EPS degradation by microorganisms from hypersaline environment microbial mats

Microbial mats are complex organo - sedimentary structures and their self-sustainability, tight element cycling and relatively simple microbial composition are unique characteristics. Complex extracellular polymeric substances (EPS) are produced by the microbial communities that compose this ecosystem. Given their known metabolic capabilities, this research focused on the possibility of fungi being the primary decomposers of those secretions. Samples collected from a developing and a more mature mat were cultured in xanthan gum media (model EPS) and different treatments were applied. Degradation by monocultures of bacteria and, fungi and combined cultures of these were monitored with the Phenol-sulfuric assay. Change in community structure was assessed by molecular techniques and EPS-degrading organisms were isolated from the enrichment cultures. Results from these analysis showed that the bacterial groups are the primary degraders of the EPS. TRFLP community analysis reinforced those results by displaying that fungal communities became scarce in EPS enriched cultures. Six fungal and 4 bacterial isolates were isolated from the enriched cultures belonging to groups related to microbial mats and other hypersaline environments.