Lithic cyanobacterial communities in the polyextreme Sahara Desert: implications for the search for the limits of life.

The hyperarid Sahara Desert presents extreme and persistent dry conditions with a limited number of hours during which the moisture availability, temperature and light allow phototrophic growth. Some cyanobacteria can live in these hostile conditions by seeking refuge under (hypolithic) or inside (endolithic) rocks, by colonizing porous spaces (cryptoendoliths) or fissures in stones (chasmoendoliths). Chroococcidiopsis spp. have been reported as the dominant or even the only phototrophs in these hot desert lithic communities. However, the results of this study reveal the high diversity of and variability in cyanobacteria among the sampled habitats in the Sahara Desert. The chasmoendolithic samples presented high coccoid cyanobacteria abundances, although the dominant cyanobacteria were distinct among different locations. A high predominance of a newly described cyanobacterium, Pseudoacaryochloris sahariense, was found in hard, compact, and more opaque stones with cryptoendolithic colonization. On the other hand, the hypolithic samples were dominated by filamentous, non-heterocystous cyanobacteria. Thermophysiological bioassays confirmed desiccation and extreme temperature tolerance as drivers in the cyanobacterial community composition of these lithic niches. The results of the present study provide key factors for understanding life strategies under polyextreme environmental conditions. The isolated strains, especially the newly described cyanobacterium P. sahariense, might represent suitable microorganisms in astrobiology studies aimed at investigating the limits of life.

Monitoring COVID-19 through SARS-CoV-2 quantification in wastewater: progress, challenges and prospects.

Wastewater-Based Epidemiology (WBE) is widely used to monitor the progression of the current SARS-CoV-2 pandemic at local levels. In this review, we address the different approaches to the steps needed for this surveillance: sampling wastewaters (WWs), concentrating the virus from the samples and quantifying them by qPCR, focusing on the main limitations of the methodologies used. Factors that can influence SARS-CoV-2 monitoring in WWs include: (i) physical parameters as temperature that can hamper the detection in warm seasons and tropical regions, (ii) sampling methodologies and timetables, being composite samples and Moore swabs the less variable and more sensitive approaches, (iii) virus concentration methodologies that need to be feasible and practicable in simpler laboratories and (iv) detection methodologies that should tend to use faster and cost-effective procedures. The efficiency of WW treatments and the use of WWs for SARS-CoV-2 variants detection are also addressed. Furthermore, we discuss the need for the development of common standardized protocols, although these must be versatile enough to comprise variations among target communities. WBE screening of risk populations will allow for the prediction of future outbreaks, thus alerting authorities to implement early action measurements.

Simple and Sustainable Preparation of Cathodes for Li-S Batteries: Regeneration of Granular Activated Carbon from the Odor Control System of a Wastewater Treatment Plant.

To obtain a wide variety of green materials, numerous investigations have been undertaken on industrial waste that can act as sustainable resources. The use of hazardous wastes derived from wastewater treatment plants (WWTPs), especially the activated carbon used in odor control systems, is a highly abundant, scalable, and cost-effective strategy. The reuse of waste materials is a key aspect, especially for the sustainable development of emerging energy storage systems, such as lithium-sulfur (Li-S) batteries. Herein, granular active carbons from two WWTP treatment lines were regenerated in air at low temperature and utilized as the sulfur host with micro-/mesoporous framework. The resulting regenerated carbon and sulfur composites were employed as cathodes for Li-S cells. The SL-ACt3@S composite electrode with 60 wt% loaded sulfur exhibited a remarkable initial capacity of 1100 mAh g-1 at C/10 rate and higher than 800 mAh g-1 at C/2. Even at a rate of 1C, it maintained a high capacity of almost 700 mAh g-1 with a capacity retention of 85.4 % after 350 cycles, demonstrating a very low capacity fading of only 0.042 % per cycle. It is essential to note that the coulombic efficiency was always higher than 96 % during all the cycles. In this proposal, the only used source material was expired carbon from WWTP that was obtained with a simple and effective regeneration process. This "trash into treasure" strategy leads to a new way for using hazardous waste material as high-performance and environmentally safe electrodes for advanced Li-S batteries.

