RESUMO
The treatment of dairy wastewater in methanogenic reactors cause several problems due to their high lipid content. One strategy to overcome these problems is the use of commercial formulations. Here we studied the effect of adding a commercial formulation, designed to improve fat degradation, on both the microbial community composition and reactor performance. Samples from two full-scale Up-flow Anaerobic Sludge Blanket (UASB) reactors in parallel arrangement were analysed. The commercial product was added to one of the reactors while the other was used as control. The amendment increased significantly the fat removal but an accumulation of volatile fatty acids was detected. Nevertheless, no significant differences were observed in the total Chemical Oxygen Demand (COD) removal and biogas production between reactors. A significant change in the bacterial community was not detected by 16S rRNA gene Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis probably due to the limitation of the technique. A strong change in the composition of the phylum Firmicutes was detected with 16S rRNA gene amplicon sequencing; however, it didn't persist during the whole operation period. The relative abundance of minor Operational Taxonomic Units (OTUs) with sequences related to syntrophic bacteria increased with the amendment. Although a better hydrolytic capacity was obtained when adding the commercial product, the overall process did not improve and no increase in biogas production was detected. Alternative strategies could be applied to avoid the accumulation of intermediary products and improve biogas production as intermittent addition of the commercial product or batch operation of reactors.
Assuntos
Euryarchaeota , Esgotos , Anaerobiose , Biocombustíveis , Reatores Biológicos , Metano , RNA Ribossômico 16SRESUMO
Pseudomonas aeruginosa is considered an opportunistic pathogen, causing a wide variety of infections in compromised hosts, also frequently develops multi-resistance to antibiotics and can colonize various habitats, including water systems. The main aim of this study was to investigate antibiotics susceptibility pattern, genotypic diversity and detection of resistence genes in P. aeruginosa isolates from clinical and aquatic environment sources. Of the 220 P. aeruginosa isolates examined, 48 were clinical isolates and 172 isolates from wastewater and freshwater. Susceptibility to eight antimicrobial agents was carried out by disk diffusion method. Clinical and environmental isolates were screened for the presence of the genes encoding blaKPC-2, blaCTX-M-9, blaPER-1, blaOXA-10, blaIMP-1, blaVIM-2 and blaampC by polymerase chain reaction (PCR). Isolates were examined with PCR-SSCP analysis of partial DNAr 16S sequence. Isolates were mainly resistant to cefoxitin. Multidrug-resistant P. aeruginosa (MDRPA) strains were found in 70% and 90.3% of the clinical and environmental isolates, respectively. The prevalence rates of â-lactamase genes were recorded (blaKPC-2 41.3%, blaVIM-2 36.8%, blaIMP-1 13.6%, blaCTX-M-9 10.9% and blaampC 10.5%,). The PCR-SSCP analysis showed three conformational patterns. All clinical isolates and most environmental isolates were grouped into a single cluster. In this study, we found that P. aeruginosa strains recovered from city water systems must be considered potential reservoir for ESBL genes, especially blaKPC-2 and blaVIM-2.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Pseudomonas aeruginosa/efeitos dos fármacos , Colômbia , Água Doce/microbiologia , Genes Bacterianos , Genótipo , Humanos , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/genética , Águas Residuárias/microbiologia , Abastecimento de ÁguaRESUMO
AIMS: The phylum Chloroflexi is frequently found in high abundance in methanogenic reactors, but their role is still unclear as most of them remain uncultured and understudied. Hence, a detailed analysis was performed in samples from five up-flow anaerobic sludge blanket (UASB) full-scale reactors fed different industrial wastewaters. METHODS AND RESULTS: Quantitative PCR show that the phylum Chloroflexi was abundant in all UASB methanogenic reactors, with higher abundance in the reactors operated for a long period of time, which presented granular biomass. Both terminal restriction fragment length polymorphism and 16S rRNA gene amplicon sequencing revealed diverse Chloroflexi populations apparently determined by the different inocula. According to the phylogenetic analysis, the sequences from the dominant Chloroflexi were positioned in branches where no sequences of the cultured representative strains were placed. Fluorescent in situ hybridization analysis performed in two of the reactors showed filamentous morphology of the hybridizing cells. CONCLUSIONS: While members of the Anaerolineae class within phylum Chloroflexi were predominant, their diversity is still poorly described in anaerobic reactors. Due to their filamentous morphology, Chloroflexi may have a key role in the granulation in methanogenic UASB reactors. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results bring new insights about the diversity, stability, dynamics and abundance of this phylum in full-scale UASB reactors which aid in understanding their function within the reactor biomass. However, new methodological approaches and analysis of bulking biomass are needed to completely unravel their role in these reactors. Combining all this knowledge with reactor operational parameters will allow to understand their participation in granulation and bulking episodes and design strategies to prevent Chloroflexi overgrowth.
