Identification of halophilic archaea producing protease from Yipinglang salt mine and its enzymatic properties

Haloarchaeal strains isolated from Yipinglang salt mine were screened for extracellular protease production.Their enzyme properties were studied.The results showed that YPL20 and YPL26 showed the highest protease activity, and were identified as Halococcus salifodinae strains.The maximal protease activity of YPL20 occurred at 50℃, p H9.0, and 0 mol/L Na Cl.The YPL26 protease exhibited optimal activity at 50℃, p H7.0⁹.0, and 2.5 mol/L Na Cl.The YPL20 and YPL26proteases were highly stable over wide ranges of temperatures, p H values and Na Cl concentrations.Mn²⁺and Ca²⁺significantly enhanced protease activity of YPL20 and YPL26.Cu²⁺and Zn²⁺significantly inhibited the protease activities.The protease activities were completely inhibited by serine protease inhibitor, indicating that YPL20 and YPL26 proteases may be serine proteases.