RESUMO
In this study, native ureolytic bacteria were isolated from copper tailings soils to perform microbial-induced carbonate precipitation (MICP) tests and evaluate their potential for biocement formation and their contribution to reduce the dispersion of particulate matter into the environment from tailings containing potentially toxic elements. It was possible to isolate a total of 46 bacteria; among them only three showed ureolytic activity: Priestia megaterium T130-1, Paenibacillus sp. T130-13 and Staphylococcus sp. T130-14. Biocement cores were made by mixing tailings with the isolated bacteria in presence of urea, resulting similar to those obtained with Sporosarcina pasteurii and Bacillus subtilis used as positive control. Indeed, XRD analysis conducted on biocement showed the presence of microcline (B. subtilis 17%; P. megaterium 11. 9%), clinochlore (S. pasteurii, 6.9%) and magnesiumhornblende (Paenibacillus sp. 17.8%; P. megaterium 14.6%); all these compounds were not initially present in the tailings soils. Moreover the presence of calcite (control 0.828%; Paenibacillus sp. 5.4%) and hematite (control 0.989%; B. subtilis 6.4%) was also significant unlike the untreated control. The development of biofilms containing abundant amount of Ca, C, and O on microscopic soil particles was evidenced by means of FE-SEM-EDX and XRD. Wind tunnel tests were carried out to investigate the resistance of biocement samples, accounted for a mass loss five holds lower than the control, i.e., the rate of wind erosion in the control corresponded to 82 g/m2h while for the biocement treated with Paenibacillus sp. it corresponded to only 16.371 g/m2h. Finally, in compression tests, the biocement samples prepared with P. megaterium (28.578 psi) and Paenibacillus sp. (28.404 psi) showed values similar to those obtained with S. pasteurii (27.102 psi), but significantly higher if compared to the control (15.427 psi), thus improving the compression resistance capacity of the samples by 85.2% and 84.1% with respect to the control. According to the results obtained, the biocement samples generated with the native strains showed improvements in the mechanical properties of the soil supporting them as potential candidates in applications for the stabilization of mining liabilities in open environments using bioaugmentation strategies with native strains isolated from the same mine tailing.
RESUMO
Magnetic fields in biological systems is a promising research field; however, their application for microalgae has not been fully exploited. This work aims to measure the enzymatic activity and non-enzymatic activity of two microalgae species in terms of superoxide dismutase (SOD), catalase (CAT), and carotenoids, respectively, in response to static magnetic fields-induced stress. Two magnet configurations (north and south) and two exposure modes (continuous and pulse) were applied. Two microalgae species were considered, the Scenedesmus obliquus and Nannochloropsis gaditana. The SOD activity increased by up to 60% in S. obliquus under continuous exposure. This trend was also found for CAT in the continuous mode. Conversely, under the pulse mode, its response was hampered as the SOD and CAT were reduced. For N. gaditana, SOD increased by up to 62% with the south configuration under continuous exposure. In terms of CAT, there was a higher activity of up to 19%. Under the pulsed exposure, SOD activity was up to 115%. The CAT in this microalga was increased by up to 29%. For N. gaditana, a significant increase of over 40% in violaxanthin production was obtained compared to the control, when the microalgae were exposed to SMF as a pulse. Depending on the exposure mode and species, this methodology can be used to produce oxidative stress and obtain an inhibitory or enhanced response in addition to the significant increase in the production of antioxidant pigments.
Assuntos
Microalgas , Animais , Campos Magnéticos , Estresse OxidativoRESUMO
Due to the effects of Hurricane Patricia (2015), the bulk freighter "El Llanitos" ran aground in the rocky intertidal zone of Colima, Mexico. We assessed the impact of this ship's stranding on a population of the gastropod Plicopurpura pansa. Toxic elements, hydrocarbons, shell deformities, presence of tumors, imposex, and morphological relationships were analyzed. Two years after the stranding occurred, high cyanide concentrations (0.0363 mg/l) and Ni concentrations above permissible limits (3.35 mg/l) were found in surface seawater. Hydrocarbon concentrations were high in the aft zone of the ship and decreased towards the bow area of the freighter. The P. pansa specimens collected closest to the ship structure presented a high prevalence of tumorations in the structure of the foot and morphological anomalies in the shell structure; imposex was 32% and there was evidence of effects on the growth indicator. The evidence presented here supports the existence of a significant impact from the grounding of the ship on a protected gastropod species associated with the rocky intertidal zone on the coast of Colima. The potential of P. pansa as a bioindicator species of pollution caused by toxic elements and hydrocarbons associated with stranding events in the tropical Pacific is documented.
