Abstract

Pseudomonas sp. DJ-12 can grow on 4-hydroxybenzoate (4HBA) at concentration of 5 mM or lower by degrading 4HBA for carbon and energy sources. The organisms were found to produce DnaK stress-shock protein when treated with several aromatic hydrocarbons including 4HBA. Those cells treated with 5 mM 4HBA exhibited increased tolerance to 10 mM concentration. In this study, the production of other stress-shock kproteins besides KnaK was examined in Pseudomonas sp. DJ-12 exposed to various concentrations of 4HBA, compraing the production of the proteins with their survival and degradation of 4HBA. The organisms could degrade 4HBA at 0.5 to 5 mM concentrations after 60 to 90 minutes of incubation. The survival rate of the organism decreased when treated with 4HBA at 10 mM or higher concentrations. The stress-shock proteins of DnaK, GroEL, and GroES were produced in the cells which were treated with 4HBA at 0.5 mM or higher concentrations for 10 minutes. Fifteen additional stress-shock proteins were produced in the cells which were treated with 5 mM 4HBA for 40 minutes. The DnaK and GroEL proteins in the cells gradually decreased upto 6 hours after the stress was removed from the culture.

• Keywords: Stress-shock proteinsm; DnaK; GroEL; 4HBA stress; Pseudomonas sp. DJ-12