Active volcanoes are among the most extreme environments on Earth. The extreme temperatures, presence of toxic heavy metals and low nutrient bioavailability favor the development of extremophiles. We characterized the physical-chemical parameters of and bacterial communities (T-RFLP and 16S rRNA gene libraries) inhabiting fumarole niches of the Paricutín volcano located in Michoacán (Mexico). This volcano, which surged in 1943, is one of the youngest volcanoes on Earth and the microbial diversity in this area is yet to be characterized. The sampling stations were characterized in a pH range from 5.34 to 7.89 and showed different temperatures (soil, 27-87 °C; air, 13.6-56 °C) with high concentrations of metals such as iron and arsenic. The most abundant bacterial populations, confirmed by T-RFLP and 16S rRNA gene libraries, were related to members of Firmicutes and Proteobacteria phyla including sequences associated with thermophiles and sulfate reducing bacteria. Overall, the Paricutín volcano showed low bacterial diversity and its prokaryotic diversity was characterized by the impossibility of amplifying Archaea-related sequences.

In Mexico, the genus Uranotaenia includes 11 species distributed mainly in the tropical and subtropical regions in the southeast of the country. Uranotaenia sapphirina has been reported in 18 states in Mexico: Campeche, Coahuila, Colima, Chiapas, Guerrero, Hidalgo, Jalisco, Mexico City, Mexico State, Michoacán, Morelos, Oaxaca, Quintana Roo, Sinaloa, Tabasco, Tamaulipas, Veracruz, and Yucatán; whereas Ur. socialis has been reported in Chiapas and Quintana Roo. In recent surveillance studies of mosquito species in Tabasco, Ur. sapphirina and Ur. socialis were omitted due to the lack of recent collection records, but in historical records, the presence of Ur. sapphirina and one species consistent with the description of Ur. socialis were mentioned. During a mosquito survey collection, immature stages from ground-level natural habitats in conservation areas of Tabasco, Ur. sapphirina and Ur. socialis were collected in association with Anopheles albimanus, Culex erraticus, Mansonia titillans, and Ur. lowii. Additionally, 2 Mexican entomological collections were reviewed, searching additional records of those species. An identification key to separate larvae and adult females of Ur. sapphirina and Ur. socialis is provided. With the addition of Ur. sapphirina and Ur. socialis to the mosquito fauna of Tabasco, there are currently 107 species in the state, being the 3rd state in Mexico with the highest richness of mosquito species. Specimens collected during this study were deposited in the Collection of the Entomological and Bioassay Research Unit of Tabasco.

Las lagunas de estabilización (LE) se utilizan como una alternativa para el tratamiento de aguas residuales; sin embargo, una de sus desventajas es la emisión de malos olores ocasionados por el ácido sulfhídrico (H2S), el cual es altamente tóxico y corrosivo, además de que provoca daños a la salud de la población aledaña y afecta negativamente a las estructuras metálicas y equipos eléctricos expuestos. Esta problemática es una prioridad para resolver y continuar con la operación de las plantas de tratamiento de agua residual. En este estudio se presenta como alternativa de solución un procedimiento basado en la recirculación del efluente de 20%, el cual contiene microalgas nativas. Para determinar el porcentaje óptimo de recirculación del efluente, se implementó una serie de pruebas de recirculación a través del método de jarras y posteriormente fue llevado a escala macro, evaluando el desempeño de la recirculación del efluente comparando los promedios mensuales del año 2019 antes de la implementación del proyecto con 2020 ya operando. Los resultados mostraron cambios significativos en los porcentajes de remoción de contaminantes, en la demanda bioquímica de oxígeno, de 20.8%, solidos suspendidos totales, 22.17%, grasas y aceites, 29.5% y una reducción en los coliformes fecales, 91.4%, además de reducción del H2S con un 48.9%, lo que disminuye los olores desagradables y potencial efecto toxico a la salud. Podemos concluir que la metodología es eficiente en la mejora de los parámetros antes mencionados, cumpliendo así los estándares de las normativas aplicables.