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The survival of an organism relies on its ability to repair the damage caused by trauma, toxic agents, and inflammation. This process involving cell proliferation and differentiation is driven by several growth factors and is critically dependent on the organization of the extracellular matrix. Since autologous platelet concentrates (APCs) are fibrin matrices in which cells, growth factors, and cytokines are trapped and delivered over time, they are able to influence that response at different levels. The present review thoroughly describes the molecular components present in one of these APCs, leukocyte- and platelet-rich fibrin (L-PRF), and summarizes the level of evidence regarding the influence of L-PRF on anti-inflammatory reactions, analgesia, hemostasis, antimicrobial capacity, and its biological mechanisms on bone/soft tissue regeneration.
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Large-scale genomic studies have significantly increased our knowledge of genetic variability across populations. Regional genetic profiling is essential for distinguishing common benign variants from disease-causing ones. To this end, we conducted a comprehensive characterization of exonic variants in the population of Navarre (Spain), utilizing whole genome sequencing data from 358 unrelated individuals of Spanish origin. Our analysis revealed 61,410 biallelic single nucleotide variants (SNV) within the Navarrese cohort, with 35% classified as common (MAF > 1%). By comparing allele frequency data from 1000 Genome Project (excluding the Iberian cohort of Spain, IBS), Genome Aggregation Database, and a Spanish cohort (including IBS individuals and data from Medical Genome Project), we identified 1069 SNVs common in Navarre but rare (MAF ≤ 1%) in all other populations. We further corroborated this observation with a second regional cohort of 239 unrelated exomes, which confirmed 676 of the 1069 SNVs as common in Navarre. In conclusion, this study highlights the importance of population-specific characterization of genetic variation to improve allele frequency filtering in sequencing data analysis to identify disease-causing variants.
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Frecuencia de los Genes , Polimorfismo de Nucleótido Simple , Humanos , España , Polimorfismo de Nucleótido Simple/genética , Secuenciación Completa del Genoma , Masculino , Femenino , Genética de Población , Variación Genética , Genoma Humano , Exoma/genética , Estudios de CohortesRESUMEN
Se exponen los hallazgos históricos y la importancia biológica de los telómeros en la vida celular y en los aspectos genéticos del ADN humano. (AU)
The discovery and the biological importance of the telomeres are exposed. (AU)
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Humanos , ADN/genética , Telómero/fisiología , Telómero/genética , Telomerasa/fisiología , Telomerasa/genética , Envejecimiento/fisiología , ADN/metabolismo , Senescencia Celular , Telomerasa/metabolismo , Replicación del ADN/fisiología , Acortamiento del Telómero , Neoplasias/fisiopatologíaRESUMEN
BACKGROUND: Metalloproteinases (MMPs) have been reported to be related to oncologic outcomes. The main goal of the study was to study the relationship between these proteins and the long-term prognosis of patients undergoing oncologic lung resection surgery. METHODS: This was a substudy of the phase IV randomized control trial (NCT02168751). We analyzed MMP-2, -3, -7, and -9 in blood samples and bronchoalveolar lavage (LBA) and the relationship between MMPs and long postoperative outcomes (survival and disease-free time of oncologic recurrence). RESULTS: Survival was longer in patients who had lower MMP-2 levels than those with higher MMP-2 in blood samples taken 6 h after surgery (6.8 vs. 5.22 years; p = 0.012) and MMP-3 (6.82 vs. 5.35 years; p = 0.03). In contrast, survival was longer when MMP-3 levels were higher in LBA from oncologic lung patients than those with lower MMP-3 (7.96 vs. 6.02 years; p = 0.005). Recurrence-free time was longer in patients who had lower MMP-3 levels in blood samples versus higher (5.97 vs. 4.23 years; p = 0.034) as well as lower MMP-7 (5.96 vs. 4.5 years; p = 0.041) or lower MMP-9 in LBA samples (6.21 vs. 4.18 years; p = 0.012). CONCLUSION: MMPs were monitored during the perioperative period of oncologic lung resection surgery. These biomarkers were associated with mortality and recurrence-free time. The role of the different MMPs analyzed during the study do not have the same prognostic implications after this kind of surgery.
