Does Microbial Diversity of Cave Ecosystems Differ from Outside? The Case of the Azé Show Cave (France)

Abstract In recent decades, the Azé cave has begun to suffer from microorganism proliferation due to artificial lighting installations for touristic activity. The present work aims at understanding the origin of the Lampenflora and bacterial community populating inside the cave. We performed high throughput sequencing of the communities populating the outside, the entrance and the inside of the Azé cave. Our results indicated that 68.2–74.5% of the phototrophic community was represented by Eukaryotes, and 25.5 to 31.8% by cyanobacteria regardless of the sampled area. We observed a decrease of bacterial and phototroph species richness from the outside to the bottom of the cave. The phototrophic communities were significantly different in term of specific OTU richness but not in term of composition. For photosynthetic organisms, only 4 OTU were specific to the inside of the cave, representing less than 0.1% of the total OTUs. On the contrary, more than 400 bacterial OTUs were specific to the inside of the cave. These metabarcoding-based findings in the Azé cave revealed a complex community structure that is similar but less diverse in comparison to the outside.