Microorganisms can adapt to extreme environmental conditions with respect to temperature, pH, desiccation and salinity. One of the more interesting extreme habitats in which microbes thrive are hypersaline mats. Prior studies of these systems have emphasized bacteria and algae and largely ignored the possible role of fungi. Recent results from the PI's laboratory have revealed that fungi can, indeed, be isolated from hypersaline mats, although it is not yet clear whether they are merely contaminants or residents that contribute to mat activities. Microbial mats are found under conditions ranging from freshwater to hypersaline. They consist of complex, laminate microbial communities that are functionally integrated and self-sustaining. Daily and seasonal fluctuations in the physical and chemical conditions (predominantly the light regime) result in both mat stratification and development of microenvironments that harbor specific microbial populations. Prokaryotes, predominantly cyanobacteria, in mats produce large quantities of extracellular polymeric secretions (EPS) consisting of complex carbohydrates. These complex secretions are consumed by other microorganisms in the mats. It is highly likely that fungi in concert with heterotrophic bacteria contribute to the degradation of EPS and the subsequent mineralization of carbon. Accordingly, this project will study the diversity, structure and function of the fungal community, present in both temperate and tropical microbial mat systems through time and space. Work includes isolation of fungi from temperate microbial mats, characterization of different isolates using physiological and molecular techniques, including sequencing and phylogenetic analysis of ribosomal RNA genes, and extraction of DNA directly from the microbial mats to construct a genomic library and study the structure of the fungal community using molecular fingerprinting methods. The techniques that will be used in this study will help elucidate the diversity and similarities of tropical and temperate microbial mats, and their role in the carbon cycle.
This project will support the career development of the PI, Dr. Sharon Cantrell, at the Univesidad del Turabo (Puerto Rico) and will provide training opportunities for Hispanic-American undergraduate and graduate researchers. It will expose Hispanic students to technology and instrumentation in the areas of mycology and molecular biology and evolution. As part of the educational and outreach activities, a TV program will be prepared to promote the importance of fungi in the environment, with emphasis in microbial mats, and the possible role of fungi therein. This project will also promote research collaborations with local, national and international universities and will enhance the infrastructure at the PI's institution.
