An oxidative stress-specific bacterial cell array chip for toxicity analysis

An oxidative stress-specific bacterial cell array chip was fabricated and implemented in the analysis of various different chemicals. The chip consisted of twelve toxicity responsive strains that respond specifically to different oxidative toxicities such as the generation of the superoxide radical, except for strain EBMalK, which was included as a negative control. Each bioluminescent strain carried a fusion of a stress gene promoter (sodA, pqi-5, soxR, fumC, soxS, inaA, hmp, malK, katG, zwf, fpr or pgi) to the bacterial lux reporter genes. A total of nine chemicals were selected to exhibit the capabilities of this array when analyzing different oxidative toxicities. Each of the chemicals were categorized according to their structure and their ability to form radicals in vivo: (I) paraquat, an active radical producer, (II) structural analogs of paraquat that produce radicals, (III) chemicals that are distinct from paraquat but still produce radicals and (IV) chemicals having similar structures as paraquat but do not produce radicals. The results found that each strain was responsive to one or more of the compounds tested but, as a definitive factor, the responses from the chip were dependent upon the production of radicals, i.e., the strains were unresponsive to compounds that were similar in structure to paraquat but lacked the ability to generate radicals. The specificity of the strains used in the chip was also demonstrated by their ability to discriminate between the superoxide radical and hydrogen peroxide. Therefore, this cell array chip could be implemented in characterizing and understanding the toxic impacts of newly synthesized chemicals and drugs in terms of toxicity classification and the nature of oxidative damage experienced by cells.