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Metaloproteinasa 2 de la Matriz , Metaloproteinasa 3 de la Matriz , Humanos , Pronóstico , Pulmón , BiomarcadoresRESUMEN
Epilepsy is a neurological disorder (the third most common, following stroke and migraines). A key aspect of its diagnosis is the presence of seizures that occur without a known cause and the potential for new seizures to occur. Machine learning has shown potential as a cost-effective alternative for rapid diagnosis. In this study, we review the current state of machine learning in the detection and prediction of epileptic seizures. The objective of this study is to portray the existing machine learning methods for seizure prediction. Internet bibliographical searches were conducted to identify relevant literature on the topic. Through cross-referencing from key articles, additional references were obtained to provide a comprehensive overview of the techniques. As the aim of this paper aims is not a pure bibliographical review of the subject, the publications here cited have been selected among many others based on their number of citations. To implement accurate diagnostic and treatment tools, it is necessary to achieve a balance between prediction time, sensitivity, and specificity. This balance can be achieved using deep learning algorithms. The best performance and results are often achieved by combining multiple techniques and features, but this approach can also increase computational requirements.
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Aprendizaje Profundo , Epilepsia , Humanos , Electroencefalografía , Convulsiones/diagnóstico , Epilepsia/diagnóstico , Aprendizaje Automático , AlgoritmosRESUMEN
Los murciélagos son mamíferos vertebrados presentes en la Ciudad de Buenos Aires, estimándose una población de 4 animales por habitante. Son portadores de varias enfermedades importantes y además empeoran las condiciones respiratorias de enfermos crónicos. En el campo cumplen una interesante función, ya que se alimentan de insectos perjudiciales para las siembras. El guano puede ser útil en el abono de la tierra debido al aporte de carbono y nitrógeno. En las ciudades su presencia tiene consecuencias diferentes. Se encuentran en los taparrollos de las habitaciones, así como también en todas las oquedades de muros, árboles, grietas, etc. Se exponen aquí los peligros y los cuidados que deben tenerse en la Ciudad de Buenos Aires ante la invasión de estos quirópteros. (AU)
Bats are vertebrate mammals present in the City of Buenos Aires, with an estimated population of 4 animals per inhabitant. They are carriers of several important diseases and also worsen the respiratory conditions of the chronically ill. In rural areas they fulfill an interesting function, since they feed on insects harmful to crops. Guano can be useful in soil fertilization due to its contribution of carbon and nitrogen. In cities their presence has different consequences. They are found in the roll covers of the rooms as well as in all the hollows of walls, trees, cracks, etc. The dangers and precautions to be taken in the city of Buenos Aires in the face of the invasion of these chiroptera are described here. (AU)
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Humanos , Animales , Masculino , Femenino , Adulto , Persona de Mediana Edad , Quirópteros/inmunología , Rinitis Alérgica Perenne/etiología , Antígenos Dermatofagoides , Alérgenos Animales/inmunología , Argentina , Inmunoensayo/métodos , Salud Urbana , Ciudades , Heces/químicaRESUMEN
SARS-CoV-2 infection (COVID-19) has had a significant impact on transplant activity in our country. Mortality and the risk of complications associated with COVID-19 in kidney transplant recipients (KT) were expected to be higher due to their immunosuppressed condition and the frequent associated comorbidities. Since the beginning of the pandemic in March 2020 we have rapidly improved our knowledge about the epidemiology, clinical features and management of COVID-19 post-transplant, resulting in a better prognosis for our patients. KT units have been able to adapt their programs to this new reality, normalizing both donation and transplantation activity in our country. This manuscript presents a proposal to update the general recommendations for the prevention and treatment of infection in this highly vulnerable population such as KT.
