Effects of Glucose Concentrations on Cadmium, Copper, Mercury, and Zinc Toxicity to a Klebsiella sp

Abstract

The influence of glucose concentration on Cd, Cu, Hg, and Zn toxicity to a Klebsiella sp. was studied by following the degradation of 14C-labeled glucose at pH 6.0. Uptake of '4C into the cells was also determined. The carbon concentrations ranged from 0.01 to 40 mg liter-', which are equivalent to soluble C concentrations in natural environments. The toxicity of Cu, Cd, and Zn to a KlebsieUa sp. was affected considerably by the C concentration. Copper at 10-s M was toxic when the carbon concentration was 10 or 40 mg liter-', while at 0.01 to 1.0 mg liter-' no toxicity was observed. Cadmium and zinc were toxic at 10-2 M in media containing 0.01 to 1.0 mg of C liter-'. At C concentrations greater than 1.0 mg liter-', the inhibition of glucose degradation and carbon assimilation was observed at 10-3 M Cd and Zn. The toxicity of mercury seemed to be independent of the C concentration. Results of this study showed that the nutritional state of an organism may have a profound effect on its sensitivity to metals. Metals taken up by an energy-driven transport system may be less toxic under conditions of C starvation. The C concentration should be taken into account when evaluating results from toxicity studies, especially as most microorganisms in nature live under energy-limited conditions.

Effects of cadmium, copper, magnesium, and zinc on the decomposition of citrate by a Klebsiella sp

“…Hence, the differences in citrate decomposition rates for the metal complexes were not a result of toxicity. The toxicity of Cd2+, Cu2+, and Zn2+ to the Klebsiella strain has been determined in a separate study (7), and those results indicate that the metal concentrations used in the present study were nontoxic.…”

“…About the same amount (50 to 60%) of the glucose added was also decomposed in the medium without any of the metals, whereas decomposition in the presence of Cd2+ was somewhat retarded. A great deal of the remaining 14C in the medium was probably immobilized by the cells (7). Hence, the differences in citrate decomposition rates for the metal complexes were not a result of toxicity.…”

“…The Klebsiella sp. was grown in citrate enrichment medium at room temperature for 24 h. The medium composition was described previously (7). The cells were harvested by centrifugation (6,000 x g for 10 min at 4°C) at late exponential phase and washed in 0.1 M KCl.…”

Trends and prospects for developing of new industrial biotechnologies on the base of Antarctic extremophilic microorganisns

“…металлов (Hg , Cu и др.) находятся в пределах 5-10 мг-ионов/л [4,11]. Так как Антарктика -это экологически чистая зона One of stages of such analysis is a qualitative and quantitative count of microorganisms.…”

“…В вариантах 3х10 , 5х10 , 6х10 -в среду внесена глюкоза (20 г/л). 4 4 . The most significant results on the second order plural metal resistance were obtained on media containing a mix of three metals (Tab.…”