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摘要
Recombinant luminescent Escherichia coli strains could be used to detect the toxicity of pure or mixed contaminants as a light-off sensor. In this work, the lux operon of Photobacterium phosphoreum T3 was identified for the first time. Recombinant luminescent E. coli strains were constructed via expressing the lux operons of P. phosphoreum T3 and Vibrio qinghaiensis Q67 in E. coli MG1655, and the optimal protectant containing 10% (w/v) trehalose and 4% sucrose was used to prepare the freeze-dried recombinant luminescent E. coli cells. Then, these freeze-dried E. coli cells were subjected to acute toxicity detection. The results showed that luminescent E. coli strains displayed sensitive toxic responses to BPA, nFe(2)O(3), Cd, Pb, As, and Hg, for example, the EC50 values of BPA and nFe(2)O(3) to luminescent E. coli strains ranged from 1.54 to 50.19 mg/l and 17.50 to 21.52 mg/l, respectively. Indeed, luminescent E. coli strains exhibited more sensitive responses to Cd, Pb, and Hg than the natural strain Q67. The results suggested that recombinant luminescent E. coli strains could be used for the detection of acute toxicity. Furthermore, the combined toxicities of BPA and nFe(2)O(3), Hg, and Pb were measured, and the joint effects of these mixtures were evaluated with luminescent E. coli. The results indicated that the joint effects of BPA and nFe(2)O(3) suggested to be synergistic or additive to luminescent E. coli, while the joint effects of heavy metals and nFe(2)O(3) exhibited additivities. The cellular endocytosis for Fe2O3 nanoparticles was not observed, which could explain the additive instead of synergistic effects between heavy metals and nFe(2)O(3).
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