Biosensing the acute toxicity of metal interactions: Are they additive, synergistic, or antagonistic?

Abstract

The toxicity of Zn, Cu, and Cd, alone or in combination, was assessed using two luminescence‐based microbialbiosensors from different ecological niches: Escherichia coli HB101 pUCD607 and Pseudomonas fluorescens 10586 pUCD607. Significant synergistic interactions occurred between the toxic effects of the Zn and Cu and Zn and Cd combinations and the response of E. coli (i.e., toxicities of combinations of pollutants were greater than predicted from addition of individual toxicities). Significant synergistic interactions were also observed between the toxicities of Cd and Cu combinations and the response of P. fluorescens. A longer exposure time was shown to significantly increase the sensitivity of E. coli to the metal pollutants. P. fluorescens was observed to significantly decrease in its sensitivity toward Zn and Cd with a longer exposure time. It was shown that the toxicity of combinations of metals could not be modeled on the basis that their toxic action was independent of each other. The application of different models to describe interactions between combinations of metals is discussed. The importance of considering the test species and the exposure period selected for toxicity assessment was highlighted, as was the need to further investigate the toxicity of combinations of pollutants.

Small‐scale Experiments Support Causal Relationships Between Metal Contamination and Macroinvertebrate Community Responses

“…The greater effects in the ZnϩCdϩCu experiment are consistent with results of single-species experiments showing synergistic interactions among metals (Sharma et al 1999, Preston et al 2000, Hansen et al 2002. However, the present study is the first to demonstrate synergistic effects of metals on whole macroinvertebrate communities.…”

Similarity of microbial and meiofaunal community analyses for mapping ecological effects of heavy-metal contamination in soil

“…The measurement of biological properties overcame complications associated with bioavailability, speciation and other interactions of the metals when measuring concentrations by chemical means. The fact that few correlations were observed between the concentrations of individual metals and the individual biological parameters suggests that combinations of metals may affect their overall toxicity in an additive or synergistic manner [18]. However, despite variation between different biological measurements it was apparent that culture‐dependent microbiology was the most discriminatory approach.…”

Construction of a modified mini-Tn5 luxCDABE transposon for the development of bacterial biosensors for ecotoxicity testing

“…The difference in toxicity between dd. H 2 O and groundwater may therefore also have been a consequence of synergistic effects between Cu and other inorganic factors [11]. Chemical analysis would therefore not have equated to ecotoxicity responses.…”