Papers by Miguel A Galvagno
Letters in Applied Microbiology, 2012
To maximize biomass production of an ochratoxigenic mould-controlling strain of Lachancea therm... more To maximize biomass production of an ochratoxigenic mould-controlling strain of Lachancea thermotolerans employing response surface methodology (RSM). Using Plackett-Burman screening designs (PBSD) and central composite designs (CCD), an optimized culture medium containing (g l(-1) ): fermentable sugars (FS), 139·2, provided by sugar cane molasses (CMz), (NH(4) )(2) HPO(4) (DAP), 9·0, and yeast extract (YE), 2·5, was formulated. Maximal cell concentration obtained after 24 h at 28°C was 24·2 g l(-1) cell dry weight (CDW). The mathematical model obtained was validated in experiments performed in shaken-flask cultures and also in aerated bioreactors. Maximum yield and productivity values achieved were, respectively, of 0·23 g CDW/g FS in a medium containing (g l(-1) ): FS, 87·0; DAP, 7·0; YE, 1·0; and of 0·96 g CDW l(-1) h(-1) in a medium containing (g l(-1) ): FS, 150·8 plus DAP, 6·9. Optimized culture conditions for maximizing yeast biomass production determined in flask cultures were applicable at a larger scale. The highest yield values were attained in media containing relatively low-CMz concentrations supplemented with DAP and YE. Yeast extract would not be necessary if higher productivity is the aim. Cells of L. thermotolerans produced aerobically could be sustainably produced in a medium just containing cheap carbon, nitrogen and phosphorus sources. Response surface methodology allowed the fine-tuning of cultural conditions.
Protein Expression and Purification, 2014
A clone of the methylotrophic yeast Pichia pastoris strain GS115 transformed with the bovine proc... more A clone of the methylotrophic yeast Pichia pastoris strain GS115 transformed with the bovine prochymosin B gene was used to optimize the production and downstream of recombinant bovine chymosin expressed under the methanol-inducible AOXI promoter. Cell growth and recombinant chymosin production were analyzed in flask cultures containing basal salts medium with biodiesel-byproduct glycerol as the carbon source, obtaining values of biomass level and milk-clotting activity similar to those achieved with analytical glycerol. The effect of biomass level at the beginning of methanol-induction phase on cell growth and chymosin expression was evaluated, determining that a high concentration of cells at the start of such period generated an increase in the production of chymosin. The impact of the specific growth rate on chymosin expression was studied throughout the induction stage by methanol exponential feeding fermentations in a lab-scale stirred bioreactor, achieving the highest production of heterologous chymosin with a constant specific growth rate of 0.01 h À1 . By gel filtration chromatography performed at a semi-preparative scale, recombinant chymosin was purified from exponential fed-batch fermentation cultures, obtaining a specific milk-clotting activity of 6400 IMCU/mg of chymosin and a purity level of 95%. The effect of temperature and pH on milk-clotting activity was analyzed, establishing that the optimal temperature and pH values for the purified recombinant chymosin are 37°C and 5.5, respectively. This study reported the features of a sustainable bioprocess for the production of recombinant bovine chymosin in P. pastoris by fermentation in stirred-tank bioreactors using biodiesel-derived glycerol as a low-cost carbon source.
Catalysts
Dark fermentation is a hydrogen generating process carried out by anaerobic spore-forming bacteri... more Dark fermentation is a hydrogen generating process carried out by anaerobic spore-forming bacteria that metabolize carbon sources producing gas and short-chain acids. The process can be controlled, and the hydrogen harvested if bacteria are grown in a reactor with favorable conditions. In this work, bacteria selected from natural sources were grown with a defined culture media, while pH was monitored, with the aim of relating the amount of generated hydrogen to the increase in hydron ion concentration. Therefore, a model based on the acid-base species mass balance is proposed and solved to estimate the lag phase time and measure the hydrogen production efficiency and kinetics. Hydrogen production in a stirred batch reactor was performed for 150–200 h, at given operating conditions using a previously defined growth media, to validate the model. Using the proposed model, the cumulated moles of produced hydrogen correlate well with those predicted from the pH curve. Hence, the modified...
