Estimation of Prokaryotic Diversity in Two Algerian Hot Springs Using High-Throughput Sequencing Methods

Natural hot environments can represent an important source of microbial biodiversity and biomole¬cules with great added value. In this work, we compare the diversity of prokaryotic communities in Debagh and Ouled Ali, two terrestrial hot springs located in the province of Guelma (Algeria) using high-through¬put sequencing methods. Environmental DNA was extracted from 23 sediment samples collected from 4 sampling sites of these hot springs. Sequences of the V4 hypervariable region of the environmental 16S rRNA gene were obtained by the MiSeq Illumina technique. The bioinformatic generation of operational taxonomic units (OTUs) made it possible to estimate the diversity of thermophilic prokaryotes in each sam¬ple. The identification of OTUs indicated that of the 2,356,656 sequences retained by the analysis, 91.41% belonged to the domain of Bacteria, against 8.59% belonging to the domain of Archaea. Rarefaction curves indicated that none of the samples from Ouled Ali reached an asymptote, in opposition to samples from De¬bagh. Alpha and Beta diversity analysis showed higher diversity values when temperatures were the lowest with significant differences between the four sites. The study of the abundance of prokaryotic communities at three taxonomic levels (phyla, families, and genera) revealed that aerobic thermophilic bacteria affiliated with Deinococcota, Aquificia, Chloroflexota, and aerobic archaeal groups of Crenarchaeota and Thaumar¬chaeota were the most dominant. Among these groups, 18 archaeal genera, and 276 bacterial genera were present in all samples of the 4 studied sites while 25 archaeal genera and 399 bacterial genera were unique to the different sites.