Interaction of Heavy Metals with Aerobic Soil Bacteria

The fate of metals in the environment can be influenced by interaction with bacteria. This research focused on the interactions of metals and common soil bacteria, with emphasis on cadmium and Pseudomonas mendocina. P. mendocina was chosen because it is a metal resistant aerobic bacterium that has been used for bioremediation purposes. Cadmium was chosen because it is a common environmental contaminant of widespread ecological consequence. This study used batch experiments with microscopic and spectroscopic techniques. Typical batch bacterial growth curves were observed. Cadmium was found to delay the onset of exponential growth phase and decrease maximum population size. The amount of cadmium removed from solution increased over time both in total and on a per-cell basis. TEM showed the formation of cell-associated precipitates that redissolved by death phase, while EXAFS indicated a cadmium-sulfide bonding character that increased over time and was not present in washed cells.