RESUMEN Los ecosistemas de alta montaña cuentan con características ambientales únicas, proveen recursos naturales indispensables para el mantenimiento de la vida y representan puntos de alta biodiversidad y endemismo de algunas especies vegetales y animales. Dentro de la gran diversidad biológica que caracteriza estos ambientes, se resalta la microbiana por el papel principal que ésta tiene en la estabilidad y equilibrio del ecosistema. Los microorganismos establecen interacciones biológicas importantes con las plantas nativas de la región, incluyendo a las diferentes especies de Espeletia, permitiendo mejorar las características de las mismas y optimizando el rol de este tipo de ecosistemas en la regulación de las fuentes hídricas. Por tanto, esta revisión tiene como objetivo consolidar el conocimiento actual acerca de la diversidad microbiana presente en suelos de alta montaña, destacar la microbiota asociada con Espeletia spp. y sus posibles interacciones.

ABSTRACT High mountain ecosystems have unique environmental characteristics, provide essential natural resources for the maintenance of life, and represent hotspots of biodiversity and endemism for animal and vegetal species. Within the vast diversity that characterizes high mountain environments, microbial diversity stands out due to its key role in the maintenance of soil stability and sustainability, promoting plant growth through the transformation of complex substances present in the environment into bioavailable forms, exerting biocontrol over phytopathogens or through the secretion of hormones and other compounds that allow better foliar and root development. Microorganisms establish important biological interactions with native plants in high mountains and páramos, including the different species of Espeletia, thus allowing to improve their role as regulators of water sources. Therefore, this review aims to consolidate the current knowledge about the microbial diversity present in high mountain soils, highlighting the microbiota associated with Espeletia spp. and their possible interactions.

In this study, we evaluated the effect of low and high molecular weight polycyclic aromatic hydrocarbons (PAHs), i.e., Phenanthrene, Pyrene and Benzo[a]pyrene, on the radial growth and morphology of the PAH-degrading fungal strains Aspergillus nomius H7 and Trichoderma asperellum H15. The presence of PAHs in solid medium produced significant detrimental effects on the radial growth of A. nomius H7 at 4,000 and 6,000 mg L−1 and changes in mycelium pigmentation, abundance and sporulation ability at 1,000–6,000 mg L−1. In contrast, the radial growth of T. asperellum H15 was not affected at any of the doses tested, although sporulation was observed only up to 4,000 mg L−1 and as with the H7 strain, some visible changes in sporulation patterns and mycelium pigmentation were observed. Our results suggest that fungal strains exposed to high doses of PAHs significantly vary in their growth rates and sporulation characteristics in response to the physiological and defense mechanisms that affect both pigment production and conidiation processes. This finding is relevant for obtaining a better understanding of fungal adaptation in PAH-polluted environments and for developing and implementing adequate strategies for the remediation of contaminated soils.

The aim of this study was to test the possible implication of toll-like receptor 2 (TLR2) and TLR4 gene polymorphisms in determining the susceptibility to Chagas' disease. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism in 475 individuals from Colombia, 143 seropositive with chagasic cardiomyopathy, 132 seropositive asymptomatic and 200 seronegative. The TLR2 arginine to glutamine substitution at residue 753(Arg753Gln) polymorphism was absent in the groups analyzed. The TLR4 Asp299Gly and Thr399Ile polymorphisms are in linkage disequilibrium and we observed a very low frequency of these polymorphisms in our study population (2.6% and 1.8% respectively). The overall TLR2 and TLR4 alleles and genotype distribution in seronegative and seropositive were not significantly different. We compared the frequencies between asymptomatic patients and those with chagasic cardiomyopathy and we did not observe any significant differences in the distribution of alleles or genotypes. In summary, this study corroborates the low frequency of TLR2 and TLR4 polymorphisms observed in other populations and suggest that these do not play an important role in Chagas' disease. The validation of these findings in independent cohorts is needed to firmly establish a role for TLR2 and TLR4 variants in Chagas' disease.

Introducción. La enfermedad de Chagas constituye un grave problema de salud pública en Latinoamérica; en Colombia existen en gran parte de su geografía las condiciones ecoepidemiológicas propicias para la transmisión activa de esta enfermedad. Objetivo. En este estudio fue evaluada una población del municipio de Morroa, departamento de Sucre, para identificar factores de riesgo y determinar la seroprevalencia a la enfermedad de Chagas. Materiales y métodos. A una muestra de 122 personas pertenecientes al área rural (n=76) y urbana (n=46), se les aplicó una encuesta epidemiológica y se les realizó un tamizaje serológico con la prueba Elisa, confirmación de seropositivos con hemoaglutinación indirecta (HAI) (Chagatest®) y reacción en cadena de la polimerasa (PCR) como prueba parasitológica confirmatoria. Resultados. Cuatro de las personas resultaron positivas para Elisa (3,28%); sin embargo, fueron negativas a HAI y PCR. La serología discordante fue definida con prueba de inmunofluorescencia indirecta (IFI), encontrándose una de las cuatro personas positivas. La población analizada mostró una baja presencia de anticuerpos anti-Trypanosoma cruzi. No fue posible determinar la presencia del parásito en sangre usando la prueba PCR. Los principales factores de riesgo presentes fueron casas con techos de palmas, piso de tierra, paredes de bahareque y madera, y la presencia de reservorios (animales domésticos). Conclusiones. Nuestros resultados indican que la zona estudiada presenta elementos de riesgo para el establecimiento de un ciclo de transmisión activa, se hace necesario verificar la presencia de triatominos en la zona de estudio y establecer medidas para prevenir la presencia de la enfermedad de Chagas en el área de Morroa, Sucre.

Introduction. Chagas disease is a major public health problem in Latin America. In Colombia, a large area has the ecoepidemiological conditions which favor the active transmition of this infection. Objective. This study was undertaken in a population from the municipality of Morroa, Sucre Province, to evaluate risk factors and to determine the seroprevalence to Chagas disease. Materials and methods. A questionnaire was given to a sample population of 122 people classed as rural (n=76) or urban area (n = 46). A serological screening was undertaken by Elisa test, with confirmation of seropositives with IHA (Chagatest®) and parasitological confirmation by polymerase chain reaction (PCR). Results. Four people were positive by Elisa test (3.3%); however, they were negative by IHA and PCR. One of the four positives by Elisa was positive by indirect immuno flourescence (IFAT) as well. The sample showed a low presence of seropositives against Trypanosoma cruzi. However, the presence of parasite could not be confirmed by the PCR test.The main risk factors were houses thatched with palm roofs, clay floors, wood walls, and presence of domestic animal reservoirs. Conclusions. The study population presented risk factors for the establishment of active transmission. The presence of triatomines must be verified in this area and establishment of control measures are necessary for preventiving the resurgence of the Chagas disease in Morroa.