Abstract
The occurrences of mercury-resistant bacteria in relation to mercury chloride, methylmercury chloride and phenylmercuric acetate was examined, using various strains isolated from the Minamata Bay, as well as from control sediments with low levels of mercury. Minimal inhibitory concentra-tions (MICs) to mercury chloride were significantly higher for the Pseudomonas sp. (p<0.01, Mentel-Cox test) and Bacillus sp. (p<0.05) from the Bay sediments than for those from the con-trol sediments. The MICs to methylmercury chloride were likewise higher for the Bacillus sp. (p<0.01) from the Bay sediments, and so were the MICs to phenylmercuric acetate for the Pseudomonas sp. '(p<0.001) from the Bay sediments than for those from the control sediments. The percentage of highly mercury-resistant bacteria belonging to various bacterial genera increased with the concentration of mercury in the sediments. On the other hand, mercury-sensitive Pseudo-monas Bacillus and Corynebacterium sp. were also observed in the Minamata Bay sediments.
