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Mercury uptake and removal by Euglena gracilis.
S Devars1, C Avilés, C Cervantes
1Departamento de Bioquímica, Instituto Nacional de Cardiología, México. sdevars@hotmail.com
Archives of Microbiology
|October 21, 2000
Summary
Euglena gracilis tolerates mercury by maintaining low intracellular levels and high glutathione, not through volatilization. Dark conditions increased mercury uptake but decreased glutathione, hindering tolerance.
Area of Science:
- Environmental Microbiology
- Biochemistry
- Ecotoxicology
Background:
- Mercury is a toxic heavy metal pollutant.
- Microorganisms play a role in mercury cycling and remediation.
- Euglena gracilis is a freshwater protist with potential bioremediation capabilities.
Purpose of the Study:
- To investigate mercury (HgCl2) uptake and removal mechanisms in Euglena gracilis.
- To assess the role of light and glutathione in mercury tolerance.
- To determine if mercury volatilization is an effective resistance strategy.
Main Methods:
- Culturing Euglena gracilis in media with added mercury chloride (HgCl2).
- Comparing mercury accumulation, volatilization, and cell growth under light and dark conditions.
- Quantifying intracellular glutathione levels.
Main Results:
- Light-grown cells accumulated 5-13% of mercury; dark-grown cells showed 2-3 times higher uptake.
- Mercury volatilization occurred both biologically and non-biologically, independent of light.
- Cell growth was inhibited in light; negligible in dark. Glutathione levels were higher (3.2 nmol/10^6 cells) in light and lower (1.4 nmol/10^6 cells) in dark.
Conclusions:
- Mercury volatilization by Euglena gracilis is not an effective resistance mechanism.
- High intracellular glutathione levels and low mercury uptake are crucial for successful mercury tolerance in Euglena gracilis.
- Environmental factors like light significantly influence mercury-microbe interactions and tolerance strategies.