Microenvironmental Conditions Drive the Differential Cyanobacterial Community Composition of Biocrusts from the Sahara Desert.

The Sahara Desert is characterized by extreme environmental conditions, which are a unique challenge for life. Cyanobacteria are key players in the colonization of bare soils and form assemblages with other microorganisms in the top millimetres, establishing biological soil crusts (biocrusts) that cover most soil surfaces in deserts, which have important roles in the functioning of drylands. However, knowledge of biocrusts from these extreme environments is limited. Therefore, to study cyanobacterial community composition in biocrusts from the Sahara Desert, we utilized a combination of methodologies in which taxonomic assignation, for next-generation sequencing of soil samples, was based on phylogenetic analysis (16S rRNA gene) in parallel with morphological identification of cyanobacteria in natural samples and isolates from certain locations. Two close locations that differed in microenvironmental conditions were analysed. One was a dry salt lake (a "chott"), and the other was an extension of sandy, slightly saline soil. Differences in cyanobacterial composition between the sites were found, with a clear dominance of Microcoleus spp. in the less saline site, while the chott presented a high abundance of heterocystous cyanobacteria as well as the filamentous non-heterocystous Pseudophormidium sp. and the unicellular cf. Acaryochloris. The cyanobacteria found in our study area, such as Microcoleus steenstrupii, Microcoleus vaginatus, Scytonema hyalinum, Tolypothrix distorta, and Calothrix sp., are also widely distributed in other geographic locations around the world, where the conditions are less severe. Our results, therefore, indicated that some cyanobacteria can cope with polyextreme conditions, as confirmed by bioassays, and can be considered extremotolerant, being able to live in a wide range of conditions.

Methane production by anaerobic co-digestion of mixed agricultural waste: cabbage and cauliflower.

Anaerobic co-digestion of residual cabbage and cauliflower mixed at a ratio 1:1 (w/w) was investigated in two continuously stirred tank reactors under mesophilic conditions to ensure stability and enhanced methane generation. The experiments, including start-up, inoculum acclimatisation and treatment of the waste mixture, were carried out over a 65-day period. The characterisation results showed that the residual mixture contained a high proportion of total Kjeldahl nitrogen (around 37 g N/kg dry weight). The maximum value of methanogenic yield potential was found to be 250 LSTP/kg VS (volatile solid) added, at STP conditions (0°C, 1 atm), by loading organic substrate at a concentration of 1 g VS/L, while its biodegradability was 60%. However, instability of the biomethanisation process was observed after 17 days, which might be a consequence of the high concentration of nitrogen in the reactors. The evaluation of the kinetics of the valorisation process revealed that the waste mixture studied can easily be biodegraded through anaerobic co-digestion.

Analysis of molecular diversity within single cyanobacterial colonies from environmental samples.

Attached or floating macroscopic cyanobacteria can be found in shallow waters and can be easily hand-collected, but their identification is often challenging due to their high morphological variability. In addition, many members of environmental samples lose their morphological adaptations under controlled conditions, making the integration of analyses of field populations and derived isolated cultures necessary in order to evaluate phenotypic plasticity for identification purposes. Therefore, in this study, twenty-nine macroscopic field samples were analyzed by Illumina sequencing and parallel optical microscopy. Some colonies showed the typical morphological characteristics of Rivularia biasolettiana, and others showed those of Rivularia haematites. However, other Rivularia-like colonies showed ambiguous morphologies, and some of them showed the phenotypic features of the new genus Cyanomargarita, which is virtually indistinguishable from Rivularia in the field. In all of the colonies, phylotype composition was highly heterogeneous, with abundances varying depending on the analyzed sample. Some colonies were dominated (97-99%) by a single phylotype, while in others, the percentage of the dominant phylotype decreased to approximately 50-60%. Surprisingly, the same dominant phylotype was found in R. biasolettiana and R. haematites colonies. The relationships between environmental and/or biological factors and morphological variability in these colonies are discussed.

