Toxicity biomonitoring of degradation byproducts using freeze-dried recombinant bioluminescent bacteria

A toxicity biomonitoring system using freeze-dried recombinant bioluminescent bacteria was implemented to diagnose the biotreatment of 2,4,5-trichlorophenol and its degradation byproducts of using a cell-free culture broth of Phanerochaete chrysosporium. The cellular toxicity was measured by the bioluminescence of constitutive bioluminescent bacteria, such as Photobacterium phosphoreum and GC2, while information on the toxicity caused by unknown byproducts was obtained using the specific bioluminescent responses of stress-inducible bioluminescent bacteria, which included DPD2540 (membrane-damage sensitive), TV1061 (protein-damage sensitive), DPD2794 (DNA-damage sensitive), and DPD2511 (oxidative-damage sensitive) strains. An overall decrease in the cellular toxicity was observed as the treatment progressed, i.e. as 2,4,5-trichlorophenol disappeared. On the other hand, bioluminescent responses from DPD2511, DPD2540, and TV1061 increased as degradation progressed, most probably due to the formation of byproducts causing oxidative-, membrane-, and protein-damage. In conclusion, this toxicity biomonitoring method may be applied to evaluate the toxicities of degradation byproducts of the other environmental processes to provide more information about the mode of the byproducts' toxicity.