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COVID-19 , Trasplante de Riñón , Humanos , COVID-19/epidemiología , SARS-CoV-2 , Pandemias/prevención & control , ComorbilidadRESUMEN
La infección por el SARS-CoV-2 (COVID-19) ha supuesto un importante impacto en la actividad trasplantadora en nuestro país. Era esperable que la mortalidad y el riesgo de complicaciones asociadas a la COVID-19 en el receptor de trasplante renal (TR) fueran mayores debido a su condición de inmunosupresión y a las frecuentes comorbilidades asociadas. Desde el inicio de la pandemia en marzo del 2020 hemos mejorado rápidamente nuestro conocimiento acerca de la epidemiología, características clínicas y manejo de la COVID-19 postrasplante, redundando en un mejor pronóstico para nuestros pacientes. Las unidades de TR han sabido adaptar sus programas a esta nueva realidad, normalizándose la actividad tanto de donación como de trasplante en nuestro país. Este manuscrito presenta una propuesta de actualización de las recomendaciones generales para la prevención y el tratamiento de la infección en esta población tan vulnerable como son los receptores de un trasplante renal. (AU)
SARS-CoV-2 infection (COVID-19) has had a significant impact on transplant activity in our country. Mortality and the risk of complications associated with COVID-19 in kidney transplant (KT) recipients were expected to be higher due to their immunosuppressed condition and the frequent associated comorbidities. Since the beginning of the pandemic in March 2020 we have rapidly improved our knowledge about the epidemiology, clinical features and management of COVID-19 post-transplant, resulting in a better prognosis for our patients. KT units have been able to adapt their programs to this new reality, normalizing both donation and transplantation activity in our country. This manuscript presents a proposal to update the general recommendations for the prevention and treatment of infection in this highly vulnerable population such as KT. (AU)
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Humanos , Trasplante de Riñón , Pandemias , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/prevención & control , Infecciones por Coronavirus/complicaciones , Infecciones por Coronavirus/tratamiento farmacológico , Vacunación Masiva , Coronavirus Relacionado al Síndrome Respiratorio Agudo SeveroRESUMEN
Introduction: Calcium is essential for the correct functioning of the central nervous system, and calcium-binding proteins help to finely regulate its concentration. Whereas some calcium-binding proteins such as calmodulin are ubiquitous and are present in many cell types, others such as calbindin, calretinin, and parvalbumin are expressed in specific neuronal populations. Secretagogin belongs to this latter group and its distribution throughout the brain is only partially known. In the present work, the distribution of secretagogin-immunopositive cells was studied in the entire brain of healthy adult mice. Methods: Adult male C57BL/DBA mice aged between 5 and 7 months were used. Their whole brain was sectioned and used for immunohistochemistry. Specific neural populations were observed in different zones and nuclei identified according to Paxinos mouse brain atlas. Results: Labelled cells were found with a Golgi-like staining, allowing an excellent characterization of their dendritic and axonal arborizations. Many secretagogin-positive cells were observed along different encephalic regions, especially in the olfactory bulb, basal ganglia, and hypothalamus. Immunostained populations were very heterogenous in both size and distribution, as some nuclei presented labelling in their entire extension, but in others, only scattered cells were present. Discussion: Secretagogin can provide a more complete vision of calcium-buffering mechanisms in the brain, and can be a useful neuronal marker in different brain areas for specific populations.
