Marine Psychrophilic Bacteria Secrete Cold-adapted Protease Enzymatic Properties And Its Stability Protection

There are various and abundant microorganisms in the sea.They are the valuable resources for the finding of new enzymes and new medicines,and have good potential for research and development in the future. Extremophiles are one of the research hot spot in the region of Microbiology. Cold-adapted microorganisms are one kind of extremophiles and are widely distributed in the sea.They are the good materials for isolation of cold-adapted enzymes. Cold-adapted enzymes are very useful in the trades,such as laundry, food,milk,medicine and cosmetics et al, which need enzymatic catalysis at low temperature,because they higher catalytic efficiency at low temperature. Therefore, cold-adapted enzymes aroused wide concern of scientists in the world.Enzymological characteristics of two phychrophilic proteases produced by two psychrophilic strain L09 and SM-9913 espectively, effects of salt and inorganic irons(Ca²⁺, Mg²⁺, Fe²⁺, Mn²⁺) on enzyme activity, as well as the protection of enzyme stability by oligosaccharides , polysaccharides, and inorganic iron were studied. The effects of instantaneous activation and inhibition on proteases activity by salt and inorganic irons with variety concentration were discussed. Meanwhile, potential applications of psychrophilic proteases and trehalose dihydrate as stabilizer of proteaseswere discussed.The result shows that psychrophilic protease produced by the strain L09 and SM-9913 had highest enzyme activity at the environment of pH 8.0, 40 °C and pH 8.5 ,35"C respectively. Both of the proteases were alkalescencal protease, 57% and 74.9% of the enzymatic activity of protease from L09 and SM-9913 lost respectively when they were incubated at 50°C for half an hour, so that protease from L09 was more stable than that from SM-9913.Two proteases were both extracelular enzyme. Their enzymatic activity were influenced by the salt concentration and ion in the sea water. The experiment results showed that the NaCl and ion of different concentration could restrain or stimulate the enzyme activity instantaneously.The protective function of trehalose, sodium alginate and Ca2+ on protease stability, which representation disaccharide, polysaccharide and ion respectively were studied, the result showed trehalose could protect the protease stability at temperature of 20 °C.