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RESUMEN Lemna minuta es una macrófita flotante de amplia distribución en ecosistemas lénticos, que puede ser útil en el desarrollo de experimentos ecofisiológicos y ecotoxicológicos debido a su potencial sensibilidad a contaminantes acuáticos como toxinas y metales pesados. Para estos, inicialmente se deben establecer cultivos axénicos con sus poblaciones bajo condiciones de laboratorio, los cuales requieren técnicas de limpieza para sus frondas que aún no han sido definidas. Se adaptó el método de Acreman en su tiempo de exposición y concentración de hipoclorito de sodio, propuesto para la desinfección de las especies pertenecientes al género Lemna L. (Lemnoideae) a partir de colonias nativas. Las colonias se obtuvieron de un humedal de la ciudad de Bogotá, y posteriormente se aclimataron y desinfectaron en diferentes tiempos y soluciones de hipoclorito. Los resultados más adecuados para la remoción de algas epífitas y otros microrganismos de las frondas, sin presentar alta mortalidad de las colonias, se obtuvieron, respectivamente, en las concentraciones 0,5 % (45 y 30 segundos) y 0,25 % (60 segundos) de hipoclorito. Por el contrario, el tiempo de exposición de 60 segundos propuesto por el método Acreman (0,5%) resultó en la mortalidad total de las frondas (100 %). Se sugiere utilizar una solución de hipoclorito de sodio 0,5% en un tiempo de exposición menor o igual a 45 segundos para la desinfección de colonias de L. minuta con fines experimentales.
ABSTRACT Lemna minuta is a floating macrophyte widely distributed in lentic ecosystems, which may be useful for development of ecophysiological and ecotoxicological experiments, due to its sensitivity to water pollutants such as toxins and heavy metals. Axenic cultures and cleaning techniques of fronds from their populations under laboratory conditions have not yet been defined. Acreman method was modified in exposure time and concentration of sodium hypochlorite for disinfection from native colonies of species belong to genus Lemna L. (Lemnoideae). The colonies were obtained from an urban wetland of Bogota city, and they were acclimatized and disinfected at different times with hypochlorite solutions. The most suitable results for the removal of epiphytic algae and other microorganisms of the fronds, without showing high mortality of colonies, were obtained, respectively, in 0,5 % (45 and 30 seconds) and 0,25 % (60 seconds) hypochlorite concentrations. By contrast, the exposure time of 60 seconds proposed by Acreman method (0,5 %) resulted in total mortality of fronds (100 %). This report suggests use a solution of 0,5 % sodium hypochlorite in an exposure time of 45 seconds or less for disinfect colonies of L. minuta with experimental purposes.
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Aims: Bioethanol is an environmental friendly energy source with a lot of great prospective and become an alternative to fossil fuels .Oil palm frond juice (OPFJ) is a potential sources of sugars for bioethanol production. The present study aimed to optimize bioethanol production. Methodology and results: Bioethanol fermentation was carried out by Saccharomyces cerevisiae HC10 using OPFJ as substrate in bioreactor with 1.5 L working volume. Growth profile was performed for 42 h with sampling every 3 h interval. Effect of agitation speed (rpm) and volume of OPFJ were screened to select significant factor for high production of bioethanol. Agitation speed at 175 rpm and volume of oil OPFJ; 40% gave 5.25 g/L and 4.52 g/L of ethanol and biomass concentration, respectively. These parameters were further investigated via central composite design (CCD) of Response Surface Methodology (RSM) to maximize bioethanol production. The suggested optimum conditions for bioethanol production were agitation speed at 152 rpm and volume of OPFJ at 39.71% in which giving ethanol concentration of 4.79 g/L. Growth profile after optimization indicated that the highest ethanol concentration (5.75%) was achieved after 15 h of fermentation. Kinetic studies indicated that ethanol yield coefficient (Yp/s) due to consumption of OPFJ and productivity of ethanol was 3.5 fold and 25% increased compared to before optimization, respectively. While, in term of ethanol yield about 9% increased was observed. Conclusion, Significance and Impact of study: This showed that OPFJ can be an alternative new feedstock for bioethanol production using S. cerevisiae HC10.
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OBJECTIVE: To establish a method to determine three main flavones in the extract of rhizomes and frond bases of Matteuccia struthiopteris and evaluate the antioxidative activity of the extract. METHODS: The contents of the flavones in the extract were determined by HPLC. Kromasil C18 column was used. Methanol-0.1% orthophosphoric acid solution (70:30) was used as the mobile phase at a flow rate of 1.00 mL· min-1. The detection wavelength was set at 295 nm and the column temperature was 40°C. The antioxidative activity of the extract was detected by DPPH free radical scavenging assay. IC50 (the antioxidant concentration for scavenging half of DPPH radical) was used as the index to evaluate scavenging capacity. RESULTS: The calibration curves of demethoxymatteucinol, matteucinol, and matteuorien showed good linearity over the ranges of 0.058 - 0.58, 0.045 - 0.45, and 0.003 - 0.028 mg· mL-1 (r = 0.9998, 0.9998, 0.9983), respectively. The average recoveries were 96.93%, 97.15%, and 96.41%, respectively. The IC50 value of the extract of rhizomes and frond bases of Matteuccia struthiopteris was 0.55 mg· mL-1. CONCLUSION: The quantitative determination method with good accuracy, repeatability and stability is suitable for the quality control of the extract of rhizomes and frond bases of Matteuccia struthiopteris. The extract has potential antioxidative action.