Characterization of salicylate 5-hydroxylase for phenanthrene degradation using moderately halophilic Martelella sp．AD-3

Abstract:

Abstract:［Objective］To identify the relationship between salicylate 5-hydroxylase activity and the degradation rate of phenanthrene by moderately halophilic Martelella sp． AD-3， and to investigate their enzymatic characteristics．［Methods］ The products resulted from degradation of salicylic acid using the crude enzyme produced by AD-3 was analyzed using HPLC analysis，and salicylate 5-hydroxylase activities at different conditions was calculated according to the change of NADH absorbance at 340 nm． ［Results］The salicylate 5-hydroxylase activity was higher during log-phase and early stationary phase of AD-3，and the enzyme activity was in consistent with phenanthrene degradation rate． The enzyme production was induced by phenanthrene and salicylic acid． The highest enzyme activity，132.8 nmol/(min·mg)，from strain AD-3 was obtained under the phenanthrene concentration of 200 mg/L，3% salinity and a pH of 9.0．The optimum conditions for degradation of salicylic acid using this enzyme were 30℃，pH 7.5，and salinity 3%．The Vmax and Km for the enzyme were 200 nmol/(min·mg) and 8.7μmol/L，respectively．［Conclusion］The salicylate 5-hydroxylase was produced in the degradation of phenanthrene in AD-3． The enzyme activity was related to phenanthrene degradation rate．

Key words:Keywords: phenanthrene，salicylate 5-hydroxylase，enzyme activity，salinity