Journal of Microbiology

Production of Stress-shock Proteins in Pseudomonas sp. DJ-12 Treated with 4-Hydroxybenzoate: Park, Sang Ho , Oh, Kye Heon , Lee, Kil Jae , Kim, Chi Kyung; J. Microbiol. 1998;36(4):273-279.

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.

Synthesis and Requirement of Escherichia coli Heat Shock Proteins GroEL and DnaK for Survival under Phenol Stress Conditions: Jeon, Taeck Joong , Lee, Kil Jae; J. Microbiol. 1998;36(1):26-33.

Abstract: Exposure of Escherichia coli strain MC4100 to various concentrations of phenol at temperatures higher than 20℃ led to induction of stress proteins such as GroEL and DnaK, as analyzed by SDS-PAGE and Western blotting methods. The optimum range of phenol concentration for the induction of GroEL and DnaK was slightly different at each temperature of bacterial growth and phenol treatment. The level of GroEL increased as the temperatures of growth and phenol treatment were increased from 30℃ to 40℃. The level of induced FroEL was maximal in the wild type cells which had been grown and treated by 2000㎍/㎖ phenol at 40℃. In contrast to GroEL, the level of DnaK decreased as the temperatures of growth and phenol treatment were increased from 25℃ to 40℃. Dnak was maximally induced in the cells grown and exposed to 1000㎍/㎖ phenol at 25℃. In rpoH mutant cells KY1601, GroEL was not additionally induced by phenol treatment and DnaK was not even detectable under normal and phenol stress conditions. Viability of cells under the same conditions of phenol treatment showed that the phenol resistance in much more induced in wild type cells than rpoH mutant cells. These results suggest that the induction of GroEL and DnaK is required for the enhanced viability of cells under conditions of phenol stress.

Cellular Response of Pseudomonas sp. DJ-12 to the Stresses of Several Aromatic Pollutants: Park, Sang Ho , Ko, Yeon Ja , Oh, Kye Heon , Kim, Chi Kyung; J. Microbiol. 1998;36(2):93-98.

Abstract: Pseudomonas sp. DJ-12 is capable of degrading biphenyl, 4-chlorobiphenyl (4CB), and 4-hydroxybenzoate (4HBA) at relatively low concentrations. The degradability and cellular responses of the organism to the aromatic pollutants at higher concentrations have not been studied. In this study, the survival of the cells, production of stress proteins, and induction of tolerance were examined by exposing cells to various concentrations of the aromatics. The survival rates of the organism were reversely proportional to the concentration of each aromatic during incubation for 6 hs. Stress protein specifically reacting with anti-DnaK monoclonal antibody was commonly produced when cells were treated with each aromatic. Those cells pretreated with each aromatic at lower concentrations exhibited a certain degree of tolerance to higher concentrations of the aromatics. Such cellular responses of the organism to water-soluble 4HBA were more clearly distinguished than those to insoluble 3CB and biphenyl. Therefor, induction of DnaK stress protein in the cells by exposure to the aromatiocs could be used to develop an indicator for pollution by the aromatics.

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