Wastewater nutrient recovery using twin-layer microalgae technology for biofertilizer production.

This study evaluates the feasibility of advanced biofilm microalgae cultivation in a twin layer (TL) system for nutrient removal (N and P) as the tertiary treatment in small wastewater treatment plants (WWTPs) located in sensitive areas. Furthermore, the potential valorisation of microalgae biomass as a component of bio-based fertilizers is assessed. Scenedesmus sp. was chosen among 33 microalgae strains for inoculation of TL due to its high growth rate and its nutrient uptake capacity. The tests carried out in the prototype were markedly efficient for total soluble and ammoniacal nitrogen removal (up to 66 and 94%, respectively). In terms of potential valorisation of microalgae, the nutrient content was 5.5% N (over 40% protein), 8.8% P2O5 and 1.5% K2O, high enzymatic activity, very low levels of heavy metals and no detectable pathogen presence. However, in the formulation of solid-state bio-based fertilizers, the microalgae proportions in blends of over 2% of microalgae led to negative effects on ryegrass (Lolium perenne L. ssp.) and barley (Hordeum vulgare ssp.). The obtained results demonstrate that TL represents a promising technology, which allows efficient tertiary treatment of urban wastewater and the production of high-quality bio-based fertilizer.

Differences in the Cyanobacterial Community Composition of Biocrusts From the Drylands of Central Mexico. Are There Endemic Species?

In drylands worldwide, biocrusts, topsoil microbial communities, are prevalent, contributing to the biostabilization of soils and allowing the subsequent establishment and growth of vascular plants. In early successional biocrusts, cyanobacteria are the first dominant colonizers of bare ground, largely determining their functioning. However, there are large gaps in our knowledge of the cyanobacterial diversity in biocrusts, particularly in understudied geographic regions, such as the tropical latitudes. We analyzed the diversity of the cyanobacteria inhabiting the biocrusts of semideserts from Central Mexico in two localities belonging to the same desert system (Chihuahuan Desert) that are separated by a cordillera that crosses the center of Mexico. Morphological identification of the cyanobacteria was carried out after cultivation in parallel with the direct observation of the environmental samples and was supported by genetic characterization through analysis of the 16S rRNA gene of the isolated strains and by next-generation sequencing of the soil samples. Taxonomic assignment revealed a clear dominance of heterocystous cyanobacteria at one of the studied locations (Actopan, Hidalgo state). Although heterocystous forms were abundant at the other location (Atexcac, Puebla state), almost a third of the cyanobacterial phylotypes were represented by unicellular/colonial cyanobacteria, mostly Chroococcidiopsis spp. Only 28.4% of the phylotypes were found to be common to both soils. Most of the other taxa, however, were biocrust-type specific, and approximately 35% of the phylotypes were found to be unique to the soil they were collected in. In addition, differences in the abundances of the shared cyanobacteria between the locations were also found. These differences in the cyanobacterial distribution were supported by the distinct responses of the isolated strains representative of the sites to extreme heat and desiccation in bioassays. Some cyanobacteria with high abundance or only present at the hottest Actopan site, such as Scytonema hyalinum, Scytonema crispum, Nostoc commune, Nostoc sp., and Calothrix parietina, survived extreme heat and desiccation. However, Tolypothrix distorta and Chroococcidiopsis spp. were clearly sensitive to these extreme conditions in relation to their lower abundances at Actopan as opposed to Atexcac. Since novel biocrust-associated phylotypes were also found, the emergence of endemic cyanobacterial taxa is discussed.