Assuntos
Tempestades Ciclônicas , Gastrópodes , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental , México , Água do Mar , NaviosRESUMO
In this study, we designed and evaluated a microalgal pretreatment method using cellulolytic bacteria that naturally degrades microalgae in their native habitat. Bacterial strains were isolated from each of two mollusk species in a medium containing 1% carboxymethyl cellulose agar. We selected nine bacterial strains that had endoglucanase activity: five strains from Mytilus chilensis, a Chilean mussel, and four strains from Mesodesma donacium, a clam found in the Southern Pacific. These strains were identified phylogenetically as belonging to the genera Aeromonas, Pseudomonas, Chryseobacterium, and Raoultella. The cellulase-producing capacities of these strains were characterized, and the degradation of cell walls in Botryococcus braunii and Nannochloropsis gaditana was tested with "whole-cell" cellulolytic experiments. Aeromonas bivalvium MA2, Raoultella ornithinolytica MA5, and Aeromonas salmonicida MC25 degraded B. braunii, and R. ornithinolytica MC3 and MA5 degraded N. gaditana. In addition, N. gaditana was pretreated with R. ornithinolytica strains MC3 and MA5 and was then subjected to an anaerobic digestion process, which increased the yield of methane by 140.32% and 158.68%, respectively, over that from nonpretreated microalgae. Therefore, a "whole-cell" cellulolytic pretreatment can increase the performance and efficiency of biogas production.
Assuntos
Biocombustíveis , Microalgas/metabolismo , Microalgas/microbiologia , Aeromonas/classificação , Aeromonas/enzimologia , Aeromonas/isolamento & purificação , Biodegradação Ambiental , Celulase/metabolismo , Celulose/metabolismo , Clorófitas/metabolismo , Clorófitas/microbiologia , Chryseobacterium/classificação , Chryseobacterium/enzimologia , Chryseobacterium/isolamento & purificação , DNA Bacteriano/genética , Enterobacteriaceae/classificação , Enterobacteriaceae/enzimologia , Enterobacteriaceae/isolamento & purificação , Metano/metabolismo , Filogenia , Pseudomonas/classificação , Pseudomonas/enzimologia , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genéticaRESUMO
This study reports molecular markers potentially associated with resistance or sensitivity to the impact of copper in juvenile red abalone, Haliotis rufescens, in the north of Chile under experimental conditions. Genomic analysis was made applying subtractive hybridization libraries (SSH) to identify genes up-and down regulated during cooper exposure in abalone over periods of 12 and 168 h exposed to 2.5 and 10 µg/L of Cu(+2). Results obtained from the SSH library revealed 368 different sequences regulated by copper, that correspond to eight major physiological functions. The validation of these sequences obtained by SSH as well as their expression kinetics were made by PCR in real time on 14 potential genes regulated by metal stress. This study provides information for the characterization of potential genomic markers that may be used in future environmental monitoring and to investigate new mechanisms of stress to copper in this commercially important marine species.
