ABSTRACT Mining operations in the south of Ecuador have increased their activity in the last decades due to the great auriferous wealth of the region. Nevertheless, gold extraction involves processes that cause dangerous impacts to the environment, such as the release of metal ions and inorganic compounds, which are discharged into aquatic systems or to the earth’s surface, interacting adversely with various organisms. Due to this problem, the aim of this research was to evaluate the removal efficiency of mercury, phosphates, sulfates, and nitrates from the gold mining wastewater through a phytoremediation process. The study collected and applied microalgae species of the Andes and the Ecuadorian Amazon such as Pleurococcus sp., Scenedesmus sp., and Chlorella sp. The adaptation of the microalgae was evaluated, as well as the absorption capacity of the pollutants of the wastewater collected from one of the gold processing plants located on the riverside of the Calera River, province of El Oro. The microalgae strains were cultivated individually and as a consortium in photobioreactors for the treatment. The physical and chemical parameters of the wastewater and the treated water were characterized. The results determined that all the treatments were efficient, since the concentration of contaminants was considerably reduced. Pleurococcus was the genus of microalgae with the highest percentage of mercury removal, with 86 %, while in the removal of sulfates, phosphates, and nitrates, the microalgae consortium achieved results greater than 76 %, 93 % and 97 %, respectively. Thus, the use of isolated microalgae on the lacustrine systems of the Andes and the Ecuadorian Amazonia represents a promising source of germplasm for environmental bioremediation applications.

RESUMEN La explotación minera en el sur del Ecuador ha incrementado su actividad en las últimas décadas debido a la gran riqueza aurífera de la región. No obstante, la extracción de oro involucra procesos que causan impactos perjudiciales al ambiente, tales como la liberación de iones metálicos y compuestos inorgánicos, mismos que son vertidos a sistemas acuáticos o a la superficie terrestre, interactuando de manera adversa con diversos organismos. Debido a esta problemática, el objetivo de esta investigación fue evaluar la eficiencia de remoción de mercurio, fosfatos, sulfatos y nitratos del agua residual provenientes de la actividad minera a través de un proceso de ficorremediación mediante el uso de las microalgas Pleurococcus sp., Chlorella sp. y Scenedesmus sp., cepas aisladas de los Andes y la Amazonía ecuatoriana. Se valoró la adaptación de las microalgas, así como la capacidad de biosorción de los contaminantes del agua residual recolectada del punto de descarga de una de las plantas de beneficio, ubicada a orillas del río Calera, provincia de El Oro, Ecuador. Las microalgas fueron cultivadas para el tratamiento del agua de forma individual y como consorcio en fotobiorreactores. Se caracterizaron los parámetros físicos y químicos del agua residual y del agua tratada, determinándose que todos los tratamientos fueron eficientes, ya que se redujo considerablemente la concentración de contaminantes. El género de microalga con el que mayor porcentaje de remoción de mercurio se obtuvo fue Pleurococcus con el 86 %; mientras que, en la remoción de sulfatos, fosfatos, y nitratos, el consorcio de microalgas alcanzó resultados de remoción de contaminantes mayores al 76 %, 93 % y 97 %, respectivamente. Por lo tanto, el uso de microalgas aisladas en los sistemas lacustres de los Andes y la Amazonía del Ecuador representa una fuente de germoplasma promisorio para aplicaciones de biorremediación ambiental.

ABSTRACT Chicha, a type of beer made mainly with maize or cassava, is a traditional fermented beverage of the Andean region. There have only been a few studies on yeasts associated with chicha fermentation, and the species diversity occurring during the production of this beverage is not known. The objective of this study was to determine the biodiversity of yeasts in chicha, and to characterize the Saccharomyces cerevisiae populations associated with the production of chicha de jora, seven-grain chicha, chicha de yuca, and chicha de morocho in Ecuador. The molecular diversity of S. cerevisiae populations was determined by restriction polymorphism mitochondrial profiles. The beverages were characterized based on their physicochemical parameters. Twenty-six species were identified, and the most prevalent species were S. cerevisiae and Torulaspora delbrueckii. Other yeast species were isolated at low frequencies. Among 121 isolates of S. cerevisiae, 68 different mtDNA molecular profiles were identified. These results showed that chichas are fermented by a high number of different strains of S. cerevisiae. Some other species provided a minor contribution to the fermentation process. The chicha presented generally similar physicochemical parameters to those observed for other traditional fermented beverages, and can be considered as an acid fermented beverage.