7 research outputs found
Pedagogic Content Knowledge (PCK) in university Biotechnology teaching. The microbial specific growth rate (μ) case
En este trabajo se presenta un análisis de las ideas relacionadas al concepto de velocidad específica de
crecimiento microbiano (μ) que presentaron estudiantes universitarios que cursaban la orientación en
biotecnología del último año de la carrera de Bioquímica (Facultad de Farmacia y Bioquímica, Universidad de
Buenos Aires, Argentina). El estudio se realizó en base a las respuestas que dieron los estudiantes, de manera
anónima, frente a la solicitud espontanea de que explicaran qué entendían por μ. El análisis se focalizó en la
identificación de los factores que podrían relacionarse con las ideas que mostraron los estudiantes, entre las que
se incluye el tratamiento previo del concepto, la tendencia a la reducción funcional, el pragmatismo y la
posibilidad de que se trate de concepciones alternativas pero en un campo muy específico y aplicado de las
ciencias como es la biotecnología. Se plantean estrategias aplicadas para la reconstrucción del concepto de μ
considerando estos factores. Las experiencias y conclusiones que surgen de este trabajo pretenden contribuir al
desarrollo del Conocimiento Didáctico del Contenido (CDC) para ciencias aplicadas en general, y para la
biotecnología en particular.In this work, a study based on the university student’s conception about microbial specific growth rate (μ) is
presented. The study was focused on last year students of the Biochemist career (Buenos Aires University,
Argentina). It was developed considering the answers given anonymously by the students when they were
spontaneously asked about the meaning of μ. The analysis was focused in the identification of factors which
could be related with the students´ ideas about μ, such as the previous work with the subject, the tendency to the
functional reduction, the pragmatisms and the possibility of alternative conceptions, but related with a specific
field of applied sciences, such as biotechnology. Strategies aiming to the reconstruction of the μ concept were
proposed considering these factors. The experiences presented in this work will contribute to the development of
the Pedagogical Content Knowledge (PCK) in applied sciences, particularly in biotechnology
Conocimiento Didáctico del Contenido (CDC) en la enseñanza universitaria de Biotecnología. El caso de la velocidad específica de crecimiento microbiano (μ).
En este trabajo se presenta un análisis de las ideas relacionadas al concepto de velocidad específica de crecimiento microbiano (μ) que presentaron estudiantes universitarios que cursaban la orientación en biotecnología del último año de la carrera de Bioquímica (Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina). El estudio se realizó en base a las respuestas que dieron los estudiantes, de manera anónima, frente a la solicitud espontanea de que explicaran qué entendían por μ. El análisis se focalizó en la identificación de los factores que podrían relacionarse con las ideas que mostraron los estudiantes, entre las que se incluye el tratamiento previo del concepto, la tendencia a la reducción funcional, el pragmatismo y la posibilidad de que se trate de concepciones alternativas pero en un campo muy específico y aplicado de las ciencias como es la biotecnología. Se plantean estrategias aplicadas para la reconstrucción del concepto de μ considerando estos factores. Las experiencias y conclusiones que surgen de este trabajo pretenden contribuir al desarrollo del Conocimiento Didáctico del Contenido (CDC) para ciencias aplicadas en general, y para la biotecnología en particular.Palabras clave: conceptos específicos; biotecnología; velocidad específica de crecimiento; conocimiento didáctico del contenido.Pedagogic Content Knowledge (PCK) in university Biotechnology teaching. The microbial specific growth rate (μ) caseIn this work, a study based on the university student’s conception about microbial specific growth rate (μ) is presented. The study was focused on last year students of the Biochemist career (Buenos Aires University, Argentina). It was developed considering the answers given anonymously by the students when they were spontaneously asked about the meaning of μ. The analysis was focused in the identification of factors which could be related with the students´ ideas about μ, such as the previous work with the subject, the tendency to the functional reduction, the pragmatisms and the possibility of alternative conceptions, but related with a specific field of applied sciences, such as biotechnology. Strategies aiming to the reconstruction of the μ concept were proposed considering these factors. The experiences presented in this work will contribute to the development of the Pedagogical Content Knowledge (PCK) in applied sciences, particularly in biotechnology.Keywords: specific concepts; biotechnology; specific growth rate; pedagogical knowledge content
Pedagogic Content Knowledge (PCK) in university Biotechnology teaching. The microbial specific growth rate (μ) case
En este trabajo se presenta un análisis de las ideas relacionadas al concepto de velocidad específica de crecimiento microbiano (μ) que presentaron estudiantes universitarios que cursaban la orientación en biotecnología del último año de la carrera de Bioquímica (Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina). El estudio se realizó en base a las respuestas que dieron los estudiantes, de manera anónima, frente a la solicitud espontanea de que explicaran qué entendían por μ. El análisis se focalizó en la identificación de los factores que podrían relacionarse con las ideas que mostraron los estudiantes, entre las que se el tratamiento previo del concepto, la tendencia a la reducción funcional, el pragmatismo y la posibilidad de que se trate de concepciones alternativas pero en un campo muy específico y aplicado de las ciencias como es la biotecnología. Se plantean estrategias aplicadas para la reconstrucción del concepto de μ considerando estos factores. Las experiencias y conclusiones que surgen de este trabajo pretenden contribuir al desarrollo del conocimiento didáctico del contenido (CDC) en ciencias aplicadas en general, y para la biotecnología en particular.In this work, a study based on the university student’s conception about microbial specific growth rate (μ) is presented. The study was focused on last year students of the Biochemist career (Buenos Aires University, Argentina). It was developed considering the answers given anonymously by the students when they were spontaneously asked about the meaning of μ. The analysis was focused in the identification of factors which could be related with the students´ ideas about μ, such as the previous work with the subject, the tendency to the functional reduction, the pragmatisms and the possibility of alternative conceptions, but related with a specific field of applied sciences, such as biotechnology. Strategies aiming to the reconstruction of the μ concept were proposed considering these factors. The experiences presented in this work will contribute to the development of the Pedagogical Content Knowledge (PCK) in applied sciences, particularly in biotechnology.Fil: Ruberto, Lucas Adolfo Mauro. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Mac Cormack, Walter P.. Universidad de Buenos Aires; ArgentinaFil: Calabró López, Roberto Ariel. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Rodriguez Talou, Julian. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin
Down-scale of hydrodynamic shear effects on suspended cells
Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The effect of shear forces on suspended cells is one of the most complex problems in the scale-up of cell cultures. In the present paper, recent advances in the understanding of power consumption during agitation of Erlenmeyer flasks in rotary shakers are applied to direct comparison of the effects of shear forces on suspension cultures of Rubia tinctorum cells in a standard bioreactor and in shake flask cultures. The criterion selected as indicative of the shear stress acting on the cells was the critical eddy length, l, following Kolmogoroff's theory of isotropic turbulence. Standard flasks and four-baffled shake flasks were used. The effect of shear stress and light irradiation on cell viability, biomass, and anthraquinones (AQs) production was evaluated. The biomass concentration and AQs production obtained using baffled shake flasks agitated at 360 rpm were similar to that achieved previously in R. tinctorum suspension cultures growing in a stirred tank bioreactor operating at 450 rpm. It can be concluded that this down-scaled and simple flask culture system is a suitable and valid small scale instrument to study intracellular mechanisms of shear stress-induced AQs production in R. tinctorum suspension cultures, including intracellular phenomena, and can be eventually extended to other systems.dc201
Anthraquinones production in Rubia tinctorum cell suspension cultures: Down scale of shear effects
The effect of turbulence on suspended cells is one of the most complex problems in the scale-up of cell cultures. In the present paper, a direct comparison of the effects of turbulence on suspension cultures of Rubia tinctorum in a standard bioreactor and in shake flask cultures was done. A procedure derived from the well known global method proposed by Nishikawa et al. (1977) was applied. Standard flasks and four-baffled shake flasks were used. The effect of turbulence and light irradiation on cell viability, biomass, and anthraquinones (AQs) production was evaluated. The biomass concentration and AQs production obtained using baffled shake flasks agitated at 360 rpm were similar to that achieved in R. tinctorum suspension cultures growing in a stirred tank bioreactor operating at 450 rpm, previously published (Busto et al., 2008). The effect of light on AQs production was found to be very significant, and a difference of up to 48% was found in cells with and without illumination after 7 days of culture. It is concluded that this down-scaled and simple flask culture system is a suitable and valid small scale instrument for the study of intracellular mechanisms of turbulence-induced AQs production in R. tinctorum suspension cultures.Fil: Busto, Víctor Daniel. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Biotecnología; Argentina;Fil: Calabró López, Roberto Ariel. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Biotecnología; Argentina;Fil: Rodriguez Talou, Julian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Biotecnología; Argentina;Fil: Giulietti, Ana Maria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; Argentina;Fil: Merchuk, José C.. Ben Gurion University of The Negev; Israel; Jerusalem College of Engineering. Department of Pharmaceutical Engineering; Israel
Hydrocarbon removal and bacterial community structure in on-site biostimulated biopile systems designed for bioremediation of diesel-contaminated Antarctic soil
Several studies have shown that biostimulation can promote hydrocarbon bioremediation processes in Antarctic soils. However, the effect of the different nutrient sources on hydrocarbon removal heavily depends on the nutrients used and the soil characteristics. In this work, using a sample of chronically contaminated Antarctic soil that was exposed to a fresh hydrocarbon contamination, we analyzed how a complex organic nutrient source such as fish meal (FM) and a commercial fertilizer (OSEII) can affect hydrocarbon biodegradation and bacterial community composition. Both amended and unamended (control) biopiles were constructed and controlled at Carlini Station and sampled at days 0, 5, 16, 30 and 50 for microbiological, chemical and molecular analyses. FM caused a fast increase in both total heterotrophic and hydrocarbon degrading bacterial counts. These high values were maintained until the end of the assay, when statistically significant total hydrocarbon removal (71 %) was detected when compared with a control system. The FM biopile evidenced the dominance of members of the phylum Proteobacteria and a clear shift in bacterial structure at the final stage of the assay, when an increase of Actinobacteria was observed. The biopile containing the commercial fertilizer evidenced a hydrocarbon removal activity that was not statistically significant when compared with the untreated system and exhibited a bacterial community that differed from those observed in the unamended and FM-amended biopiles. In summary, biostimulation using FM in biopiles significantly enhanced the natural hydrocarbon-degradation activity of the Carlini station soils in biopile systems and caused significant changes in the bacterial community structure. The results will be considered for the future design of soil bioremediation protocols for Carlini Station and could also be taken into account to deal with diesel-contaminated soils from other cold-climate areas.Fil: Dias, Romina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Ruberto, Lucas Adolfo Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Virología; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Calabró López, Roberto Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Virología; ArgentinaFil: Lo Balbo, Alfredo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: del Panno, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Mac Cormack, Walter Patricio. Universidad de Buenos Aires; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin