Isolation，identification and characterization of an agaraseproducing marine bacterial strain Stenotrophomonas sp. NTa

Abstract:

Abstract: ［Objective］To identify and characterize a marine bacterial strain producing agarase．［Methods］The agaraseproducing bacterium was isolated from coastal sediments in Xiamen using agar as the sole carbon source．The strain was identified by the analyses of 16S rＲNA gene sequence，phenotype and biochemical reactions．Agarase activity was determined by dinitrosalicylic acid method，and the category of agarase was assayed using chromogenic substrate．At last，the characteristics of agarase were determined．［Results］ The results of the 16S rRNA phylogenetic，phenotypic and biochemical analyses showed that: the agar-degrading bacterium NTa belonged to the genus Stenotrophomonas sp. The strain could produce extracellular agarases，including α-agarase and β-agarase．The optimum temperature and pH of strain NTa agarase were 40℃ and 7.0，respectively．The enzymatic activity was stable below 30℃．It also showed stability over a pH range between 7.0 and．0.Ca2+ could activate agarase activity，and Na+，K+ and Mg2+ had no significant influence．However，Ag+，Ba2+，Fe2+，Mn2+，Cu2+，Zn2+ and Fe3+ inhibited the enzyme activity．The enzymatic activity of stain NTa agarase was inhibited by EDTA．The agarase had good resistance to some inhibitors，detergents and denaturant.［Conclusion］ Stenotrophomonas sp. NTa is a new type of agarase-producing strain，which can produce both α-agarase and β-agarase and has potential applications in the production of agaro-oligosaccharide．

Key words:Keywords:Stenotrophomonas sp.，agarase，identification，characterization