback and feedforward control were implemented in an anoxic biotrickling filter, operated in co-current flow mode and using nitrite as an electron acceptor. The feedback controller was tuned by three methods—two based on Ziegler-Nichols’ rules (step-response and maintained oscillation) and the third using the Approximate M-constrained Integral Gain Optimization (AMIGO). Inlet H2S staircase step perturbations were studied using a feedforward control and the e ect of EBRT considered by feedback control. The tuning method by maintained oscillation shows the lower errors. The selected controller was a PI, because unstable behavior at the lowest H2S inlet loading was found under a PID controller. The PI control was able to maintain an outlet H2S concentration of 14.7 0.45 ppmV at three EBRT, studied at 117 s, 92 s and 67 s. Therefore, desulfurized biogas could be used to feed a fuel cell. Feedforward control enhances BTF performance compared to the system without control. The maximum outlet H2S concentration was reduced by 26.18%, although sulfur selectivity did not exceed 55%, as elemental sulfur was the main oxidation product

Influence of Leachate and Nitrifying Bacteria on Photosynthetic Biogas Upgrading in a Two-Stage System

Photosynthetic biogas upgrading using two-stage systems allows the absorption of carbon dioxide (CO2) in an absorption unit and its subsequent assimilation by microalgae. The production of microalgae requires large amounts of nutrients, thus making scale-up difficult and reducing economic feasibility. The photosynthetic process produces oxygen (O-2) (1 mol per mol of CO2 consumed), which can be desorbed into purified biogas. Two-stage systems reduce its impact but do not eliminate it. In this study, we test the use of landfill leachate as a nutrient source and propose a viable and economical strategy for reducing the O-2 concentration. First, the liquid/gas (L/G) ratio and flow mode of the absorber were optimized for 20% and 40% CO2 with COMBO medium, then landfill leachate was used as a nutrient source. Finally, the system was inoculated with nitrifying bacteria. Leachate was found to be suitable as a nutrient source and to result in a significant improvement in CO2 absorption, with outlet concentrations of 0.01% and 0.6% for 20% and 40% CO2, respectively, being obtained. The use of nitrifying bacteria allowed a reduction in dissolved oxygen (DO) concentration, although it also resulted in a lower pH, thus making CO2 uptake slightly more difficult

Integration of a nitrification bioreactor and an anoxic biotrickling filter for simultaneous ammonium-rich water treatment and biogas desulfurization

A preliminary assessment has been carried out on the integration of an anoxic biotrickling filter and a nitrification bioreactor for the simultaneous treatment of ammonium-rich water and H2S contained in a biogas stream. The nutrient consumption in the biotrickling filter was as follows (mol−1 NO3−-N): 6.3·10−4 ± 1.2·10−4 mol PO43−-P, 0.04 ± 0.05 mol NH4+-N and 0.04 ± 0.03 mol K+-K. Furthermore, it was possible to supply a mixture of biogenic NO3− and NO2− into the biotrickling filter from the nitrification bioreactor to obtain a maximum elimination capacity of 152 gH2S–S m−3 h−1. The equivalence between the two compounds was 1 mol NO3−-N equal to 1.6 mol NO2−-N. The biotrickling filter was also operated under a stepped variable inlet load (30–100 gH2S–S m−3 h−1) and outlet H2S concentrations of less than 150 ppmV were obtained. It was also possible to maintain the outlet H2S concentration close to 15 ppmV with a feedback controller by manipulating the feed flow (in the nitrification bioreactor). Two stepped variable inlet loads were tested (60–111 and 16–102 gH2S–S m−3 h−1) under this type of control. The implementation of feedback control could enable the exploitation of biogas in a fuel cell, since the H2S concentrations were 15.1 ± 4.3 and 15.0 ± 3.4 ppmV. Finally, the anoxic biotrickling filter experienced partial denitrification and this implied a loss of the desulfurization effectiveness related to SO42− production. © 2021 The AuthorsThe Spanish Government ( Ministerio de Economía y Competitividad ) and European FEDER funds provided financial support through the project CTM2012-37927-C03 ‘Monitoring, modelling and control towards the optimization of anoxic and aerobic desulfurizing biotrickling filters’

SENSADO DE ESCARCHA EN EVAPORADORES MEDIANTE CAÍDA DE PRESIÓN (FROST SENSING IN EVAPORATORS THROUGH PRESSURE DROP)