Assuntos
Cobre/metabolismo , Etiquetas de Sequências Expressas , Gastrópodes/efeitos dos fármacos , Gastrópodes/genética , Poluentes Químicos da Água/metabolismo , Animais , Chile , Cobre/toxicidade , Monitoramento Ambiental , Regulação da Expressão Gênica , Dados de Sequência Molecular , Análise de Sequência de DNA/veterinária , Poluentes Químicos da Água/toxicidadeRESUMO
Para estudiar la efectividad y seguridad de la anticoagulación en la fibrilación auricular no valvular crónica en pacientes menores de 75 años de la práctica clínica diaria incluimos en un estudio prospectivo 345 pacientes consecutivos atendidos entre el 1 de febrero de 2000 y el 1 de febrero de 2002 en dos consultas de cardiología. Se les indicó tratamiento anticoagulante de acuerdo con las recomendaciones de las sociedades científicas y fueron seguidos para evaluar eventos mayores (muerte, ictus, accidente isquémico transitorio, embolismos periféricos o hemorragia grave) por grupo de tratamiento. Los pacientes con terapia anticoagulante (n = 262,76%) presentaron una mayor frecuencia de hipertensión y embolismo previo y un mayor número de factores de riesgo cardioembólicos (p < 0.001); el 92% de los pacientes tratados sin anticoagulantes recibieron antiagregantes. Tras 23 ± 13 meses de seguimiento, la tasa (por 100 pacientes-año) de eventos embólicos (0.82 versus3.42, p = 0.022) fue menor en los pacientes que recibieron anticoagulantes, sin diferencias significativas en las tasas de sangrado grave (0.61 frente a 1.37, p = 0.39), ni en la mortalidad total (1.23 frente a 1.37, p = 0.96). La anticoagulación oral en la fibrilación auricular no valvular de aucerdo con las recomendaciones de las sociedades científicas es efectiva y segura en pacientes menores de 75 años en la práctica clínica diaria.
Our objective was to study the effectiveness and safety of oral anticoagulation for permanent non-valvular atrial fibrillation in patients younger than 75 years seen in dailyclinical practice. In a prospective study, we included 345 consecutive patients seen since February, 1st 2000 toFebruary 1st 2002 in two outpatient cardiology clinics. Anticoagulant treatment was indicated following scientific societies recommendations; and patients were divided intreatment groups and followed for major events (death,stroke, transient ischemic attack, peripheral embolism orsevere haemorrhage). Anticoagulated patients (n = 262,76%) presented hypertension and previous embolism more frequently; as well as a greater number of cardioembolicrisk factors (p < 0.001). Ninety-two percent ofnon-anticoagulated patients received platelet aggregation inhibitors. After 23 ± 13 months of follow-up, the rateof embolic events (per 100 patients-year) was lower inanticoagulated patients (0.82 versus 3.42, p = 0.022). Rates of severe bleeding (0.61 versus 1.37, p = 0.39) andall-cause mortality (1.23 versus 1.37, p = 0.96) showed no significant differences. Oral anticoagulation in nonvalvularatrial fibrillation following the recommendationsof scientific societies is effective and safe in patients younger than 75 years in daily clinical practice.
Assuntos
Anticoagulantes , Fibrilação Atrial , Acidente Vascular Cerebral , Hematologia , Hipertensão , TromboemboliaRESUMO
Marine biofouling is a present and potentially increasing future problem at molluscan culture centres. The problem is highly variable, exists on different scales, and its negative impact on cultured organisms and related economic losses at these centres has not been significantly controlled. One approach to fouling control has been the incorporation of natural substances into anti-fouling paints which inhibit the settlement of common fouling organisms. The main objective of the present study was the isolation of naturally occurring substances from marine bacteria which were inhibitory to the settlement of Ciona intestinalis and Pyura praeputialis, two tunicate species causing serious fouling problems in scallop culture systems in Chile. Numerous bacterial strains were isolated from microfouling on natural and artificial substrates submerged in the sea; of 73 strains isolated, 20 percent demonstrated inhibitory effects on the settlement of the larvae of the above cited tunicates. The inhibitory substances produced by the active bacteria were extracellular, and could be incorporated in an inert matrix (PhytagelTM) without losing their inhibitory properties. Some properties of the inhibitory substance isolated from bacterial strain Clon Nil-LEM (Alteromonas sp) included thermostability, MW < 3500 Da, peptidase lability (against C. intestinalis), and undiminished inhibitory activity when incorporated in the inert matrix.