Determination of the effect of caving activities on cave microbial diversity

Caves defined as underground natural geological opening are characterized by extreme environmental conditions such as darkness, low but stable temperature, high humidity, and low nutrient. The presence of microorganisms in these extreme ecosystems is interesting. Their adaptation in these extreme conditions indicates the presence of important genes which can be used for the synthesis of important biological substances which could be used in biotechnological and industrial fields. However, to exploring these underground ecosystems, cavers are camping inside caves along their expedition. In this concept, this study had aimed to evaluate the impacts caused by caver activities on the cave microbial diversity. We studied the microbial profile of the surface and sediment samples taken before and after a camp period, from different areas around a camp installed at -1040m of Morca Cave, in Turkey. The Archaea and Bacterial taxonomy of this part of the cave was determined through the samples taken before the camp. Three phyla of Archaea, Thaumarchaeota, Euryarchaeota and Nanoarchaeaeota were identified. Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Planctomycetes, Gemmatimonadetes and Acidobacteria were identified as dominated Bacteria. No human indicator microorganisms (bacteria/archaea) were identified in the samples taken after the camp period, but a decreasing of the microbial diversity was observed in the selected toilet 2 and near the camping areas. Besides, Bacteroidetes members were importantly increased, after the camp, in the sediment sample from the camp area. Furthermore, after the camp, the Gram-positive bacteria including Firmicutes were increased in all the samples with an important increasing rate. At the end, as shown in Shannon and Simpson indexes of the alpha diversity, the sampled areas where human activities were less observed were noted with an increase of microbial diversity after the camp.