Assuntos
Reatores Biológicos/microbiologia , Chloroflexi/isolamento & purificação , Biomassa , Chloroflexi/classificação , Chloroflexi/citologia , Chloroflexi/genética , Hibridização in Situ Fluorescente , Metano/metabolismo , Filogenia , Esgotos/microbiologia , Águas Residuárias/microbiologiaRESUMO
An important pollutant produced during the cheese making process is cheese whey which is a liquid by-product with high content of organic matter, composed mainly by lactose and proteins. Hydrogen can be produced from cheese whey by dark fermentation but, organic matter is not completely removed producing an effluent rich in volatile fatty acids. Here we demonstrate that this effluent can be further used to produce energy in microbial fuel cells. Moreover, current production was not feasible when using raw cheese whey directly to feed the microbial fuel cell. A maximal power density of 439 mW/m2 was obtained from the reactor effluent which was 1000 times more than when using raw cheese whey as substrate. 16S rRNA gene amplicon sequencing showed that potential electroactive populations (Geobacter, Pseudomonas and Thauera) were enriched on anodes of MFCs fed with reactor effluent while fermentative populations (Clostridium and Lactobacillus) were predominant on the MFC anode fed directly with raw cheese whey. This result was further demonstrated using culture techniques. A total of 45 strains were isolated belonging to 10 different genera including known electrogenic populations like Geobacter (in MFC with reactor effluent) and known fermentative populations like Lactobacillus (in MFC with cheese whey). Our results show that microbial fuel cells are an attractive technology to gain extra energy from cheese whey as a second stage process during raw cheese whey treatment by dark fermentation process.
Assuntos
Queijo , Fontes de Energia Bioelétrica , RNA Ribossômico 16S , Soro do Leite , Proteínas do Soro do LeiteRESUMO
Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the (210)Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90 s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90 s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90 s, which dismissed catchment erosion and pollution.
Assuntos
Ecossistema , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Metais Pesados/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/análise , Cuba , Radioisótopos de Chumbo/análise , Fatores de Tempo , Poluição Química da Água/prevenção & controleRESUMO
Wastewater from dairy industries, characterized by its high COD content and relative high COD/TKN ratio, requires post-treatment after anaerobic treatment to complete the removal of organic matter and nutrients. Due to its simplicity, robustness and low maintenance costs, sequencing batch reactors (SBR) result in an attractive system, especially in case of small dairy industries in order to comply with the emission standards. The goal of this work was to determine the operational parameters, optimize the performance, and study the stability of the microbial population of a SBR system for the post-treatment of an anaerobic pond effluent. High and stable removal of COD and TKN was achieved in the reactor, which can easily be set up in dairy industries. An active nitrifying population was selected during reactor operation and maintained relatively stable, while the heterotrophic (total and denitrifying) communities were more unstable and susceptible to changes in the operating conditions.
Assuntos
Indústria de Laticínios , Microbiologia da Água , Poluentes da Água , Anaerobiose , Archaea/metabolismo , Bactérias/metabolismo , Hibridização in Situ FluorescenteRESUMO
Slaughterhouse wastewater is a complex effluent with an important content of organic nitrogen. After an anaerobic treatment where most of the organic matter is removed, the nitrogen, remains as ammonium and post-treatment of the effluent is necessary. Sequencing batch reactor (SBR) technology has been developed to completely remove nitrogen in one single reactor combining aerobic and anoxic stages. Under oxygen limited conditions only nitrite is produced with concomitant energy saving. The stability and diversity of the microbial community from a nitrifying denitrifying SBR operated under oxygen limited conditions were studied using molecular and respirometric methods. The AOB (ammonia oxidizing bacteria) community was relatively stable Nitrosomonas being the dominant genera although Nitrosospira and Nitrosococcus were detected in low proportions. Nitrite oxidizing bacteria were out competed during the operation under oxygen-limited conditions. After an increase of the DO in the reactor Nitrobacter spp were detected suggesting that they remained in the system. Changes in the AOB and denitrifying communities were observed after the DO increase. Sedimentation problems were detected during operation, this could be related to the predominance of Thauera spp detected by FISH and T-RFLP.