Registro del Grupo NADYA-SENPE de Nutrición Enteral Domiciliaria en España; años 2016 y 2017 / Spanish home enteral nutrition registry of the year 2016 and 2017 from the NADYA-SENPE Group

Objetivo: exponer los resultados del registro de nutrición enteral domiciliaria (NED) de los años 2016 y 2017 del Grupo NADYA-SENPE. Material y métodos: se recopilaron los pacientes introducidos en el registro del 1 de enero al 31 de diciembre de 2016 y la mismas fechas de 2017 para proceder al análisis descriptivo y analítico de los datos. Resultados: en el año 2016 se obtuvieron 4.578 pacientes activos (prevalencia = 98,33 pacientes/millón de habitantes) y en 2017 fueron 4.777 (prevalencia = 102,57). Por sexos, hubo un 50,8% de varones en 2016 y un 50,5% en 2017. En el periodo 2016-17, la edad mediana fue de 71,5 años (IIQ 57-83); asimismo, finalizaron 1.558 episodios de NED y la causa principal fue el fallecimiento (793 pacientes, 50,89%). Los varones adultos fueron más jóvenes que las mujeres (65,3 vs. 73,3 años, p-valor < 0,001) y el diagnóstico más frecuente fue la enfermedad neurológica que cursa con afagia o disfagia severa (59%). La sonda nasogástrica (SNG) fue la vía de acceso más utilizada (48,3%) y se observa, además, que esta es la vía que se utiliza en los pacientes más ancianos (p < 0,001). Se registraron 126 pacientes pediátricos (57,1% niñas). La edad mediana de inicio de la NED fue de cuatro meses. Otras patologías fue el grupo diagnóstico más registrado (41,3%), seguido por la enfermedad neurológica que cursa con afagia o disfagia severa. Se alimentaban a través de gastrostomía en el 57,6% de los casos. Se observó que los niños más pequeños eran los que se alimentaban preferentemente por SNG (p-valor 0,001). Conclusiones: el número de pacientes del registro, así como el número de centros participantes, se va incrementando progresivamente. Las principales características de los pacientes no han variado. A pesar del aumento de posibilidades diagnósticas en la población pediátrica, llama la atención la clasificación dentro del grupo de Otras patologías

Objective: to present the results of the Spanish home enteral nutrition (HEN) registry of the NADYA-SENPE group for the year 2016 and 2017. Material and methods: from January 1st 2016 to December 31st 2017, the HEN registry was recorded and afterwards a further descriptive and analytical analysis was done. Results: in 2016, 4,578 active patients were recorded and prevalence was 98.33 patients per one million inhabitants; in 2017, 4,777 patients were recorded, with a prevalence of 102.57 per one million inhabitants; 50.8% were males in 2016 and 50.5% in 2017. During the period 2016-17, median age was 71.5 years (IIQ 57-83), 1,558 HEN episodes were finished and the main cause was death (793 patients, 50.89%). Adult males were younger than females (65.3 vs. 73.3 years, p-value < 0.001). The most frequent diagnosis was the neurological disorder that presents with aphagia or severe dysphagia (59%). Nasogastric tube was the most frequent administration route (48.3%) and it is the most widely used in elderly patients (p < 0.001). One hundred and twenty-six pediatric patients were registered (57.1% females). Median age at the beginning of HEN in children was four months. "Other disorders" was the most recorded diagnostic group (41.3%), followed by the group of neurological disorder that presents with aphagia or severe dysphagia. Regarding children, 57.6% were fed through gastrostomy and the younger ones were fed through nasogastric tube (p-value 0.001). Conclusions: the number of patients in the registry, as well as the number of participating centers, is progressively increasing. The main characteristics of the patients have not changed. Despite the increase in diagnostic possibilities in the pediatric population, the classification within the group of "Other pathologies" is quite significant

Polyphasic evaluation of key cyanobacteria in biocrusts from the most arid region in Europe.

