1,720,959 research outputs found
Immobilization of Pseudomonas putida A (ATCC 12633) cells: A promising tool for effective degradation of quaternary ammonium compounds in industrial effluents
Get PDFPseudomonas putida A (ATCC 12633) were encapsulated in Ca-alginate and their ability to degrade the quaternary ammonium compounds (QACs) tetradecylbenzyldimethylammonium chloride (C14BDMA), hexadecylbenzyldimethylammonium chloride (C16BDMA) and benzalkonium chloride (BAC) (a mixture 1:1 of C14BDMA and C16BDMA), was tested and compared with the degradation of the same compounds by freely suspended cells. Degradation was carried out in pH 7.4 buffered medium, at 30 °C with agitation at 100 rpm. After 24 h of incubation immobilized cells degraded 90 % of 35 to 315 mg l-1 of C14BDMA, C16BDMA and BAC, whereas free cells were unable to degrade concentrations above 35 mg l-1. Immobilized cells of P. putida removed 80 % QACs of an industrial effluent in 48 h under both sterile and non-sterile conditions. Degradation of QACs carried out using the non-sterilized effluent showed that the beads could be reused up to four cycles without changing the degradation efficiency. The reduction in the QACs concentration after treatment with immobilized cells can be correlated with the reduction in the phytotoxicity to Lactuta sativa seed germination and root elongation. We conclude that immobilized QACs-degrading bacteria represent a promising tool for bioremediation of QACs in industrial wastewater systems.Fil: Bergero, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Lucchesi, Gloria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentin
Degradation of cationic surfactants using Pseudomonas putida A ATCC 12633 immobilized in calcium alginate beads
Get PDFIn this study, the degradation of tetradecyltrimethylammonium bromide (TTAB) by freely suspended and alginate-entrapped cells from the bacteria Pseudomonas putida (P. putida) A ATCC 12633 was investigated in batch cultures. The optimal conditions to prepare beads for achieving a higher TTAB degradation rate were investigated by changing the concentration of sodium alginate, pH, temperature, agitation rate and initial concentration of TTAB. The results show that the optimal embedding conditions of calcium alginate beads are 4 % w/v of sodium alginate content and 2 × 108 cfu ml−1 of P. putida A ATCC 12633 cells that had been previously grown in rich medium. The optimal degradation process was carried out in pH 7.4 buffered medium at 30 °C on a rotary shaker at 100 rpm. After 48 h of incubation, the free cells degraded 26 mg l−1 of TTAB from an initial concentration of 50 mg l−1 TTAB. When the initial TTAB concentration was increased to 100 mg l−1, the free cells lost their degrading activity and were no longer viable. In contrast, when the cells were immobilized on alginate, they degraded 75 % of the TTAB after 24 h of incubation from an initial concentration of 330 mg l−1 of TTAB. The immobilized cells can be stored at 4 °C for 25 days without loss of viability and can be reused without losing degrading capacity for three cycles.Fil: Bergero, Maria Fernanda. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lucchesi, Gloria Ines. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Degradation of cationic surfactants using immobilized bacteria: Its effect on adsorption to activated sludge
Get PDFAdsorption of cationic surfactants (QACs) Br-tetradecyltrimethylammonium (TTAB), Cl-tetradecylbenzyldimethylammonium (C14BDMA) and Cl-hexadecylbenzyldimethylammonium (C16BDMA) to activated sludge from a wastewater treatment plant was tested. Adsorption equilibrium was reached after 2 h, and for initial 200 mg L−1 81%, 90% and 98% of TTAB, C14BDMA and C16BDMA were respectively adsorbed. After six successive desorption cycles, 21% of TTAB and 12.7% of C14BDMA were desorbed from the sludge. In agreement with the percentage of QACs pre-adsorbed, the more hydrophobic the compound, the lesser the extent of desorption. Wastewater samples with activated sludge were supplemented with TTAB 200 mg L−1 and Ca-alginate beads containing the QACs-degrading microorganisms Pseudomonas putida A (ATCC 12633) and Aeromonas hydrophila MFB03. After 24 h, 10 mg L−1 of TTAB were detected in the liquid phase and 6–8 mg L−1 adsorbed to the sludge. Since without Ca-alginate beads or with empty beads total TTAB amount (phase solid and liquid) did not change, the 90% reduction of the initial 200 mg L−1 after treatment with immobilized cells was attributed to the bacterial consortium's capacity to biodegrade QACs. The results show the advantages of using immobilized bacteria to achieve complete QACs elimination from wastewater systems, thus preventing them from reaching the environment.Fil: Bergero, Maria Fernanda. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Lucchesi, Gloria Ines. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Immobilization of a microbial consortium on Ca-alginate enhances degradation of cationic surfactants in flasks and bioreactor
