The determination of ion concentrations within cells and sub-cellular compartments remains a difficult procedure, as the volumes to be analyzed are rather small. X-ray microanalysis is sufficiently sensitive, and has adequate resolution, to measure these concentrations. The major difficulties are re
Optimal conditions for stability of photoemission and freeze drying of two luminescent bacteria for use in a biosensor
✍ Scribed by Laura Camanzi; Luca Bolelli; Elisabetta Maiolini; Stefano Girotti; Diego Matteuzzi
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 266 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0730-7268
- DOI
- 10.1002/etc.452
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✦ Synopsis
Abstract
Bioluminescent bacteria have been used for many years for biotoxicological analysis. One of the main concerns with this microorganism is the low experimental repeatability when subjected to external factors. The aim of the present study was to obtain accurate, sensitive, and repeatable measurements with stable signals (during the detection and over days) for application in a water‐analysis device for the detection of pollutants. Growth conditions were tested and optimized. An optimal freeze‐drying procedure for the constitutive bioluminescent bacteria Vibrio fischeri and Photobacterium phosphoreum was developed. The luminescence stability after rehydration was also investigated. Freeze drying was found to be a critical process in survival and signal stability of luminescent bacteria; for this reason, different suspension fluids and various bacterial pellet/suspension fluid ratios (g/ml) were evaluated. The toxicity of heavy metals and organic compounds in water was determined to investigate the applicability of a test based on bacteria obtained in this way, comparing the data with legal limits. A scale‐up process was developed with industrial technology: freeze‐dried bacteria that emitted a stable luminous signal after rehydration were obtained. Moreover, the median effective concentration (EC50) was calculated with these bacteria. Environ. Toxicol. Chem. 2011; 30:801–805. © 2010 SETAC
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