Effect of organic matter enrichment on the fungal community in limestone cave sediments.

Caves are considered major touristic attractions. The management plans of many such caves include limiting the number of visitors; however, the human impact on microbial communities within caves is rarely considered. Therefore, the aim of this study was to evaluate the impact of human-transferred organic matter on the fungal microcosms growing on cave sediments. Samples were collected from a Brazilian limestone cave and cultured with 0.25 or 0.5% 1: 1 (w/w) beef and yeast extract (simulating organic matter) under laboratory conditions. The contaminated fungal community was then evaluated at days 0, 30, 180, and 365 after inoculation by polymerase chain reaction denaturing gradient gel electrophoresis. We observed changes in the fungal communities with time, as well as the concentration of added organic matter, compared to the control fungal communities. Additionally, the contaminated microcosms showed a greater number of operational taxonomic units compared to the controls. These findings suggest that tourist activity could cause fungal outbreaks of possible human pathogens, demonstrating the importance of fungal monitoring in these caves.