Sensitivity of Various Bacteria, Including Actinomycetes, and Fungi to Cadmium and the Influence of pH on Sensitivity.

A variety of microorganisms, including gram-negative and gram-positive eubacteria, actinomycetes, yeasts, and filamentous fungi, were tested for their sensitivity to cadmium (Cd). In general, the actinomycetes were more tolerant to Cd than were the eubacteria; gram-negative eubacteria were more tolerant to Cd than were gram-positive eubacteria. The period of exponential growth of the eubacteria and actinomycetes was extended in the presence of Cd. Wide extremes in sensitivity to Cd were noted among the fungi; there was no correlation between the class of fungus and tolerance to Cd. Fungal sporulation was more sensitive to Cd than was mycelial growth, as spore formation was inhibited at Cd concentrations that were noninhibitory to mycelial proliferation. The toxicity of Cd to the eubacteria, actinomycetes, and fungi appeared to be pH dependent, as toxicity was generally potentiated at pH 8 or 9.