Interactions between soil, toxicant, and a lux-marked bacterium during solid phase-contact toxicity testing

Liz J. Shaw*, Yvonne Beaton, L. Anne Glover, Kenneth Killham, Andrew A. Meharg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Bioluminescence-based, solid-contact toxicity assays allow test bacterium and toxicant to interact at the solid-solution interface. A lux- marked bacterium, Burkholderia sp. RASC, and 2,4-dichlorophenol (2,4-DCP) were used to characterize these interactions. In the basic bioassay, cells were added to soil slurries containing 2,4-DCP (0-120 μg ml-1). After 15 min, soil was removed by centrifugation, and bioluminescence in the supernatant was determined. Investigation of 2,4-DCP adsorption to soil revealed that sorption was linear and not significantly (p > 0.1) affected by the presence of Burkholderia cells. The numbers of culturable Burkholderia cells in the assay supernatant were 48.2 to 64.8% of the inoculum and independent of the soil weight. The effect of soil on 2,4-DCP toxicity was investigated by comparing soil aqueous extract and contact assays. The percentage bioluminescence for the contact assay was consistently higher than the extract assay at all test concentrations, and counts of viable Burkholderia cells were enhanced by the presence of 2,4-DCP in the contact assay. Expressing results as specific bioluminescence decreased the variability in response and the discrepancy in results between the two protocols. We suggest that solid-contact assays need improvement to ensure defined contact between cells and solid phase, and that the reporting of specific activity should be emphasized.

Original languageEnglish
Pages (from-to)1247-1252
Number of pages6
JournalEnvironmental toxicology and chemistry
Volume19
Issue number5
Publication statusPublished - 2000

Keywords

  • 2,4-Dichlorophenol
  • Bioassay
  • Soil lux
  • Toxicity

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Toxicology
  • Health, Toxicology and Mutagenesis

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