Isolation and characterization of chemolithotroph bacteria in urmia lake and investigation of antibiotic properties & reduction of metals

Abstract

Background: Due to the last two decades of drought disaster, which resulted in the loss of the main part of Urmia Lake water and changed the natural conditions of an environment, especially ionic strength. Objective: We aimed to isolate and characterize halophilic and halotolerant bacteria in Urmia Lake, Iran, 2015. Urmia Lake is a permanent and salty inland lake located in the Azerbaijan region in northwestern Iran. Method: Sampling was carried out in multiple water-filled locations of the lake. Liquid basal media for the enrichment of bacteria was successively applied The growth rate during enrichment was usually checked by increase in the turbidity and decrease in the pH value. Once the pH was decreased, we sufficiently added NaHCO3 solution in order to return the pH value to 7. colonies were isolated by the plating method after several subculturing. Isolates were then distinguished based on differences in colony, Gram staining, microscopic shape, phylogenetic and biochemical properties. Results: Only one isolate (TBZ201) was obtained from EM-1 with 0% NaCl which belongs to Thiobacillus genus as chemolitotrophic bacteria and 41 heterotrophic isolates were obtained. The 16S rRNA gene sequences showed that all 42 isolates belong to the genera Kocuria (21.42%), Marinobacter (11.90%), Micrococcus (11.90%), Thalassobacillus (11.90%), Bacillus (11.90%), Halomonas (7.14%) and Thiobacillus (2.38%). Conclusion: Based on 16S rRNA similarity, 4 of 42 isolates showed the potential to be introduced as new species. The dominant genera with abounded frequency were found to be Kocuria, Bacillus and Thalassobacillus genera.