Cyanobacteria are key microbes in topsoil communities that have important roles in preventing soil erosion, carbon and nitrogen fixation, and influencing soil hydrology. However, little is known regarding the identity and distribution of the microbial components in the photosynthetic assemblages that form a cohesive biological soil crust (biocrust) in drylands of Europe. In this study, we investigated the cyanobacterial species colonizing biocrusts in three representative dryland ecosystems from the most arid region in Europe (SE Spain) that are characterized by different soil conditions. Isolated cyanobacterial cultures were identified by a polyphasic approach, including 16S rRNA gene sequencing, phylogenetic relationship determination, and morphological and ecological habitat assessments. Three well-differentiated groups were identified: heterocystous-cyanobacteria (Nostoc commune, Nostoc calcicola, Tolypothrix distorta and Scytonema hyalinum), which play an important role in N and C cycling in soil; nonheterocystous bundle-forming cyanobacteria (Microcoleus steenstrupii, Trichocoleus desertorum, and Schizothrix cf. calcicola); and narrow filamentous cyanobacteria (Leptolyngbya frigida and Oculatella kazantipica), all of which are essential genera for initial biocrust formation. The results of this study contribute to our understanding of cyanobacterial species composition in biocrusts from important and understudied European habitats, such as the Mediterranean Basin, a hotspot of biodiversity, where these species are keystone pioneer organisms.

Cyanobacterial biocrust diversity in Mediterranean ecosystems along a latitudinal and climatic gradient.

Cyanobacteria are a key biotic component as primary producers in biocrusts, topsoil communities that have important roles in the functioning of drylands. Yet, major knowledge gaps exist regarding the composition of biocrust cyanobacterial diversity and distribution in Mediterranean ecosystems. We describe cyanobacterial diversity in Mediterranean semiarid soil crusts along an aridity gradient by using next-generation sequencing and bioinformatics analyses, and detect clear shifts along it in cyanobacterial dominance. Statistical analyses show that temperature and precipitation were major parameters determining cyanobacterial composition, suggesting the presence of differentiated climatic niches for distinct cyanobacteria. The responses to temperature of a set of cultivated, pedigreed strains representative of the field populations lend direct support to that contention, with psychrotolerant vs thermotolerant physiology being strain dependent, and consistent with their dominance along the natural gradient. Our results suggest a possible replacement, as global warming proceeds, of cool-adapted by warm-adapted nitrogen-fixing cyanobacteria (such as Scytonema) and a switch in the dominance of Microcoleus vaginatus by thermotolerant, novel phylotypes of bundle-forming cyanobacteria. These differential sensitivities of cyanobacteria to rising temperatures and decreasing precipitation, their ubiquity, and their low generation time point to their potential as bioindicators of global change.

Aproximación al desarrollo de un índice de fragilidad basado en la valoración integral geriátrica en centros sociosanitarios / A first approach to the development of a fragilty index based on comprehensive geriatric assessment in nursing homes

Objetivo: Realizar una aproximación al desarrollo de un índice de fragilidad en centros sociosanitarios y analizar su posible repercusión en el desarrollo de una farmacoterapia adecuada a la situación del paciente. Método: El índice de fragilidad se elaboró a partir de la información incluida en la valoración integral geriátrica y se aplicó de forma retrospectiva a los pacientes de dos centros a partir de la última valoración de cada uno de ellos. Resultados: Se seleccionaron 17 variables, que incluyeron 27 déficits. El análisis se realizó a 269 pacientes (edad media, 82,9 ± 8,8 años). El índice de fragilidad consideró frágiles al 86% de los pacientes, estando el 60% de estos en un nivel de fragilidad moderado-avanzado. Conclusiones: El índice de fragilidad resulta sencillo, rápido de aplicar y parece tener capacidad discriminatoria en la cuantificación del grado de fragilidad, pudiendo ser de ayuda para establecer la intensidad terapéutica más adecuada para cada paciente

Objective: To carry out an approach for the development of a frailty index in nursing homes and to analize its potential use in order to individualize the pharmacological treatment. Method: The frailty index was constructed from the information included in the comprehensive geriatric assessment established in nursing homes. The index has been retrospectively applied to the patients of two centers using the last comprehensive geriatric assessment of each one. Results: 17 variables that included 27 deficits were selected and classified in 4 domains. 269 patients (mean age 82.9 ± 8.8 years) were included in the analysis. The frailty index indicated that 86% of patients should be considered frail and 60% of these to moderate-advanced level. Conclusions: The frailty index is simple and quick to apply. It seems to have discriminative capacity in terms of quantifying the degree of frailty and it could be useful in prescribing the most appropriate therapeutic aggressiveness to each patient

Diversity of biocrust-forming cyanobacteria in a semiarid gypsiferous site from Central Spain.

