Investigation of extracellular protease activity of two different extremely halophilic archaea isolated from raw hide

In this study, it was aimed to investigate extracellular protease activity of two diff erent extremely halophilic archaea and to identify them by using phenotypic and molecular methods. The haloarchaea were isolated from salted raw hide. The isolates were screened for production of protease enzyme and two isolates which have extracellular protease activity were selected. To identify the halophilic archaea, Gram staining procedure, antibiotic sensitivity tests and molecular methods were used. According to the 16S r-RNA molecular identifi cation results, isolate 1 identifi ed as Halococcus morrhuae JCM 8876 with % 99 sequence similarities and isolate 2 identifi ed as Natrinema pallidum 153 with % 99 sequence similarities. Azocasein was used as a substrate for measuring their proteases activities daily and their optimum activities were determined. H. morrhuae and N. pallidum showed daily maximum proteases activity on 6 and 4 days, respectively. According to the results of the study, it was found that proteases activity was related with diff erent reaction conditions. These conditions were detected as diff erent pH (4-11), temperature (4-70°C) and NaCl concentration (1-5 M) values. H. morrhuae showed the maximum activity at pH 9.5, 2M NaCl concentration and 50°C temperature and N. pallidum displayed the optimum activity at pH 9.0, 2M NaCl concentration and 40°C temperature.