Assuntos
Matadouros , Recuperação e Remediação Ambiental/métodos , Oxigênio/química , Microbiologia da Água , Hibridização in Situ Fluorescente , Polimorfismo de Fragmento de RestriçãoRESUMO
Objetivo: Determinar la realidad psicosocial de la población infanto juvenil perteneciente a la educación municipalizada de la ciudad de Calama. Material y Método: Se estudió una muestra representativa de la población de séptimo básico a cuarto medio de la educación municipalizada de la ciudad de Calama (n = 1 069, 543 hombres y 526 mujeres). Los instrumentos utilizados fueron: Cuestionario de factores protectores y de riesgo en salud mental para adolescentes entre 11 y 18 años de edad, Cuestionario psicopatológico para adolescentes, Cuestionario de Depresión Infantil (CDI) y Cuestionario de ideación e intento de suicidio. Resultados: Los factores de riesgo predominantes son: falta de destrezas sociales y pertenencia a grupo, bajo autoconcepto/autoestima y situación familiar irregular. Los factores protectores más frecuentes son: expectativas futuras, ausencia de conductas de riesgo social, de alcohol y drogas y sexuales, y ausencia de maltrato. El 36,6 por ciento de las mujeres consultadas, es decir 191 casos, alcanzan puntajes iguales o mayores al corte respectivo en el Cuestionario Psicopatológico para adolescentes versus el 22,2 por ciento de los hombres consultados (121 casos). Los factores de riesgo predominantes en el grupo con psicopatología son las variables ausencia de pertenencia a grupo y bajo autoconcepto/autoestima. La ideación suicida va entre el 6,4 por ciento al 14,6 por ciento de acuerdo a como se postule la pregunta. El 18 por ciento de los entrevistados había cometido un o más intento de suicidio. Los 247 sujetos con ideación suicida declarada presentan puntajes igual o superior al corte respectivo en el CDI. Además, todos los sujetos que declaran tener uno o más intentos de suicidio (n = 192) presentan puntajes superiores o iguales al corte respectivo en el CDI. Conclusión: Tempranamente la familia y posteriormente la institución educacional en este grupo etario estudiado puede llegar a ser un medio de intervención para fomentar factores protectores o disminuir factores de riesgo de éstos jóvenes.
Assuntos
Humanos , Adolescente , Criança , Psicologia do Adolescente , Psicologia da Criança , Psicologia Social/métodos , Epidemiologia Descritiva , Saúde Mental , Fatores de Proteção , Fatores de RiscoRESUMO
The microbial community in two acetate-fed denitrifying reactors, inoculated with methanogenic sludge, was monitored by 16S rDNA-based methods (SSCP and FISH). Both reactors converged to similar, stable communities. The predominant organisms belonged to the genera Thauera, Paracoccus and Denitrobacter, detected both by molecular and culture-based methods.
Assuntos
Bactérias/genética , Reatores Biológicos , Esgotos/microbiologia , DNA Bacteriano , Hibridização in Situ Fluorescente , Metano/metabolismo , Polimorfismo Conformacional de Fita Simples , Dinâmica Populacional , RNA Ribossômico 16S/análiseRESUMO
Aerobic and methanogenic consortia were evaluated as inocula for laboratory scale denitrifying reactors, fed with a synthetic wastewater with acetate as the main electron donor. The denitrifying microflora of inocula and reactors was evaluated by specific denitrifying activity, enumeration and isolation of denitrifiers, which were screened by amplified ribosomal DNA restriction analysis. Reactor performance was monitored by COD and nitrate removal efficiencies and granule size. The aerobic sludge failed to form granules, probably due to the development of a filamentous, nitrate-reducing organism which was characterised by 16SrDNA sequencing as Bacillus cereus. The methanogenic sludge showed denitrifying activity and adapted very rapidly to denitrifying conditions in the two reactors seeded with granules of different sizes. Denitrifiers grew around the granules, increasing the specific denitrifying activity of the sludge over 10-fold. Exopolymer-forming organisms, belonging to the same species, were isolated from both reactors. Granule size increased during operation, but flotation of the aggregates, related to gas retention was observed.