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Objective. The compromise of the hippocampal loop is a hallmark of mesial temporal lobe epilepsy (MTLE), the most frequent epileptic syndrome in the adult population and the most often refractory to medical therapy. Hippocampal sclerosis is found in >50% of drug-refractory MTLE patients and primarily involves the CA1, consequently disrupting the hippocampal output to the entorhinal cortex (EC). Closed-loop deep brain stimulation is the latest frontier to improve drug-refractory MTLE; however, current approaches do not restore the functional connectivity of the hippocampal loop, they are designed by trial-and-error and heavily rely on seizure detection or prediction algorithms. The objective of this study is to evaluate the anti-ictogenic efficacy and robustness of an artificial bridge restoring the dialog between hippocampus and EC.Approach. In mouse hippocampus-EC slices treated with 4-aminopyridine and in which the Schaffer Collaterals are severed, we established an artificial bridge between hippocampus and EC wherein interictal discharges originating in the CA3 triggered stimulation of the subiculum so to entrain EC networks. Combining quantification of ictal activity with tools from information theory, we addressed the efficacy of the bridge in controlling ictogenesis and in restoring the functional connectivity of the hippocampal loop.Main results. The bridge significantly decreased or even prevented ictal activity and proved robust to failure; when operating at 100% of its efficiency (i.e., delivering a pulse upon each interictal event), it recovered the functional connectivity of the hippocampal loop to a degree similar to what measured in the intact circuitry. The efficacy and robustness of the bridge stem in mirroring the adaptive properties of the CA3, which acts as biological neuromodulator.Significance. This work is the first stepping stone toward a paradigm shift in the conceptual design of stimulation devices for epilepsy treatment, from function control to functional restoration of the salient brain circuits.
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Epilepsia Refractaria , Epilepsia del Lóbulo Temporal , Ratones , Animales , Sistema Límbico , Hipocampo/fisiología , Convulsiones/terapia , Corteza Entorrinal , Epilepsia del Lóbulo Temporal/terapiaRESUMEN
INTRODUCTION: Chronic thromboembolic pulmonary hypertension (CTEPH) is a long-term sequel to pulmonary embolism (PE) whose incidence varies according to different published studies. We have carried out this study to determine its incidence within 2 years after index pulmonary embolism and to study limitations to an early diagnosis. MATERIAL AND METHODS: OSIRIS is a multicentre, longitudinal cohort study. Patients were followed for 3, 6, 12, and 24 months after pulmonary embolism using a structured three-step algorithm. A physician-centered questionnaire at least one positive response in a screening proceeded to the second step, transthoracic echocardiography. The third step consisted of ventilation/perfusion lung scintigraphy and right heart catheterisation. A transthoracic echocardiography was performed in patients without positive response in the screening questionnaire after 2 years. CTEPH diagnosis required haemodynamic confirmation by right heart catheterisation and mismatched perfusion defects on lung scintigraphy. RESULTS: A total of 1191 patients were enrolled in 18 Spanish hospitals. Cumulative CTEPH incidence after 2-years PE was: 2.49 % (95 % CI: 1.68-3.56) and the incidence rate of CTEPH was 1.1 cases per 1000 person-months (95 % CI: 0.725; 1.60). The CTEPH algorithm presented a lack of adherence of 29 %; patient and physician preferences posed barriers to the triage algorithm The screening questionnaire, in patients who completed the follow-up, shows a specificity of 91.3 % (89.0-93.2 %) and negative predictive value of 99.4 % (98.4-99.8 %).. CONCLUSIONS: OSIRIS provides practiced clinical based data on the chronic thromboembolic pulmonary hypertension incidence and identified barriers to the implementation of a 3-step triage algorithm for its detection. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT03134898.
