Effects of cadmium, copper, magnesium, and zinc on the decomposition of citrate by a Klebsiella sp.
AUTOR(ES)
Brynhildsen, L
RESUMO
The effects of Cd2+, Cu2+, Mg2+, and Zn2+ on the decomposition of citric acid by a Klebsiella sp. were studied by monitoring the degradation of [14C]citrate. The carbon concentration used was 10 micrograms of C liter-1, and the media were designed to provide at least 95% of the citrate complexed to the metal studied. After 72 h of incubation, 80% of the uncomplexed citric acid and 76% of the magnesium citrate had been decomposed. A marked inhibition was observed when Cd2+, Cu2+, or Zn2+ was bound to the organic anion; only 23% of the cadmium citrate, 14% of the zinc citrate, and 5% of the cuprous citrate had been decomposed. The effects were not the result of toxicity, since experiments run with [14C]glucose (nonchelating compound) instead of citrate resulted in similar decomposition rates regardless of the presence of the metal. To examine whether the binding of a metal to citrate enhanced its uptake by the Klebsiella sp., we studied the relative uptake of 65Zn in citrate- and in glucose-containing media. No such effect could be observed, with the uptake of Zn2+ being higher in the glucose-containing media. The study shows that metals may render low-molecular-weight organic acids, such as citric acid, resistant to bacterial degradation. This stresses the importance of metals in influencing microbial decomposition of organic compounds, not only as a result of toxicity.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=202874Documentos Relacionados
- Effects of Glucose Concentrations on Cadmium, Copper, Mercury, and Zinc Toxicity to a Klebsiella sp
- Levels of Chromium, Copper, Iron, Magnesium, Manganese, Selenium, Zinc, Cadmium, Lead and Aluminium of honey varieties produced in Turkey
- Tolerance to and Accumulation of Cadmium, Copper, and Zinc by Cupriavidus necator
- Localization and Toxic Effects of Cadmium, Copper, and Uranium in Azolla1
- Spectrochemical Analysis of Sodium, Potassium, Calcium, Magnesium, Copper, and Zinc in Normal Human Erythrocytes*