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Luminescent bacterial sensor for cadmium and lead
S Tauriainen1, M Karp, W Chang
1University of Turku, Department of Biotechnology, Finland.
Biosensors & Bioelectronics
|December 5, 1998
Summary
A novel biosensor plasmid, pTOO24, enables rapid detection of heavy metals like cadmium and lead in both Gram-positive and Gram-negative bacteria. This tool offers sensitive and efficient environmental monitoring with minimal incubation time.
Area of Science:
- Environmental microbiology
- Biosensor development
- Molecular biology
Background:
- Heavy metal contamination poses significant environmental and health risks.
- Existing heavy metal detection methods can be slow, expensive, or require specialized equipment.
- Development of rapid, sensitive, and cost-effective biosensors is crucial for environmental monitoring.
Purpose of the Study:
- To construct and characterize a novel broad-host-range sensor plasmid (pTOO24) for detecting extracellular heavy metals.
- To evaluate the performance of the pTOO24 sensor in different bacterial strains (Gram-positive and Gram-negative).
- To assess the sensitivity, specificity, and stability of the biosensor under various conditions.
Main Methods:
- Construction of a sensor plasmid (pTOO24) by inserting the cadA determinant regulation unit to control firefly luciferase expression.
- Replication of pTOO24 in Gram-positive (Staphylococcus aureus RN4220) and Gram-negative (Bacillus subtilis BR151) bacteria.
- Measurement of luminescence in response to varying concentrations of extracellular heavy metals (cadmium, lead, antimony, zinc, tin).
- Assessment of induction coefficients and effect of freeze-drying on sensor performance.
Main Results:
- The pTOO24 sensor plasmid demonstrated replication in both Gram-positive and Gram-negative bacteria.
- Staphylococcus aureus RN4220(pTOO24) showed high sensitivity to cadmium (10 nM), lead (33 nM), and antimony (1 nM).
- Bacillus subtilis BR151(pTOO24) responded to cadmium (3.3 nM), antimony (33 nM), zinc (1 µM), and tin (100 µM).
- High induction coefficients (23-50 for S. aureus, ~5 for B. subtilis) were achieved within 2-3 hours.
- Freeze-drying had minimal impact on sensor sensitivity and induction coefficients.
Conclusions:
- The pTOO24 sensor plasmid provides a sensitive and rapid platform for detecting multiple heavy metals in diverse bacterial hosts.
- This biosensor offers a valuable tool for environmental monitoring of heavy metal contamination.
- The stability of freeze-dried sensor strains suggests potential for field applications and long-term storage.