Cyanobacteria are a key constituent of biocrusts, communities dominated by lichens, mosses and associated microorganisms, which are prevalent in drylands worldwide and that largely determine their functioning. Despite their importance, there are large gaps in our knowledge of the composition and diversity of cyanobacteria associated with biocrusts, particularly in areas such as the Mediterranean Basin. We studied the diversity of these cyanobacteria in a gypsiferous grassland from Central Spain using both morphological identification after cultivation and genetic analyses with the 16S rRNA gene. Nine different morphotypes were observed, eight corresponding to filamentous, and one to unicellular cyanobacteria. We found cyanobacterial genera typical of biocrust communities, such as Microcoleus and Trichocoleus, and N-fixing cyanobacteria such as Scytonema and Nostoc. Genetic information allowed us to identify cultures belonging to recently described genera such as Roholtiella, Nodosilinea and Mojavia. We also describe two new phylotypes of Microcoleus and Scytonema, which are key genera contributing to ecosystem functioning in biocrust-dominated ecosystems worldwide.

Curva de aprendizaje de la punción aspiración con aguja fina de tiroides / Learning curve of thyroid fine-needle aspiration biopsy

Introducción: La punción-aspiración con aguja fina (PAAF) es la técnica de referencia en la evaluación de los pacientes con nódulos tiroideos. Su mayor limitación son las muestras inadecuadas, que deberían ser menos del 20% de los casos. Objetivo: Analizar la curva de aprendizaje de dicha técnica de un endocrinólogo sin experiencia (endocrinólogo 2), comparando sus resultados con los obtenidos en los mismos nódulos por un colega experimentado (endocrinólogo 1). Material y métodos: Se realizaron 60 PAAF entre los meses de febrero y junio de 2016. Cada endocrinólogo realizó 2punciones de cada nódulo en un orden establecido aleatorizadamente. El orden de las punciones y el endocrinólogo que las realizaba eran datos desconocidos para la patóloga que analizó las muestras. Resultados: En el total de las PAAF, el endocrinólogo 1 tuvo un porcentaje de diagnósticos significativamente superior al endocrinólogo 2 (82 vs. 72%; p=0,015). En las primeras 20 PAAF la diferencia entre ambos fue notable y estadísticamente significativa (80 vs. 50%; p=0,047). En las siguientes 20 PAAF la diferencia se redujo y ya no tenía significación estadística (90 vs. 65%; p=0,058). Y en las últimas 20 la diferencia fue mínima y sin significación estadística (75 vs. 70%; p=0,723). Conclusiones: La curva de aprendizaje de la eco-PAAF puede completarse en un entorno adecuado haciéndola un mínimo de 60 veces. Aunque las guías recomiendan al menos 3punciones por nódulo, 2son suficientes para conseguir un porcentaje adecuado de diagnósticos (AU)

Background: Fine-needle aspiration biopsy (FNAB) is the reference procedure for thyroid nodule evaluation. Its main limitation are inadequate samples, which should be less than 20%. Objective: To analyze the learning curve of the procedure by comparing the results of a non-experienced endocrinologist (endocrinologist 2) to those of an experienced one (endocrinologist 1). Material and methods: Sixty FNABs were analyzed from February to June 2016. Each endocrinologist made 2punctures of every nodule in a random order. This order and the professional making every puncture were unknown to the pathologist who examined the samples. Results: Endocrinologist 1 had a higher percentage of diagnoses than endocrinologist 2 (82% vs. 72%, P=.015). In the first 20 FNABs, the difference between both physicians was remarkable and statistically significant (80% vs. 50%, P=.047). In the following 20 FNABs, the difference narrowed and was not statistically significant (90% vs. 65%, P=.058). In the final 20 FNABs, the difference was minimal and not statistically significant (75% vs. 70%, P=.723). Conclusions: The learning curve of ultrasound-guided FNAB may be completed in a suitable environment by performing it at least 60 times. Although the guidelines recommend at least 3punctures per nodule, 2are enough to achieve an accurate percentage of diagnoses (AU)

Learning curve of thyroid fine-needle aspiration biopsy. / Curva de aprendizaje de la punción aspiración con aguja fina de tiroides.

