Kluyvera ascorbata SUD165 and a siderophore-overproducing mutant of this bacterium, K. ascorbata SUD165/26, were used to inoculate tomato, canola, and Indian mustard seeds which were then grown in soil for 25-42 days in the presence of either nickel, lead, or zinc. The parameters that were monitored included plant wet and dry weight, protein and chlorophyll content in the plant leaves, and concentration of heavy metal in the plant roots and shoots. As indicated by a decrease in the measured values of these parameters, in all instances, plant growth was inhibited by the presence of the added metal. Both bacterial strains were effective, although not always to a statistically significant extent, at relieving a portion of the growth inhibition caused by the metals. In most cases, the siderophore overproducing mutant K. ascorbata 165/26 exerted a more pronounced effect on plant growth than did the wild-type bacterium K. ascorbata SUD165. The data suggest that the ability of these bacteria to protect plants against the inhibitory effects of high concentrations of nickel, lead, and zinc is related to the bacteria providing the plants with sufficient iron.

Cyanide markedly affected growth and resting metabolic rate while causing degenerative hepatic necrosis in juvenile rainbow trout (Salmo gairdneri, Richardson). This was revealed during two experiments performed in continuously renewed water at 12.5 degree C with fish fed a restricted artificial diet and exposed to assayed cyanide concentrations of 0.00, 0.01, 0.02, or 0.03 mg/L hydrogen cyanide (HCN) for 18 days. At 0.02 and 0.03 mg/L, HCN growth was reduced by 40 to 95% after 18 days. At all concentrations, cyanide caused a severe initial repression of specific growth rate, followed by a highly significant increase which was insufficient to compensate for the original repression. Previous exposure to cyanide promoted a higher resting metabolic rate during the six days following exposure, the effect increasing with cyanide concentration. At all concentrations tested, widespread cyanide-induced degenerative necrosis of hepatocytes was observed; it was more intense at higher cyanide concentrations and well established even at 0.01 mg/L HCN.

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