Study of the effect of cadmium on the activity of protease of Pseudomonas aeruginosa

Cadmium is a heavy metal used in industry. This metal enters water and soil through factory effluents and causes environmental pollution and thus affects the growth of plants and microorganisms. Cadmium can disrupt metabolism by affecting cellular enzymes. Pseudomonas aeruginosa is a soil bacterium that is involved in the removal of hydrocarbon contaminants such as oil and industrial effluents. Infiltration of cadmium along with industrial effluents can affect the ability of this bacterium to remove contaminants. In this study, the effect of the presence of cadmium on the growth of P. aeruginosa and its effect on protease activity were studied. The results showed that the presence of cadmium in the culture medium reduced the biomass and decreased the activity of protease secreted in the medium. The effect of the presence of different sources of nitrogen to activate protease secretion in the culture medium was investigated and it was found that nutrient broth has the highest effect on activating protease. The effect of different concentrations of cadmium on the extracted protease showed that cadmium can reduce the activity of the extracted enzyme. The value of IC50 was estimated to be about 0.1 mM. The optimum pH and temperature of the enzyme were 9 and 40oC, respectively, which the presence of cadmium reduced the enzyme activity at this pH and temperature. Finally, the results showed that the presence of cadmium can not only affect the growth of bacteria, but also reduce the activity of protease