PROTEIN-PRODUCTION DURING HEAT-STRESS AND EXPOSURE TO TOXICANTS IN ALCALIGENES-EUTROPHUS JMP228

In an effort to determine whether heat-shock proteins might serve as useful indicators of environmental stress, the aquatic bacterium, Alcaligenes eutrophus JMP228, was exposed to two chemical stressors: a toxic heavy metal ion, cadmium, and a nonbiodegradable organic herbicide, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Protein synthesis was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, comparing the protein patterns of chemically stressed cells to those exhibited by nontreated and heat-shocked cells. Heat-shock proteins were produced in response to both chemical stressors and heat. Proteins induced in response to all three experimental stresses include molecules with approximate molecular weights of 58-60 and 106 kDa. Still other stress proteins were only expressed following chemical stress. A 106 kDa protein was only produced following cadmium treatment, whereas proteins of 37, 39, 46, 49, and 77 kDa were only produced in response to 2,4,5-T. The synthesis of some of the unique stress proteins varied in a dose-dependent fashion with the concentration of the individual stressors. The presence of these proteins may be useful indicators of the ''health'' of an environment.