Metataxonomic analysis of halophilic archaea community in two geothermal springs sources in southern Tunisian Sahara

Abstract

In this study, we assess the phylogenetic diversity of the halophilic archaeal community of biotechnological interest that inhabit in geothermal water in southern Tunisia. These waters are usually used for farming purposes, particularly for irrigation of the oases and greenhouses, due to the limited availability of surface freshwater resources and the arid climate. The samples processed from two separated geothermal sources in southern Tunisia based on the Illumina Miseq sequencing approach. Three samples including water, sediment, and halite-soil crust, were collected from downstream of two geothermal springs of Ksar Ghilane (KGH) and Zaouet Al Aness (ZAN) oases. Results showed that several haloarchaea-related members were identified in geothermal springs. The average taxonomic composition showed that 20 genera out of 33 were shared between the two geothermal sources with uneven distribution, where the Halogranum genus is the most represented genus with an abundance of 18.9% and 11.58% for ZAW and KGH, respectively. Several unique site-specific genera were also observed; the case of Halonotius, Halopelagius, Natronorubrum, and Haloarcula in ZAN, and Haloprofundus, Halomarina, Halovivax, Haloplanus, Natrinema, Halobium, Natronoarchaeum, Haloterrigena detected in KGH pool. We noticed that the majority of genus members are usually found in low-salinity ecosystems. The finding of this study suggests that haloarchaea-related members could survive in downstream geothermal sources, which may have resulted from the leaching of salts and minerals through drilling waters creating chemically complex saline systems.