Comparisons of Characteristics of Cadmium-Tolerant Bacterium, Pseudomonas aeruginosa G-l and Its Cadmium-Sensitive Mutant Strain

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A cadmium-sensitive mutant strain was isolated from a Cd²⁺-tolerant bacterium, Pseudomonas aeruginosa G-1 strain by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. The Cd²⁺-sensitive mutant strain was about 8-times as sensitive to Cd²⁺ and 2-times as sensitive to Hg²⁺, Cr²⁺ and achromycin, and not sensitive to Cu²⁺, as the parent strain.
Vacuole-like substances were observed in the parent strain by transmission electron microscope in the presence of Cd²⁺, but not in the absence of Cd²⁺. The mutant strain took up 3.3-times the amount of Cd²⁺ into cells when compared with the parent strain. Disc electrophoretic patterns showed a characteristic protein band in the parent strain at the stationary phase, but the corresponding protein band was present in the mutant strain at the late exponen-tial phase.