fa تخصصي Special پژوهشي Research <span style="font-size:12pt"><span style="line-height:120%"><span style="font-family:&quot;Times New Roman&quot;,serif">Hypersaline lakes are extreme ecosystems that harbor specialized microbial communities adapted to high osmotic stress. Lake Urmia, one of the world&rsquo;s largest hypersaline lakes, has undergone pronounced salinity fluctuations (>340 g L⁻&sup1;), providing a natural system for studying microbial community structure under extreme conditions. In this study, bacterial diversity in Lake Urmia was assessed using PCR-DGGE targeting the V3 region of the 16S rRNA gene. Water samples were collected from six sites in northern and central regions during spring and summer 2013. Community patterns were analyzed using DGGE fingerprinting combined with ecological indices and multivariate statistics, including UPGMA clustering and Bray&ndash;Curtis similarity analysis.&nbsp; Shannon diversity indices ranged from 1.21 to 2.08 and Simpson indices from 0.28 to 0.64, indicating moderate diversity with significant spatial heterogeneity (ANOVA, p < 0.05). Cluster analysis resolved two distinct community structures corresponding to northern and central lake regions, with >60% dissimilarity. Sequencing of representative DGGE bands revealed taxa affiliated with Proteobacteria, Bacteroidetes, and Actinobacteria. Several sequences showed <97% similarity to known organisms, suggesting the presence of potentially novel halophilic lineages. Notably, <i>Deefgea rivuli</i> and multiple uncultured bacterial groups were detected for the first time in Lake Urmia. These findings demonstrate strong spatial structuring of bacterial communities in response to environmental heterogeneity and highlight Lake Urmia as a reservoir of underexplored microbial diversity.</span></span></span><br> &nbsp; Lake Urmia, hypersaline lake, bacterial diversity, 16S rRNA gene, PCR-DGGE, microbial community structure, multivariate analysis, halophilic bacteria 127 136 http://injbir.com/browse.php?a_code=A-10-1-48&slc_lang=fa&sid=1 R. Manaffar 1003194753284600697 1003194753284600697 Yes Department of Fisheries, Faculty of Natural Resources, Urmia University, Iran F. Geravandi 1003194753284600698 1003194753284600698 No Department of Biology, Islamic Azad University, Urmia Branch, Iran S. Karchin 1003194753284600699 1003194753284600699 No Department of Fisheries, Faculty of Natural Resources, Urmia University, Iran