BACKGROUND: Fine-needle aspiration biopsy (FNAB) is the reference procedure for thyroid nodule evaluation. Its main limitation are inadequate samples, which should be less than 20%. OBJECTIVE: To analyze the learning curve of the procedure by comparing the results of a non-experienced endocrinologist (endocrinologist 2) to those of an experienced one (endocrinologist 1). MATERIAL AND METHODS: Sixty FNABs were analyzed from February to June 2016. Each endocrinologist made 2punctures of every nodule in a random order. This order and the professional making every puncture were unknown to the pathologist who examined the samples. RESULTS: Endocrinologist 1 had a higher percentage of diagnoses than endocrinologist 2 (82% vs. 72%, P=.015). In the first 20 FNABs, the difference between both physicians was remarkable and statistically significant (80% vs. 50%, P=.047). In the following 20 FNABs, the difference narrowed and was not statistically significant (90% vs. 65%, P=.058). In the final 20 FNABs, the difference was minimal and not statistically significant (75% vs. 70%, P=.723). CONCLUSIONS: The learning curve of ultrasound-guided FNAB may be completed in a suitable environment by performing it at least 60 times. Although the guidelines recommend at least 3punctures per nodule, 2are enough to achieve an accurate percentage of diagnoses.

Protective Effect of Silybum marianum and Silibinin on Endothelial Cells Submitted to High Glucose Concentration.

Silybum marianum Gaertn. (Milk thistle) has been used since ancient times for the relief of liver diseases characterized by intense oxidative stress such as inflammatory liver disease and cirrhosis. As oxidative stress by hyperglycemia is involved in micro- and macrovascular complications of type 2 diabetes, our aim was to assess the protective effect of milk thistle seed extract against oxidative stress induced by a high glucose concentration on endothelial cells (EA.hy926 cells). High-performance liquid chromatographic analysis shows flavonolignans silychristin and silibinin A and B as major components. No cell toxicity was observed for concentrations up to 100 µg/mL of milk thistle extract for 24 h. Concentrations of 5-25 µg/mL of the extract were used to assess the protective effect on EA.hy926 cells treated with 30 mM glucose for 24 h. Oxidative damage by 30 mM glucose was shown as a significant decrease in reduced glutathione and a significant increase in protein carbonyls and antioxidant enzyme activities. S. marianum extract recovered reduced glutathione and balanced the elevated carbonyls and enzyme activity. Silibinin alone also recovered reduced glutathione and antioxidant enzymes. S. marianum protects endothelial cell against oxidative damage by modulating antioxidant enzyme activity, reduced glutathione, and protein carbonyl levels.

Nitrogen fixation in a non-heterocystous cyanobacterial mat from a mountain river.

In situ nitrogen fixation was investigated in a cyanobacterial mat growing on the bed of rocks of the Muga River, Spain. The filamentous non-heterocystous cyanobacterium Schizothrix dominated the mat, showing nitrogenase activity in the light at similar rates to those found in nearby heterocystous Rivularia colonies. N2 fixation in the light was significantly increased by an inhibitor of PSII and oxygen evolution, DCMU (3-[3,4-dichlorophenyl]-1,1-dimethylurea), and anaerobic conditions. However, no nitrogenase activity was found in the dark. Addition of fructose as a respiratory substrate induced nitrogenase activity in samples incubated under aerobic conditions in the dark but not in anaerobic conditions. Microelectrode oxygen profiles showed internal microaerobic microzones where nitrogen fixation might concentrate. Analyses of the 16S rRNA gene revealed only the presence of sequences belonging to filamentous non-heterocystous cyanobacteria. nifH gene diversity showed that the major phylotypes also belonged to this group. One of the three strains isolated from the Schizothrix mat was capable of fixing N2 and growing in the absence of combined N. This was consistent with the nifH gene analysis. These results suggest a relevant contribution of non-heterocystous cyanobacteria to nitrogen fixation in these mats.

