Studies On Degradative Pathway Of 3-hydroxybenzoate In Pseudomonas Putida ZWL73

Pseudomonas putida ZWL73,which completely degrades 4-chloronitrobenzene (4-CNB), can grow on 3-hydroxybenzoate (3-HBA) as a sole carbon source and energy source. During the course of the degradation of 3-HBA, gentisate was produced as an intermediate. Through spectrophotometric analyses on cell extracts of ZWL73 induced with 3-HBA, it was indicated that glutathione(GSH)-dependent gentisate pathway is involved in the 3-HBA catabolism in ZWL73 and the catabolism of this pathway needs to be induced with 3-HBA or gentisate. The gene encoding 3-HBA-6-monooxygenase, which converts 3-HBA to gentisate, was cloned and functionally expressed. Comparison analyses on the sequences of 3-HBA-6-monooxygenases from ZWL73 and Klebsiella pneumoniae M5a1 show a high similarity. In addition, ZWL73 can also utilize gentisate, catechol, protocatechuate, 4-hydroxybenzoate, etc, as a sole carbon source and energy source. Cell extracts from ZWL73 induced with different growth substrates showed evident catalytic activity.