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

Photobacterium phosphoreum

Luminescent bacteria

Pellet

Suspension

Bioreporter

10.1002/etc.452

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Bioluminescent flow-sensing device for the determination of magnesium (II)

The Analyst (1993)

Stefano Girotti Elida Nora Ferri Severino Ghini Pavel Rauch Giacomo Carrea

A continuous-flow system was developed for the assay of magnesium(II) in serum, drugs and beverages, making use of firefly luciferase (LUC)(EC 1.13.12.7) or recombinant luciferase (r-LUC) from Escherichia coli immobilized on a nylon coil or a column of epoxy methacrylate (Eupergit) placed inside a luminometer. The flow was air segmented and 10 µl samples were analysed. The sample assay rate was 20 h–1 with no carryover. The optimum operational conditions were found to be 0.05 mmol l–1 luciferin and 0.3 mmol l–1 ATP (adenosine triphosphate) at a flow rate of 0.4 ml min–1. The detection limit of the assay was 0.05 mmol l–1 for an LUC—nylon coil and 0.01 mmol l–1 for an LUC-Eupergit column or an r-LUC—nylon coil and the response was linear from 0.05 to 6.7 and from 0.01 to 6.7 mmol l–1, respectively. Both the intra- and inter-assay relative standard deviations were lower than 7%. No interferences from ions present in the samples (Ca2+, Mn2+, Fe2+, Cu2+, Zn2+, Co2+) were found. Results obtained for serum by the present method were in good agreement with those given by spectrophotometry with Xylidyl Blue II and by atomic absorption spectrometry.

Spectrophotometry

Flow injection analysis

10.1039/an9931800849

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Citations (10)