Uncovering High-Yield Ectoine Producers from Extreme Environments: Insights from Tuz Lake

Ectoine, a compatible solute produced by halophile microorganisms, is widely used in various industries due to its protective properties against environmental stress. This study aimed to isolate and characterize bacterial strains capable of producing high levels of ectoine without medium optimization from Tuz Lake, an extremely saline environment in Turkey. Bacterial isolates were obtained by selective culturing on meat peptone agar containing NaCl concentrations ranging from 3% to 21%, using water and soil samples collected from randomly selected sites in the Şereflikoçhisar and Cihanbeyli regions. A total of 22 isolates were screened for salt tolerance and their potential for ectoine production. Among them, 10 isolates with the highest salt tolerance and distinctive colony morphology were selected for further analysis. Molecular characterization via 16S rRNA sequencing identified these isolates as belonging to the genera Halomonas, Chromohalobacter, and Salinivibrio. High-performance liquid chromatography (HPLC) analysis revealed that Salinivibrio sp. (Isolate 12) and Halomonas sp. (Isolate 21) exhibited the highest ectoine production, yielding 296.88 µg mL-1 and 202.49 µg mL-1, respectively. To optimize ectoine yield, a Plackett-Burman experimental design was applied, evaluating the effects of different nitrogen sources. Peptone was identified as a statistically significant factor (p < 0.05) for enhancing ectoine production in Salinivibrio sp. This study highlights the biotechnological potential of halophilic bacteria from Tuz Lake for industrial ectoine production and emphasizes the importance of medium optimization in improving ectoine yields. Further optimization may enable the development of scalable processes for commercial ectoine production.