Stability of the halophilic enzyme d -2-hydroxyacid dehydrogenase from H. mediterranei under different conditions and media

The halophilic enzyme d-2-hydroxyacid dehydrogenase from Haloferax mediterranei catalyses the production of d-2-hydroxy acids, which are important in industry. In order to use an enzyme in industry, it is essential to know its stability under several conditions and media. The stability of this enzyme has been analysed at different temperatures and pH levels and in different organic/aqueous media such as ethanol, glycerol and DMSO. According to the results obtained, the halophilic enzyme exhibits the best stability in 4 M NaCl and 3 M KCl, with half-lives of 125 and 14 days, respectively. The enzyme has a slightly thermophilic character, showing half-life values of 3.5 days and 13 h at 50 °C and 60 °C, respectively. Concerning organic solvents, the maximum stability was observed in 30% glycerol, retaining 50% of its activity after 58 h, making it a potentially robust enzyme for industrial use.