Efecto de la salinidad y pH en la composición bioquímica de la microalga Scenedesmus sp. (UGB-RJ.3009) en cultivos discontinuos
Fecha
2019
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Facultad de Ciencias Naturales. Universidad de Guayaquil
Resumen
En el presente estudio se evaluó el efecto del pH (5, 6, 9,11) y de la salinidad (6, 12, 26 y 36 UPS) en el crecimiento y la producción de pigmentos, proteínas, carbohidratos y lípidos de la microalga Scenedesmus sp. en el medio de cultivo BG11. Los cultivos discontinuos se mantuvieron por 19 días, con aireación constante, irradiancia de 50.22 μmol m-2s-1, fotoperiodo 12:12 h y a 25±2 ºC. Entre los resultados se determinó que en cultivos no salinos y a pH 9 se presentaron las densidades celulares más elevadas con 9.48±0.32x106 cél.mL-1 con diferencias significativas p<0.05 entre el control (pH 8-10) y el rango de pH estudiados. Mientras, que los de clorofila a y b se produjeron a 0 UPS y pH (8-10) con 5.52±0.09 y 2.03±0.16 μg.mL-1, respectivamente, pero con un descenso con el aumento de NaCl. Así mismo, se demostró que los carotenoides se incrementaron a 12UPS y pH 11 de 0.20±0.004 a 1.45±0.004 μg.mL-1 y el más elevado en lípidos (p<0.05) se evidenció a 6 UPS con 16±32.37 μg.mL-1. Sin embargo, los mayores contenidos de proteínas y carbohidratos se produjeron a 0UPS y pH 11 con 377.37±23.88 y 122.69±1.68 μg.mL-1; respectivamente; demostrándose que el efecto del pH tuvo mayor influencia en la acumulación de proteínas y carbohidratos. Los resultados de la adaptación gradual al NaCl permiten concluir que esta cepa de Scenedesmus sp., aunque es halotolerante presentó un crecimiento óptimo, mayor contenido de clorofila y de carotenoides en condiciones no salinas y en medio alcalino.
In the present study, the effect of pH (5, 6, 9, 11) and salinity (6, 12, 26 and 36 UPS) on the growth and production of pigments, proteins, carbohydrates and lipids of the microalgae was evaluated. Scenedesmus sp. in the BG11 culture medium. The discontinuous cultures were maintained for 19 days, with constant aeration, irradiance of 50.22 μmol m-2s-1, photoperiod 12:12 h and at 25 ± 2 ºC. Among the results, it was determined that in non-saline cultures and those at pH 9 presented the highest cell densities having 9.48 ± 0.32x106 cells.mL-1 with significant differences of p <0.05 between the control (pH 8-10) and the pH range studied. Meanwhile, chlorophyll a and b were produced at 0 UPS and pH (8-10) with 5.52 ± 0.09 and 2.03 ± 0.16 μg.mL-1, respectively, but with a decrease with the increase in NaCl. Likewise, it was shown that carotenoids were increased to 12UPS and pH 11 from 0.20 ± 0.004 to 1.45 ± 0.004 μg.mL-1. In contrast, the highest in lipids (p <0.05) was evidenced at 6 UPS with 16 ± 32.37 μg.mL-1. However, the highest protein and carbohydrate contents were produced at 0UPS and pH 11 with 377.37 ± 23.88 and 122.69 ± 1.68 μg.mL-1; respectively; demonstrating that the effect of pH had a greater influence on the accumulation of proteins and carbohydrates. The results of the gradual adaptation to NaCl allow us to conclude that this strain of Scenedesmus sp. although it is halotolerant, showed an optimal growth, a higher content of chlorophyll and of carotenoids in non-saline conditions and in an alkaline medium.
In the present study, the effect of pH (5, 6, 9, 11) and salinity (6, 12, 26 and 36 UPS) on the growth and production of pigments, proteins, carbohydrates and lipids of the microalgae was evaluated. Scenedesmus sp. in the BG11 culture medium. The discontinuous cultures were maintained for 19 days, with constant aeration, irradiance of 50.22 μmol m-2s-1, photoperiod 12:12 h and at 25 ± 2 ºC. Among the results, it was determined that in non-saline cultures and those at pH 9 presented the highest cell densities having 9.48 ± 0.32x106 cells.mL-1 with significant differences of p <0.05 between the control (pH 8-10) and the pH range studied. Meanwhile, chlorophyll a and b were produced at 0 UPS and pH (8-10) with 5.52 ± 0.09 and 2.03 ± 0.16 μg.mL-1, respectively, but with a decrease with the increase in NaCl. Likewise, it was shown that carotenoids were increased to 12UPS and pH 11 from 0.20 ± 0.004 to 1.45 ± 0.004 μg.mL-1. In contrast, the highest in lipids (p <0.05) was evidenced at 6 UPS with 16 ± 32.37 μg.mL-1. However, the highest protein and carbohydrate contents were produced at 0UPS and pH 11 with 377.37 ± 23.88 and 122.69 ± 1.68 μg.mL-1; respectively; demonstrating that the effect of pH had a greater influence on the accumulation of proteins and carbohydrates. The results of the gradual adaptation to NaCl allow us to conclude that this strain of Scenedesmus sp. although it is halotolerant, showed an optimal growth, a higher content of chlorophyll and of carotenoids in non-saline conditions and in an alkaline medium.
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CARBOHIDRATOS, CRECIMIENTO, LÍPIDOS, pH, PROTEÍNAS, SALINIDAD, SCENEDESMUS SP.