The Dead Sea sinkhole pools: a source of microbial diversity in an extreme environment

The continuous desiccation of the Dead Sea has created thousands of sinkholes around the shoreline, which form a unique aquatic habitat that is forever changing. These collapsed sinkholes can be filled with various water types and the salinity within the sinkhole pools vary greatly, and many of them are infused with hypersaline brine that originated from the Dead Sea. Therefore, this unique environment provides an ideal setup for studying microbe adaptation to a changing environment at the molecular level. In this study, we aim to uncover variations in abiotic factors, such as salinity, pH, and chemical composition of the water within the sinkhole pools over time and space. We then aim to identify the specific abiotic factors that affect the dynamics of the microbial communities by metagenomic analyses. To achieve these goals, we sampled over ten sinkholes near Ein Gedi, and performed chemical and metagenomic analyses on the samples. The pH values of sinkholes varied between pools and did not significantly change throughout the year. The temperature of the sinkholes altered according to the season, while the total dissolved salts correlated with the sinkhole surface area and the pH. Metagenomic data shows that the microbial communities in the sinkholes are composed of various bacteria, archaea, and eukaryotic microorganisms, as well as DNA and RNA viruses. Preliminary data suggest that the distribution of cyanobacteria and cyanophages is limited by salinity levels. These results demonstrate that the sinkhole is a unique habitat containing various microbial communities affected by level of salinity.