Characterization of salicylate 5-hydroxylase for phenanthrene degradation using moderately halophilic Martelella sp. AD-3
中度嗜盐菌Martelella sp. AD-3 降解菲过程中水杨酸-5-羟化酶的酶学性质

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 8.7 μmol/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.