Toxicity of chlorobenzenes to a lux-marked terrestrial bacterium, Pseudomonas fluorescens

Elaine M. Boyd, Andrew A Meharg, Julian Wright, Ken Killham

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Abstract

Insertion of lux genes, encoding for bioluminescence in naturally bioluminescent marine bacteria, into the genome of Pseudomonas fluorescens resulted in a bioluminescent strain of this terrestrial bacterium. The lux-marked bacterium was used to toxicity test the chlorobenzene series. By correlating chlorobenzenes 50% effective concentration (EC50) values against physiochemical parameters, the physiochemical properties of chlorobenzenes that elicit toxic responses were investigated. The results showed that the more chlorinated the compounds, the more toxic they were to lux-marked P. fluorescens. Furthermore, it was shown that the more symmetrical the compound, the greater its toxicity to P, fluorescens. In general, the toxicity of a chlorobenzene was inversely proportional to its solubility (S) and directly proportional to its lipophilicity (K-ow). By correlating lux-marked P. fluorescens EC50 values, determined for chlorobenzenes, with toxicity values determined using Pimephales promelas (fathead minnow). Cyclotella meneghiniana (diatom), and Vibrio fischeri (marine bacterium), it was apparent that lux-marked P. fluorescens correlated well with freshwater species such as the diatoms and fathead minnow but not with the bioluminescent marine bacterium V. fischeri. The implications of these findings are that a terrestrial bacterium such as P. fluorescens should be used for toxicity testing of soils and freshwaters rather than the marine bacterium V. fischeri.

Original languageEnglish
Pages (from-to)2134-2140
Number of pages7
JournalEnvironmental Toxicology and Chemistry
Volume17
Issue number11
DOIs
Publication statusPublished - Nov 1998

Keywords

  • chlorobenzenes
  • lux
  • QSARs
  • soil bacterium
  • Pseudomonas fluorescens
  • classifying environmental-pollutants
  • quantitative structure
  • chemical descriptors
  • soil
  • uncouplers
  • systems
  • tests
  • acid

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