Inhibition of bacterial growth by mercury and the effects of protective agents

Twenty-two bacterial cultures were isolated from sediment samples, characterized morphologically and biochemically, and tested for resistance to mercury. Of all the cultures examined only two obligate anaerobes, Bacteroides and a Clostridium were found to be sensitive to very low levels of mercury. Both the Bacteriodes and Clostridium were inhibited by 1.1 /sup +/g mercury or more per disc. In the presence of the same level of mercury and at a cell concentration of 10 CFU per ml of medium, the inhibition zones were greater for the Bacteriodes than for the Clostridium. Maximum protection of the entire cell population was noted against 5.0 ..mu..g Hg/ml when the buffer had 5.0 mg of sediment. The surviving fraction in the presence of 2.5 mg of sediment and 2.5 ..mu..g of mercury remained fairly constant (0.81) during the entire 15 minute exposure, indicating that this level of sediment completely protected the entire cell population against the bactericidal action of that level of mercury. 21 references, 2 figures, 1 table.