Effects of Binary Mixtures of Inducers (Toluene Analogs) and of Metals on Bioluminescence Induction of a Recombinant Bioreporter Strain

Abstract

This paper investigated the effects of binary mixtures of bioluminescence inducers (toluene, xylene isomers, m-toluate) and of metals (Cu, Cd, As(III), As(V), and Cr) on bioluminescence activity of recombinant (Pm-lux) strain KG1206. Different responses and sensitivities were observed depending on the types and concentrations of mixtures of inducers or metals. In the case of inducer mixtures, antagonistic and synergistic modes of action were observed, whereas metal mixtures showed all three modes of action. Antagonistic mode of action was most common for mixtures of indirect inducers, which showed bioluminescence ranging from 29% to 62% of theoretically expected effects (P(E)). On the other hand, synergistic mode of action was observed for mixtures of direct and indirect inducers, which showed bioluminescence between 141% and 243% of P(E).In the case of binary metal mixtures, bioluminescence activities were ranged from 62% to 75% and 113% to 164% of P(E) for antagonistic and synergistic modes of action, respectively (p-values 0.0001–0.038). Therefore, mixture effects could not be generalized since they were dependent on both the types and concentrations of chemicals, suggesting that biomonitoring may constitute a better strategy by investigating types and concentrations of mixture pollutants at contaminated sites.

Analysis of Bioavailable Toluene by Using Recombinant Luminescent Bacterial Biosensors with Different Promoters

“…coli is suitable for application in various water environments (groundwater, river water, and seawater), whereas T7-lux-E. coli is suitable for use in relatively low ionic strength environments, except seawater. [12,31,32]. The current results demonstrated that the coexistence of sodium lactate or glycerin with toluene induced higher luminescence activity than did toluene alone.…”

“…Taken together, these results illustrate that our recombinant luminescent biosensor possesses high selectivity and specificity when detecting a group of analytes with similar chemical structures. Because the included chemicals mainly affect the regulatory genes xylS or xylR, but not the T3, SP6, or T7 promoter, their effects on the magnitude of luminescence activity among all three recombinant E. coli biosensors were similar [12]. Figure exemplifies the case of T7-lux-E. coli.…”

“…Over the last 20 years, biosensors have been developed and are widely used as simple and practical approaches for the sensitive and specific detection of various compounds, including organic compounds (pesticides and chlorophenol), heavy metals (mercury, zinc, and cadmium), and some inorganic compounds [9][10][11]. Whole-cell biosensors rely on gene expression analysis: transcriptional fusions between a promoter and a reporter gene are created, and the extent of reporter gene expression is used to indicate the pollutant concentration [12]. Several engineered biosensors have specifically discriminated between alkyl-substituted benzene derivatives in water samples [13].…”

“…A biosensor of this type can be genetically engineered by placing a reporter gene, such as lacZ, gfp, luc, or lux, under the control of a transcriptional activator [11,14]. Under appropriate conditions (e.g., in the presence of specific pollutant), the biosensor can produce a detectable signal (color or luminescence) that is directly correlated to the pollutant concentration [12,15]. This can aid in directly correlating the toluene concentration with the reporter enzyme activity.…”

Analysis of Bioavailable Toluene by Using Recombinant Luminescent Bacterial Biosensors with Different Promoters

“…Effects of coexisting carbon sources, intermediates, and toluene analogs on luminescence activity Figure 4A illustrates the effects of coexisting carbon sources at 100 μM on the luminescence activity of T7-lux-E. coli and SP6-lux-E. coli. The tested chemicals are considered potential inhibitors or activators (indirect or direct inducers) of xylS and xylR and may deviate signi cantly or be additive effect in relation to theoretically expected effects, calculated on the basis of individual chemicals [12,31,32]. The current results demonstrated that the coexistence of sodium lactate or glycerin with toluene induced higher luminescence activity than did toluene alone.…”