Advances in Biotechnology & Microbiology, 2018
Saccharomyces cerevisiae RC016 presents probiotic and mycotoxin adsorbent properties for use as f... more Saccharomyces cerevisiae RC016 presents probiotic and mycotoxin adsorbent properties for use as feed additive. The improvement of S. cerevisiae RC016 biomass production using an agro-industrial waste such as Dried Distillers' Grains and Solubles (DDGs) that pollute the environment can contribute to sustainable development of the process and reduce the costs of large-scale production. In order to avoid the obstruction of the fermentor's stirring mechanism with solid particles a novel pretreatment of DDGs was conducted to concentrate carbon sources levels. The design of experiments were performed using four factor-three-level Box-Behnken design (carbon source concentration, nitrogen source concentration, yeast extract concentration and incubation time) coupled with response surface methodology to evaluate the interaction between two factors in order to determine the optimum process conditions. A quadratic model was suggested for the prediction of biomass production. The F-value and p-value of the model indicated that it was statistically significant at 95 percent confidence interval. In addition, R 2 value of the model indicated an acceptable accuracy. The results were validated at bioreactor level showing that the specific growth rate on the optimized medium (0.34h-1) increased 112.5% compared to the initial non-optimized medium (0.16h-1), the duplication time showed a decrease of 52.9%. Optimization enabled productivity (0.451gL-1 h-1) nine times higher than the initial one (0.062gL-1 h-1), thus 65% more biomass was obtained (5.20gL-1). The use of biomass DDGse derived from bioethanol production promotes the sustainable and green way of biomass production.
Resumen es: Prototheca zopfii es una alga cocoide, incolora que hemos aislado del rio Reconquista... more Resumen es: Prototheca zopfii es una alga cocoide, incolora que hemos aislado del rio Reconquista en septiembre del 2000 (Argentina, Prov. de Buenos Aires, Pdo. Tig...
Summary. A statistically based Plackett-Burman screening design identified milk whey and corn ste... more Summary. A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor concentrations as well as ionic strength (based on phosphate buffer concentration) as the three main independent components of the culture medium that significantly (p < 0.05) influenced biomass and poly(3-hydroxybutyrate) (PHB) production in recombinant cells of Escherichia coli. This strain carries a plasmid encoding phb genes from a natural isolate of Azotobacter sp. Response surface methodology, using a central composite rotatable design, demonstrated that the optimal concentrations of the three components, defined as those yielding maximal biomass and PHB production in shaken flasks, were 37.96 g deproteinated milk whey powder/l, 29.39 g corn steep liquor/l, and 23.76 g phosphates/l (r 2 = 0.957). The model was validated by culturing the recombinant cells in medium containing these optimal concentrations, which yielded 9.41 g biomass/l and 6.12 g PHB/l in the culture br...
Cell Biology International Reports, 1983
Revista Iberoamericana De Micologia, 2009
Journal of Applied Polymer Science, 2015
Fil: Cerrutti, Patricia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de C... more Fil: Cerrutti, Patricia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologia En Polimeros y Nanotecnologia. Universidad de Buenos Aires. Facultad de Ingenieria. Instituto de Tecnologia En Polimeros y Nanotecnologia; Argentina
Darwiniana Nueva Serie, Jul 1, 2006
Http Digital Bl Fcen Uba Ar, 1981
tutti trim-ae, X'a temer ¡Puna es 2X (Anita f actor oetemwimxe Ue.Xa 'ÑEÏVÉARÉÉSA\SA\ÉÜGSA\:L:Ï\\... more tutti trim-ae, X'a temer ¡Puna es 2X (Anita f actor oetemwimxe Ue.Xa 'ÑEÏVÉARÉÉSA\SA\ÉÜGSA\:L:Ï\\'&Si\ük'\RRRSÁ\GAYSÑGSÏÉS\ïSÑSEÏGSi'®&É_ isa. minima: 10-18 pm de diámetro y emergencia del tubo germinativo, en el og so de desarrollo hifal; o producción de una yema esférica, en el
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Revista iberoamericana de micología, Jan 30, 2009
The aim of this study was to evaluate the vitality and viability of the probiotic yeast Saccharom... more The aim of this study was to evaluate the vitality and viability of the probiotic yeast Saccharomyces boulardii after freezing/thawing and the physiological preconditioning effect on these properties. The results indicate that the specific growth rate (0.3/h(-1)) and biomass (2-3 x10(8)cells/ml) of S. boulardii obtained in flasks shaken at 28 degrees C and at 37 degrees C were similar. Batch cultures of the yeast in bioreactors using glucose or sugar-cane molasses as carbon sources, reached yields of 0.28 g biomass/g sugar consumed, after 10h incubation at 28 degrees C; the same results were obtained in fed batch fermentations. On the other hand, in batch cultures, the vitality of cells recovered during the exponential growth phase was greater than the vitality of cells from the stationary phase of growth. Vitality of cells from fed-batch fermentations was similar to that of stationary growing cells from batch fermentations. Survival to freezing at -20 degrees C and subsequent thawi...
Revista Argentina de microbiología
Rising activity determined as CO2 production of two commercial strains of Saccharomyces cerevisia... more Rising activity determined as CO2 production of two commercial strains of Saccharomyces cerevisiae could be increased mainly in sweet bread doughs by introducing a "starvation/pulse feeding" schedule of sugar cane molasses during a fed-batch propagation. Such increase was strain dependent. Except for the trehalose intracellular level, other traits related to the yeast industrial performance were unaffected. Applicability of method for baker's yeast industrial production is discussed.