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Hipertensión Pulmonar , Embolia Pulmonar , Humanos , Hipertensión Pulmonar/etiología , Estudios Longitudinales , Estudios de Factibilidad , Embolia Pulmonar/complicaciones , Embolia Pulmonar/diagnóstico , Embolia Pulmonar/epidemiología , Algoritmos , Enfermedad CrónicaRESUMEN
Los autores describen los hechos que dieron lugar al nacimiento, en 1872, de la SCA, que cumplió 150 años de existencia. Se señalan sus fundadores, sus objetivos y los principales hitos a lo largo de ese tiempo. El análisis hace hincapié en que durante la primera mitad de ese período solo un presidente fue médico: los demás fueron ingenieros, físicos, químicos, militares, abogados e investigadores naturalistas. En cambio, durante la segunda mitad 8 médicos, de distintas especialidades, ocuparon la presidencia, todos con una destacada actuación profesional, tanto nacional como internacional, y que aportaron una característica especial a la institución, propia de esta profesión. (AU)
The authors describe the events that led to the birth, in 1872, of the SCA, which celebrated 150 years of existence. Its founders, its objectives and the main milestones throughout that time are indicated. The analysis emphasizes that during the first half of that period only one president was a doctor: the others were engineers, physicists, chemists, soldiers, lawyers, and naturalistic researchers. On the other hand, during the second half, 8 doctors, from different specialties, held the presidency, all with an outstanding professional performance, both nationally and internationally, and who contributed a special characteristic to the institution, typical of this profession. (AU)
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Historia del Siglo XIX , Historia del Siglo XX , Médicos/historia , Sociedades Científicas/historia , Argentina , Historia de la Medicina , Aniversarios y Eventos EspecialesRESUMEN
In vitro experiments have shown that the E2 protein of human papillomaviruses (HPV) binds to the upstream regulatory region (URR) of the viral genome and modulates transcription. Additionally, it seems to be a necessary component for viral DNA replication together with E1. We have developed a transgenic mouse model containing the URR region of the low-risk virus HPV11 that regulates the expression of the lacZ reporter gene. Most interestingly, in these mice, the transgene was exclusively expressed in the bulge region of the hair follicle but not in any other tissues. Further experimental data indicate that in double transgenic mice that also express the HPV11-E2 protein under the control of the Ubiquitin C-promoter, the transcription of the reporter gene is modulated. When E2 is present, the expression of the reporter gene also occurs exclusively in the bulge region of the hair follicles as it does in the single transgenic mice, but the expression of the lacZ driven by the URR is increased and the statistical spread is greater. Even if the expression of the reporter gene occurs in the hair follicles of the dorsal skin of an animal uniform, E2 obviously has the capacity for both to induce and to repress the URR activity in vivo.
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Replicación del ADN , Replicación Viral , Ratones , Animales , Humanos , ADN Viral/metabolismo , Regiones Promotoras Genéticas , Ratones TransgénicosRESUMEN
Introduction and objectives: Graft outcomes in pancreas transplantation have improved in recent decades, but data are mainly derived from registries or prospective single-centre studies. This large epidemiological study was undertaken to investigate the impact of clinical and demographic factors on graft and patient survival in pancreas transplant recipients in Spain, and to provide robust, country-wide, practice-based data to complement registry findings. Patients and methods: We conducted a retrospective, longitudinal, epidemiological study to assess risk factors impacting patient and graft survival in pancreas transplant recipients in eight centres in Spain. All patients transplanted between 1 January 2008 and 31 December 2012 were included; data were collected until 31 December 2015. The KaplanMeier method was used for all time-to-event analyses, including patient survival, graft survival, acute rejection, and BPAR. For graft survival analysis, in cases of death with functioning graft, patients were censored without any event on the date of death. For acute rejection and BPAR, patients were censored without any event on the date of death or graft loss. Univariable and multivariable analyses (Cox proportional hazards model) were conducted to assess the association between baseline clinical and demographic characteristics and patient/graft survival. (AU)
Introducción y objetivos: Los resultados del injerto en el trasplante de páncreas han mejorado en las últimas décadas, pero los datos provienen principalmente de registros o estudios prospectivos unicéntricos. Este estudio epidemiológico se llevó a cabo para investigar el impacto de los factores clínicos y demográficos en la supervivencia del injerto y del paciente en receptores de trasplante de páncreas en España, y proporcionar datos sólidos, basados en la práctica a nivel nacional, para complementar los hallazgos de los registros. Pacientes y métodos: Realizamos un estudio epidemiológico longitudinal, retrospectivo, para evaluar los factores de riesgo que influyen en la supervivencia del paciente y del injerto en receptores de trasplante de páncreas en 8 centros de España. Se incluyeron todos los pacientes trasplantados entre el 1 de enero de 2008 y el 31 de diciembre de 2012; los datos se recogieron hasta el 31 de diciembre de 2015. Se utilizó el método de Kaplan-Meier para todos los análisis del tiempo transcurrido hasta el evento, incluida la supervivencia del paciente, la supervivencia del injerto, el rechazo agudo y el BPAR. Para el análisis de la supervivencia del injerto, en los casos de muerte con injerto funcionante, los pacientes fueron censurados sin ningún evento en la fecha de la muerte. Para el rechazo agudo y BPAR, los pacientes fueron censurados sin ningún evento en la fecha de la muerte o pérdida del injerto. Se realizaron análisis univariables y multivariables (modelo de riesgos proporcionales de Cox) para evaluar la asociación entre las características clínicas y demográficas basales y la supervivencia del paciente/injerto. (AU)
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Humanos , Masculino , Femenino , Adulto Joven , Adulto , Supervivencia , Trasplante de Páncreas , Trasplante de Riñón , Estudios Epidemiológicos , Estudios Retrospectivos , España , Enfermedades Cardiovasculares , Enfermedades RenalesRESUMEN
INTRODUCTION AND OBJECTIVES: Graft outcomes in pancreas transplantation have improved in recent decades, but data are mainly derived from registries or prospective single-centre studies. This large epidemiological study was undertaken to investigate the impact of clinical and demographic factors on graft and patient survival in pancreas transplant recipients in Spain, and to provide robust, country-wide, practice-based data to complement registry findings. PATIENTS AND METHODS: We conducted a retrospective, longitudinal, epidemiological study to assess risk factors impacting patient and graft survival in pancreas transplant recipients in eight centres in Spain. All patients transplanted between 1 January 2008 and 31 December 2012 were included; data were collected until 31 December 2015. The Kaplan-Meier method was used for all time-to-event analyses, including patient survival, graft survival, acute rejection, and BPAR. For graft survival analysis, in cases of death with functioning graft, patients were censored without any event on the date of death. For acute rejection and BPAR, patients were censored without any event on the date of death or graft loss. Univariable and multivariable analyses (Cox proportional hazards model) were conducted to assess the association between baseline clinical and demographic characteristics and patient/graft survival. RESULTS: Data were included for 241 (80.1%) simultaneous pancreas-kidney transplants, 56 (18.6%) pancreas-after-kidney transplants and 4 (1.3%) pancreas transplants alone. Mean±standard deviation time from diagnosis until transplantation was 26.1±7.5 years. Nineteen patients died, mainly due to infections (n=10); the remaining 282 patients (93.7%) survived from transplantation until the end of the study. Among 55 patients (18.3%) with pancreas graft loss, the main reasons were vascular thrombosis (n=19), chronic rejection (n=10), acute rejection (n=6) and death with a functioning graft (n=5). The overall rate of vascular-related death was 1.3% at 5 years post transplant. Univariable analysis showed that patient age and weight, donor age, previous kidney transplantation, previous cardiovascular events and need for insulin more than 48h post transplantation were significantly associated with pancreas graft survival. Of these, in multivariable analyses pancreas graft survival was inferior in patients who had received a previous kidney transplant prior to pancreas transplantation (log-rank test, p=0.0002). Glucose metabolism, renal function and cardiovascular risk factors were generally stable following transplantation. CONCLUSIONS: The results of this multicentre study highlight the excellent patient and graft outcomes following pancreas transplantation, with a notably low incidence of cardiovascular events.
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Enfermedades Cardiovasculares , Trasplante de Páncreas , Humanos , Supervivencia de Injerto , Estudios Retrospectivos , Estudios Prospectivos , Páncreas , Enfermedades Cardiovasculares/etiologíaRESUMEN
SARS-CoV-2 infection (COVID-19) has had a significant impact on transplant activity in our country. Mortality and the risk of complications associated with COVID-19 in kidney transplant recipients (KT) were expected to be higher due to their immunosuppressed condition and the frequent associated comorbidities. Since the beginning of the pandemic in March 2020 we have rapidly improved our knowledge about the epidemiology, clinical features and management of COVID-19 post-transplant, resulting in a better prognosis for our patients. KT units have been able to adapt their programs to this new reality, normalizing both donation and transplantation activity in our country.This manuscript presents a proposal to update the general recommendations for the prevention and treatment of infection in this highly vulnerable population such as KT.