Get PDFFree cells and Ca-alginate encapsulated cells of Aeromonas hydrophila MFB03 removed in shake flasks up to 65% of tetradecyltrimethylammonium bromide (TTAB) 30 mg l−1. While planktonic cells were unable to utilize 50 mg l−1 benzalkonium chloride (BAC) after 48 h of incubation, the immobilized cells of A. hydrophila MFB03 removed up to 90% of BAC (25–210 mg l−1) in the same period. A microbial immobilized consortium formed by A. hydrophila MFB03 and Pseudomonas putida A (ATCC 12633) was able to degrade, after 24–30 h, 65% of TTAB and 100% of BAC, both added at 50 mg l−1. BAC was completely removed by the consortium encapsulated in a stirred tank bioreactor at 30 °C, 100 rpm and 0.024 g beads ml−1 of medium, after 12 h of incubation; reaching a degradation rate five times greater than the one obtained in shake flasks (0.415 vs. 0.089 mg−1 h−1, respectively). The system completely removed, with the same efficiency, 50 mg l−1 of BAC for 3 consecutive cycles. These results indicate that the use of Ca-alginate beads containing cells of the consortium can be considered a proper method to achieve degradation of cationic surfactants.Fil: Bergero, Maria Fernanda. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Liffourrena, Andres Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Opizzo Balza, Bianca. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; ArgentinaFil: Fochesatto, A.S.. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; ArgentinaFil: Lucchesi, Gloria Ines. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Practical class to evaluate the adsorption of Al(III) ions from aqueous solutions using non-viable bacterial biomass trapped in an agar-agar matrix
No full textThe contamination of wastewater with metals and the use of biotechnologies to remove them is commonly discussed in theoretical biology, microbiology and biotechnology classes aimed at undergraduate students. This work introduces an easy, economical and safe practical laboratory class related to this topic. The practice consists in performing batch assays to remove Al(III) from aqueous solutions by using non-viable bacterial biomass trapped in agar-agar beads. Students prepare these beads and analyse Al(III) adsorption on the basis of: pH, time of contact, and Al(III) concentration. Free Al(III) is quantified spectrophotometrically through a simple colorimetric method. The data obtained are used to calculate and graphically represent the amount of metal adsorbed to the beads. Finally, students analyse and discuss the results to determine the optimal adsorption conditions. Moreover, since Al(III) becomes much more attached to beads with trapped biomass than to beads without microorganisms, the class serves to demonstrate one of the advantages of using immobilised microbial cells in adsorption processes. This class was satisfactorily implemented in an upper-level course for undergraduate students of biological sciences. They were able to properly execute all the experiments and calculations proposed and to become acquainted with useful experimental design to remove a metal.Fil: Boeris, Paola Sabrina. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Biotecnologia Ambiental y Salud. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Biotecnologia Ambiental y Salud.; ArgentinaFil: Bergero, Maria Fernanda. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Biotecnologia Ambiental y Salud. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Biotecnologia Ambiental y Salud.; ArgentinaFil: Heredia, Romina Marisa. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Biotecnologia Ambiental y Salud. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Biotecnologia Ambiental y Salud.; ArgentinaFil: Liffourrena, Andres Sebastian. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Biotecnologia Ambiental y Salud. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Biotecnologia Ambiental y Salud.; ArgentinaFil: Lucchesi, Gloria Ines. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Biotecnologia Ambiental y Salud. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Biotecnologia Ambiental y Salud.; Argentin
Release of outer membrane vesicles in pseudomonas putida as a response to stress caused by cationic surfactants
Get PDFPseudomonas putida A (ATCC 12633), a degrader of cationic surfactants, releases outer membrane vesicles (OMVs) when grown with tetradecyltrimethylammonium bromide (TTAB) as the sole carbon, nitrogen and energy source. The OMVs exhibit a bilayer structure and were found to be composed of lipopolysaccharides, proteins and phospholipids (PLs) such as cardiolipin, phosphatidylcholine, phosphatidic acid and phosphatidylglycerol (PG). The OMVs showed a marked increase in the PG content, approximately 43 % higher than the amount registered in the parent cells from which the vesicles were derived. After growth of P. putida with TTAB, the amount of lipoprotein covalently cross-linked to the peptidoglycan showed a twofold decrease when compared with values found after growth without the surfactant [16±2 and 28±3 mg (mg cell envelope protein)-1, respectively]. This decrease in the amount of lipoprotein can be related to areas of loss of contact between the outer membrane and the peptidoglycan and, therefore, to OMV production. In addition, due to its amphiphilic nature, TTAB can contribute to OMV biogenesis, through a physical mechanism, by induction of the curvature of the membrane. Taking into account that OVMs were produced when the cells were grown under external stress, caused by the surfactant, and that TTAB was detected in the vesicles [48 nmol TTAB (nmol PL)-1], we concluded that this system of TTAB elimination is a mechanism that P. putida A (ATCC 12633) would utilize for alleviating stress caused by cationic surfactants.Fil: Heredia, Romina Marisa. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Boeris, Paola Sabrina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Liffourrena, Andres Sebastian. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Bergero, Maria Fernanda. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: López, Gastón Alberto. Universidad Nacional de Río Cuarto; ArgentinaFil: Lucchesi, Gloria Ines. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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