An integrated mini biosensor system for continuous water toxicity monitoring

An integrated water toxicity monitoring system that uses recombinant bioluminescent bacteria was successfully developed for the continuous monitoring and classification of toxicities present in water. This system consists of four channels arranged horizontally inside of a cylinder, with each channel having two small bioreactors that are vertically connected to each other to maintain a separation of the culture reactor from test reactor. This system is easily handled and installed, making its application in the field a potential reality. As well, it performed stably and continuously due to the vertical separation of the culture reactor from the test reactor and a long term operation was also performed because of its small working volume, i.e., only 1 ml for the 1st bioreactor and 2 ml for the 2nd. During an operation with four strains, i.e., EBHJ2, DP1, DK1 and DPD2794, which are responsive to superoxide damage (EBHJ2 and DP1), hydrogen peroxide (DK1), and DNA damage (DPD2794), the O.D. and bioluminescence of the bacterial cultures inside the system were constant when no chemical was injected. However, with the addition of paraquat, hydrogen peroxide or mitomycin C, the bioluminescent responses of the strains were found to be dose-dependent to different concentrations of these chemicals.