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Activated sludge from municipal wastewater treatment processes can be used directly for the production of biodegradable polyesters from the family of polyhydroxyalkanoates (PHAs). However, municipal activated sludge typically cannot accumulate PHAs to very high levels and often low yields of polymer produced on substrate are observed. In the present work, it was found that the presence of calcium promotes selective growth and enrichment of the PHA-storing biomass fraction and significantly improved both PHA contents and yields. Calcium addition resulted in PHA contents of 0.60 ± 0.03 gPHA/gVSS and average PHA yields on substrate of 0.49 ± 0.03 gCODPHA/gCODHAc compared to 0.35 ± 0.01 gPHA/gVSS and 0.19 ± 0.01 gCODPHA/gCODHAc without calcium addition. After 48 h, three times more PHA was produced compared to control experiments without calcium addition. Higher PHA content and selective biomass production is proposed to be a consequence of calcium dependent increased levels of passive acetate uptake. Such more efficient substrate uptake could be related to a formation of calcium acetate complexes. Findings lead to bioprocess methods to stimulate a short-term selective growth of PHA-storing microorganisms and this enables improvements to the techno-economic feasibility for municipal waste activated sludge to become a generic resource for industrial scale PHA production.
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Polihidroxialcanoatos , Purificación del Agua , Aguas del Alcantarillado/química , Biomasa , Calcio , Reactores BiológicosRESUMEN
The developments of mixed culture polyhydroxyalkanoate production has been directed to maximize the biomass PHA content with limited attention to polymer quality. Direct comparison of PHA accumulation literature is challenging, and even regularly contradicting in reported results, due to underlying differences that are not well expressed. A study was undertaken to systematically compare the commonly reported process conditions for PHA accumulation by full-scale municipal activated sludge. A biomass acclimation step combined with a pulse-wise feeding strategy resulted in maximum average PHA contents and product yields. pH control and active nitrification did not result in observable effects on the PHA productivity. Under these conditions a high molecular weight polymer (1536 ± 221 kDa) can be produced. Polymer extraction recoveries were influenced by the PHA molecular weight. A standard protocol for an activated sludge PHA accumulation test including downstream processing and standardized extraction has been developed and is available as supplementary material.
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Polihidroxialcanoatos , Aguas del Alcantarillado , Nitrificación , Biomasa , Peso Molecular , Reactores BiológicosRESUMEN
Municipal activated sludge can be used for polyhydroxyalkanoate (PHA) production, when supplied with volatile fatty acids. In this work, standardized PHA accumulation assays were performed with different activated sludge to determine (1) the maximum biomass PHA content, (2) the degree of enrichment (or volume-to-volume ratio of PHA-accumulating bacteria with respect to the total biomass), and (3) the average PHA content in the PHA-storing biomass fraction. The maximum attained biomass PHA content with different activated sludge ranged from 0.18 to 0.42 gPHA/gVSS, and the degree of enrichment ranged from 0.16 to 0.51 volume/volume. The average PHA content within the PHA-accumulating biomass fraction was relatively constant and independent of activated sludge source, with an average value of 0.58 ± 0.07 gPHA/gVSS. The degree of enrichment for PHA-accumulating bacteria was identified as the key factor to maximize PHA content when municipal activated sludge is directly used for PHA accumulation. Future optimization should focus on obtaining a higher degree of enrichment of PHA-accumulating biomass, either through selection during wastewater treatment or by selective growth during PHA accumulation. A PHA content in the order of 0.6 g PHA/g VSS is a realistic target to be achieved when using municipal activated sludge for PHA production.