Detoxification of mercury, cadmium, and lead in Klebsiella aerogenes NCTC 418 growing in continuous culture
Klebsiella aerogenes NCTC 418 growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture exhibited sulfide formation and P/sub i/ accumulation as the only demonstrable detoxification mechanisms. In the presence of mercury under similar conditions only HgS formation could be confirmed, by an increased sensitivity to mercury under sulfate-limited conditions, among others. The fact that the cells were most sensitive to cadmium under conditions of phosphate limitation and most sensitive to mercury under conditions of sulfate limitation led to the hypothesis that these inorganic detoxification mechanisms generally depended on a kind of facilitated precipitation. The process was coined thus because heavy metals were probably accumulated and precipitated near the cell perimeter due to the relatively high local concentrations of sulfide and phosphate there. Depending on the growth-limiting nutrient, mercury proved to be 25-fold (phosphate limitation), 75-fold (glycerol limitation), or 150-fold (sulfate limitation) more toxic than cadmium to this organism. In the presence of lead, PbS formation was suggested. since no other detoxification mechanisms were detected, for example, rendering heavy metal ions innocuous as metallo-organic compounds, it was concluded that formation of heavy metal precipitates is crucially important to this organism. In addition, it was observed that several components of a defined mineral medium were able to reduce mercuric ions to elemental mercury. This abiotic mercury volatilization was studied in detail, and its general and environmental implications are discussed.
- Research Organization:
- Vrije Universiteit, Amsterdam, Netherlands
- OSTI ID:
- 5576092
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 50:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CADMIUM
DETOXIFICATION
KLEBSIELLA
SENSITIVITY
LEAD
MERCURY
BIOLOGICAL PATHWAYS
CONTINUOUS CULTURE
GLUCOSE
GROWTH
PHOSPHATES
SULFATES
ALDEHYDES
BACTERIA
CARBOHYDRATES
ELEMENTS
HEXOSES
METALS
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
SACCHARIDES
SULFUR COMPOUNDS
560302* - Chemicals Metabolism & Toxicology- Microorganisms- (-1987)