Anaerobic co-digestion of sewage sludge and strawberry extrudate under mesophilic conditions.

The biomethanization of sewage sludge has several disadvantages such as low methane yield, poor biodegradability and nutrient imbalance. In this paper, a sewage sludge and strawberry extrudate mixture in a proportion of 40:60 (wet weight) is proposed to improve the viability of the process. The addition of an easily biodegradable co-substrate enhanced the nutrient balance and diluted the heavy metals and inhibitors from sewage sludge. Two different experimental set-ups at lab and semi-pilot scale were employed in order to ensure the reproducibility and significance of the obtained values. Co-digestion improved the stability of the process by decreasing the alkalinity to a mean value of 3215 ± 190 mg CaCO3/L, while maintaining the pH within the optimal range for anaerobic digestion. The methane yield coefficient and biodegradability were 176 L/kg VS (total volatile solids) (0°C, 1 atm) and 81% (VS), respectively. Kinetic parameters decreased at the highest loads, suggesting the occurrence of a slowing down phenomenon. A quality organic amendment with a heavy metal content lower than the limits established under European legislation for agricultural applications was obtained from the digestate of the proposed treatment.

Characterization and responses to environmental cues of a photosynthetic antenna-deficient mutant of the filamentous cyanobacterium Anabaena sp. PCC 7120.

The cyanobacterial phycobilisome (PBS) is a giant pigment-protein complex which harvests light energy for photosynthesis and comprises two structures: a core and peripheral rods. Most studies on PBS structure and function are based on mutants of unicellular strains. In this report, we describe the phenotypic and genetic characterization of a transposon mutant of the filamentous Anabaena sp. strain PCC 7120, denoted LC1, which cannot synthesize the phycobiliprotein phycocyanin (PC), the main component of the rods; in this mutant, the transposon had inserted into the cpcB gene (orf alr0528) which putatively encodes PC-ß chain. Mutant LC1 was able to synthesize phycoerythrocyanin (PEC), a phycobiliprotein (PBP) located at the terminal region of the rods; but in the absence of PC, PEC did not attach to the PBSs that only retained the allophycocyanin (APC) core; ferredoxin: NADP+-oxidoreductase (FNR) that is associated with the PBS in the wild type, was not found in isolated PBSs from LC1. The performance of the mutant exposed to different environmental conditions was evaluated. The mutant phenotype was successfully complemented by cloning and transfer of the wild type complete cpc operon to mutant LC1. Interestingly, LC1 compensated its mutation by significantly increasing the number of its core-PBS and the effective quantum yield of photosystem II (PSII) photochemistry; this feature suggests a more efficient energy conversion in the mutant which may be useful for biotechnological applications.

Optimization of anaerobic co-digestion of strawberry and fish waste.

Anaerobic co-digestion of agri-food waste is a promising management alternative. Its implementation, however, requires evaluating the proportion in which waste should be mixed to optimize their centralized treatment. The combined treatment of strawberry extrudate and fish waste, which are widely generated in Mediterranean areas, was optimized. Strawberry extrudate and fish waste were mixed and treated at different proportions (88:12, 94:6, and 97:3, respectively; wet basis). The proportions selected for the mixture allow the different flows to be absorbed simultaneously. The highest methane production was observed for the ratio 94:6 (0.205 m(3) STP CH4/kg volatile solid) (VS) (STP; 0 °C, 1 atm), with a methane production rate in the range of 5 · 10(-3)-9 · 10(-3) m(3) STP/kg VS · d, while the highest organic loading rate was observed for the mixture at a proportion 88:12 (1.9 ± 0.1 kg VS/m(3) · d). Biodegradability was found to be similar for the 88:12 and 94:6 proportions, with values around 90 % in VS. Nevertheless, the 97:3 ratio was not viable due to a low methane production. An inhibition phenomenon occurred at increasing loads due to the effect of some compounds contained in the fish waste such as chloride or nitrogen.