En esta investigación se presentan una serie de pruebas que se realizaron con el objetivo de relacionar la caída de presión del aire que fluye a través del evaporador de un refrigerador, con el volumen de escarcha que se acumula en él. La relación entre la caída de presión y el volumen de escarcha permitió generar un método de sensado que puede ser utilizado para formular un modelo matemático que describa el crecimiento de escarcha en función de la caída de presión. El objetivo de un refrigerador es la conservación de alimentos almacenados en su interior mediante la disminución de la temperatura del aire interno. El inconveniente es la capa de escarcha que se genera sobre el evaporador, puesto que la escarcha genera un aislamiento térmico, disminuyendo la capacidad de transferencia de calor. Medir la cantidad de escarcha formada en el evaporador trae consigo varias posibilidades de mejora para los refrigeradores, la más importante es en el sistema de refrigeración, manteniendo estable la transferencia de calor entre el aire y el evaporador; otra sería en el consumo eléctrico, si se realiza la operación de deshielo con la misma cantidad de escarcha, se puede disminuir el tiempo de deshielo reduciendo el consumo eléctrico, además de que el calor generado por la resistencia también puede disminuir llegando en menor medida a los alimentos.Palabra(s) Clave: deshielo, escarcha, presión, sensado, refrigerador.AbstractIn this research, we presented a series of tests that were conducted with the objective of the pressure drop of the air flowing through the evaporator of a refrigerator, with the volume of frost that accumulates in it. The relationship between pressure drop and clock volume can generate a detection method that can be used to formulate a mathematical model that describes frost growth as a function of pressure drop. The objective of a refrigerator is the preservation of food stored inside by reducing the temperature of the internal air. The drawback is the layer of frost that is generated on the evaporator, since the frost generates a thermal insulation, decreasing the capacity of heat transfer. Measuring the amount of frost formed in the evaporator brings several possibilities of improvement for the refrigerators, the most important is in the refrigeration system, keeping the heat transfer between the air and the evaporator stable; another would be in electricity consumption, if the de-icing operation is carried out with the same amount of frost, the melting time can be reduced by reducing the electricity consumption, besides the heat generated by the resistance can also decrease, reaching a lesser extent to the food.Keywords: De-icing, Frost, Pressure, sensed, Refrigerator

Methane concentration and bacterial communities' dynamics during the anoxic desulfurization of landfill biogas under diverse nitrate sources and hydraulic residence times

Landfill biogas contains certain amounts of H2S that must be removed in order to prevent both equipment corrosion and SO2 emissions to the atmosphere when burnt. Anoxic desulfurization has been proven to be an eco-friendly and cost-efficient method to remove H2S from biogas. Nevertheless, and despite all the reported benefits, the potential consumption of methane (CH4) during the anoxic desulfurization of landfill biogas is a factor that has not yet been thoroughly investigated. The present study evaluates the microbial composition and methane assimilation activity of three microbial samples obtained when feeding different nitrate sources, namely nitrified landfill leachate (M1) or chemical nitrate (M2, M3) with 10 days (M2) and 1.5 days (M3) hydraulic residence times. The samples were characterized by the prevalence of sulfide oxidizing bacteria [Thiomicrospira (11.4-25.5 %), Family Rhodobacteraceae (9.9-14.3 %), Sulfurimonas (0.34-17.9 %), Thioclava (0-23.5 %) and Arcobacter (0-11.5 %)], as well as the presence of methane oxidizing bacteria [Halomonas (0.2-16.0 %), Methylophaga (0-0.2 %) and Methylophilacea (0-0.1 %)] and heterotrophic bacteria [Lentimicrobium (0.1-9.7 %) and Roseovarius (0.1-1.2 %)]. The highest CH4 assimilation levels were reached under anoxic conditions at 34.0 and 50.1 g CH4 m-3 h-1 using nitrate and nitrite, respectively. The oxygen present in the landfill biogas itself had a detrimental effect on the anoxic bioreactor nitrate removal efficiency. The presence of organic matter in the nitrified influent gave rise to CH4 inside the anoxic desulfurization bioreactors, which resulted in the offsetting of the CH4 oxidation caused by methane-oxidizing bacteria (MOB). © 2023 The Authors

Characterization of Bacterial and Archaeal Communities by DGGE and Next Generation Sequencing (NGS) of Nitrification Bioreactors Using Two Different Intermediate Landfill Leachates as Ammonium Substrate