A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor... more A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor concentrations as well as ionic strength (based on phosphate buffer concentration) as the three main independent components of the culture medium that significantly (p < 0.05) influenced biomass and poly(3-hydroxybutyrate) (PHB) production in recombinant cells of Escherichia coli. This strain carries a plasmid encoding phb genes from a natural isolate of Azotobacter sp. Response surface methodology, using a central composite rotatable design, demonstrated that the optimal concentrations of the three components, defined as those yielding maximal biomass and PHB production in shaken flasks, were 37.96 gdeproteinated milk whey powder/l, 29.39 g corn steep liquor/l, and 23.76 g phosphates/l (r 2 = 0.957). The model was validated by culturing the recombinant cells in medium containing these optimal concentrations, which yielded 9.41 g biomass/l and 6.12 g PHB/l in the culture broth. Similar amounts of PHB were obtained following batch fermentations in a bioreactor. These results show that PHB can be produced efficiently by culturing the recombinant strain in medium containing cheap carbon and nitrogen sources.Un diseño estadístico de selección de Plackett-Burman identificó las concentraciones de suero de leche y de macerado de maíz, así como la fuerza iónica (dada por la concentración del tampón de fosfatos), como tres variables principales e independientes del medio de cultivo que, de forma significativa (p < 0,05), influían en el crecimiento y la acumulación de biomasa y poli(3-hidroxibutirato) (PHB) en células recombinantes de Escherichia coli. Esta cepa lleva un plásmido que codifica los genes phb provenientes de un aislado natural de Azotobacter sp. Aplicando la metodología de superficies de respuesta, mediante un diseño central compuesto direccionable, se demostró que los valores óptimos de las variables del proceso para la máxima producción de biomasa y de PHB eran: 37,96 g/l de suero de leche desproteinizado en polvo, 29,39 g/l de macerado de maíz y 23,76 g/l de fosfatos (r2 = 0,957). En la validación del modelo, realizada utilizando los valores óptimos, se obtuvieron unas concentraciones de biomasa de 9,41 g/l y de PHB de 6,12 g/l en el medio. En los ensayos en lote en biorreactor se obtuvieron contenidos semejantes de PHB. Los resultados demostraron que el biopolímero puede producirse eficazmente con esta cepa recombinante a partir de fuentes de carbono y nitrógeno de bajo costo.Fil: Nikel, Pablo Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Cátedra de Microbiología; ArgentinaFil: Pettinari, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Cátedra de Microbiología; ArgentinaFil: Mendez, Beatriz Silvia. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Ingeniería Química; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Cátedra de Microbiología; ArgentinaFil: Galvagno, Miguel Angel. Universidad Nacional de San Martín; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Fungal Ecology, 2015
The cactus-yeast-Drosophila system is a model system in evolutionary biology, and the participati... more The cactus-yeast-Drosophila system is a model system in evolutionary biology, and the participating saprotrophic microorganisms represent one of the most thoroughly studied microbial communities. However, much of the cactus-dominated regions of South America, home to endemic versions of this classical system, remain understudied. A combined morpho-physiological and molecular approach was employed to identify the fungal members of the cactus-yeast-Drosophila system in western Argentina. We identified twenty one species of saprotrophic organisms in the necroses of Opuntia sulphurea and Trichocereus terscheckii in a region of sympatry, where both cacti are exploited by cactophilic Drosophila. After excluding opportunistic isolates, we determined that the saprobe community of O. sulphurea was composed of eight species (including the first consideration of filamentous fungi as community members), whereas the community of T. terscheckii represented a subgroup of the former. We explain this nested pattern by considering the physiological and ecological attributes of both hosts and vectors involved.
Cell Biology International Reports, 1991
ABSTRXI. incubation of Candida albicans yeast cells with human luteinizing hormone (hL,RJ, human ... more ABSTRXI. incubation of Candida albicans yeast cells with human luteinizing hormone (hL,RJ, human chorionic gonadotrophin (hCG) or glucagon produced a significant rise in CAMP total levels. The effect of these hormones in permeabilie cells of the fungus produced a 2-3 fold increase in the Mg GTP-dependent adenylyl cyclase activity as well as full activation of the CAMP-dependent protein kinase (PKA) activity. These results indicate that the interaction of the mammalian hormones with the fungus triggered the CAMP activation cascade in a similar way to that found in higher eukaryotic organisms.
Cell Biology International Reports, 1990
Protein Expression and Purification, 2013
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Papers by Miguel A Galvagno