Isolation, Identification And Extracellular Protease Characteristic Of Halomonas Sp. SD-01

One Gram-negative bacterial strain was isolated from saline soda lake in InnerMongolia. Based on polyphasic studies, including its morphology, physiological andbiochemical characteristics, chemotaxonomy and 16SrDNA sequence analysis, it wasa new species of genus Halomonas and nomeneultured it as Halomonas sp. SD-01.The Halomonas sp. SD-01 was Psychrotrophilic and excreted psychrophilicprotease. The optimum temperature for growth was about 15℃,and the highesttemperature for growth was 35℃.The highest specific synthetic rate of the proteaseoccurred at about 10℃.The optimum tempature of the protease activity for casincatalysis was about 35℃ and even at 0℃it still remain little protease activity forcasin catalysis,the optimum pH of the protease activity for casin catalysis was about10.0,which suggested the enzyme was a typical alkaline psychrophilic protease.The protease was purified from the cell-free supernatant by ammonium sulfateprecipitation, ion exchange chromatography and gel filtration chromatography.SDS-PAGE analyses revealed a single band of 69.2 Kda.The protease activity wasstimulated by Mn²⁺, Cu²⁺, and was inhibited by Ag⁺, Al³⁺, Hg²⁺. From the result thatEDTA showed obvious inhibiting effect on the enzyme, it can be suggested that metalions played an important role in the conservation of enzyme conformation for thecatalytic activity.