The Effect of Some Factors of Polluted Environment on Catalase Responses and Resistance of Microbial Isolates Against Toxic Oxidative Stress

Abstract

The properties of bacterial isolates from polluted environments which are characterized by increased levels of oxidative stress do not reflect only the level of contaminants, but also arise as a consequence of many permanently changed conditions. The survival rate of Comamonas terrigena N3H isolates from an environment with elevated levels of H(2)O(2) is correlated with stimulation of catalase. The response of bacterial catalase to the effect of phenol in exogenous conditions was affected by the presence of an additional contaminant, Cd(2+). An isolate of Aspergillus niger selected from river sediment containing 363mg/kg As, 93mg/kg Sb at pH 5.2-4.8 grew on Czapek-Dox agar ~1.6 times faster than an isolate of the same species from coal dust sediment with approximately the same level of pollution (400mg/kg As) but somewhat lower pH (3.3-2.8). It also exhibited differences in the microscopic characteristics of its mycelial structures. Both isolates exhibited a higher tolerance to the exogenic toxic effects of metals (As(5+), Cd(2+), and Cu(2+) at 5, 25, or 50mg/L) than a control culture, but the differences in tolerance between them were only slight. These laboratory results suggest that there are complicated relationships which may exist in the "in situ" environment.