Nitrification-denitrification is an environmentally friendly and cost-effective way to treat landfill leachates. Special attention has been given to the nitrification step, usually the limiting one due to its special sensitivity to environmental factors. Here, the effect of the acclimatization of the nitrifying biomass to two different intermediate landfill leachates with different salt concentrations, COD and BOD5 has been studied. Despite the complete nitrification being successfully performed, the specific nitritation rates were reduced after the biomass adaptation to both landfill leachates caused by the presence of heavy metals and the high salt concentration. NGS analysis of the biomass samples revealed that Proteobacteria (48.5%), Actinobacteriota (14.4%) and Chloroflexi (9.5%) were the dominant phyla in the non-adapted biomass. The leachate feeding led to a decrease in OTU diversity and favored the growth of the phyla Bacteroidetes (27.2%), Euryarchaeota (26.6%) and Proteobacteria (20.0%) accounting for more than 70% of relative abundance. Several OTUs capable of performing the nitritation belong to the Xanthobacteraceae and the Xanthomonadaceae families, the Saccharimonadales order, and the genus Nitrosomonas, Nitrosospira and Paracoccus. In the nitratation process, the Xanthobacteraceae family and Lautropia and Nitrolancea genera were found.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The Spanish Government (Ministry of Economy and Competitiveness) and the Vice-rectorate for Research of the University of Cadiz provided financial support through the project CTM2016-79089-R "Enhancement of landfill gas by an integrated biological system (Biointegra3)" and UCA/REC01VI/2017 (Universidad de Cadiz) respectivel

Acrometástasis en miembro inferior por adenocarcinoma pulmonar

ResumenSe presenta el caso de un paciente que refiere un cuadro de dolor en el miembro inferior izquierdo, más acusado en zona pretibial, atraumático, desde hace 6 meses. El dolor, de características no mecánicas, era refractario al tratamiento, constante, impidiendo el descanso nocturno. Se realizaron estudios complementarios cuyo primer diagnóstico fue osteomielitis, iniciándose tratamiento antibiótico. Al no ceder el cuadro, fue evaluado nuevamente con el diagnostico final de acrometástasis en el miembro inferior izquierdo como primer signo clínico de un adenocarcinoma pulmonar.Acrometástasis en miembro inferior secundaria a un caso de adenocarcinoma pulmonar es infrecuente y suele proceder de cáncer colorrectal y/o tracto urogenital. En ocasiones puede inducir a una sospecha diagnostica errónea, con el consiguiente retraso en el diagnóstico.AbstractThe case is presented of a patient who referred to a clinical history of non-traumatic pain, of six months onset, in the left lower limb, which was more intensive in pretibial region. The pain was non-mechanical in character, treatment resistant, constant, and with night rest difficulty. Several tests were performed, with osteomyelitis being the primary diagnosis, and antibiotics were started. There was no improvement, and the patient was evaluated again, with the final diagnosis of left lower limb acrometastasis as the first clinical sign of lung adenocarcinoma.Acrometastasis in lower limbs due to lung adenocarcinoma is uncommon and usually arises from colorectal or urogenital cancer. Occasionally it may be lead to an erroneous suspicion resulting in a delay in diagnosis

Recent advances in biological technologies for anoxic biogas desulfurization.

Recovery of the energy contained in biogas will be essential in coming years to reduce greenhouse gas emissions and our current dependence on fossil fuels. The elimination of H2S is a priority to avoid equipment corrosion, poisoning of catalytic systems and SO2 emissions in combustion engines. This review describes the advances made in this technology using fixed biomass bioreactors (FBB) and suspended growth bioreactors (SGB) since the first studies in this field in 2008. Anoxic desulfurization has been studied mainly in biotrickling filters (BTF). Elimination capacities (EC) up to 287 gS m-3 h-1 have been achieved, with a removal efficiency (RE) of 99%. Both nitrate and nitrite have been successfully used as electron acceptor. SGBs can solve some operational problems present in FBBs, such as clogging or nutrient distribution issues. However, they present greater difficulties in gas-liquid mass transfer, although ECs of up to 194 gS m-3 h-1 have been reported in both gas-lift and stirred tank reactors. One of the major disadvantages of using anoxic biodesulfurization compared to aerobic biodesulfurization is the need to provide reagents (nitrates and/or nitrites), with the consequent increase in operating costs. A solution proposed in this respect is the use of nitrified effluents, some ammonium-rich effluents nitrified include landfill leachate and digested effluent from the anaerobic digester have been tested successfully. Among the microbial diversity found in the bioreactors, the genera Thiobacillus, Sulfurimonas and Sedimenticola play a key role in anoxic removal of H2S. Finally, a summary of future trends in technology is provided