Evaluación de la respuesta fisiológica de la microalga Chlorella sp. a la presencia de metal Cadmio en aguas sintéticas

Abstract

Different sources of water are contaminated with metals, which bioaccumulate causing serious damage to biological diversity. Chlorella has a great ability to retain metal and has been used in bioremediation techniques. The objective of this study is to evaluate the physiological response of the microalga Chlorella sp. to the presence of cadmium, where the photosynthetic activity of the microalga exposed to 6 different concentrations of cadmium (Cd) and different pH values (4, 6, 8). In order to study the effect of metal, growth was evaluated by cell quantification and Neubauer chamber every 24 hours. The photosynthetic activity of the microalga was compared by means of the quantification of liposoluble pigments with spectrophotometric methods, by means of two readings: one at the beginning (0 hours) and another at the end (96 hours) of the test at the following wavelengths: 662, 665 and 470 (nm). Finally, the median lethal concentration (LC50) of cadmium was determined on the microalgae by applying Probit analysis. Thus, it was determined that the different pH values are influential factors in the activity of Chlorella sp., pH 4 being the most harmful and pH 6 and 8 favor the growth and photosynthetic activity; between metal concentrations, there is no significant difference however 60 mg/L is the most influential. The LC50 for pH 4 is 7.67 mg/L, for pH 6 it is 80.66 mg/L and for pH 8 it is 102.5 mg/L.