Tesis Maestría en Ciencias en Recursos Naturales y Desarrollo Rural El Colegio de la Frontera Sur 2012

Bibliografía: hojas 42-47

Capítulo 1.. Introducción General.. Objetivos.. Objetivo general.. Objetivos específicos.. Hipótesis.. Capítulo 2.. Artículo: Succession of fungi colonizing contrasting limestone lithotypes in tropical environments.. Abstract.. Introduction.. Material and Methods.. Limestone lithotypes.. Preparation of inoculum.. Experimental setup.. Meteorological monitoring.. Isolation of fungi.. Fungi identification.. Results and Discussion.. Meteorological Monitoring.. Microbial colonisation.. Culturable fungal community.. Seasonal and substratum-influenced changes on fungal Community composition.. Acknowledgments.. References.. Tables and Figures.. Capítulo.. Conclusiones Generales.. Literatura Citada

Acceso en línea sin restricciones

Little is known about the dynamics of succession of fungi on limestone exposed in tropical environments. In this study, the colonization of experimental blocks of limestone of contrasting porosity by induced fungal communities was studied using a cultivation- dependent approach after short-term exposure in Campeche, Mexico. Microbial growth seen as the change of colour of stone surfaces to black/dark green was more abundant on the porous lithotype. There was a fairly clear difference in microbial colonisation between the onset of the experiment and the 6th month for both lithotypes, but no significant increase in the colonization of coupons occurred between months 6 and 9. This could be related to the relatively low rainfall during this period, which corresponded to the dry season. A total of 977 isolates were obtained. From these, 138 were unidentified sterile fungi, 380 could only be assigned to the order Sphaeropsidales; the remaining isolates (459) were grouped into 27 genera and 99 different species. Nearly all detected fungal species belonged to the Ascomycota (90 %). Rare taxa (species represented by one to three isolates) included the recently described genus Elasticomyces sp., several species of Hyalodendron and Monodyctis (M. paradoxa, M. sp. 2 and M. sp. 4), Papulospora sp. 2, Curvularia brachyspora, C. pallescens, C. senegalensis and C. verruculosa, Septoria sp. and Tritirachium album. Other rare taxa were Glimastix luzulae and Minimedusa sp., which have not been previously described for stone environments. Abundant fungi included several species of the common genera Cladosporium, Alternaria and Taeniolella typical for a range of habitats. Succession of populations was observed for certain taxa, this shift in the composition of fungal communities was more evident in porous limestone. Inglés

After 6 months of exposure, species of the genera Scolecobasidium, Hyalodendron and Taeniolella were predominant, while after 9 months, the predominant species belonged to the genera Curvularia and Alternaria, particularly on porous stone. These results suggest that Curvularia and Alternaria replaced other fungi, due to a higher tolerance towards low levels of available water during the rainy season. High porosity keeps for longer periods water available for microbial growth, buffers the impact of desiccation. This study contributes to understanding the diversity of fungal communities in stone surfaces in tropical settings and the dynamics of colonization on limestone. Inglés

Ecología y Sistemática