Study On Toxicity Assessment Of Pollutants Using CellSense Biosensor

Biosensor is an analytical device that combines a biological sensing element (such as enzyme, microorganisms, DNA etc) with a transducer to produce a biological signal that could be converted into a measurable response for later analysis. The main advantages offered by biosensors over conventional analytical techniques are the possibility of miniaturization, rapid detection, and working on-site etc. Biosensors can be used as environmental quality monitoring tools.On the base of optimization of the analytical parameters and microorganism immobilization methods by using commercial CellSense biosensors with E.coli, CellSense biosensor with different microorganisms such as E.coli Top 10, Bacillus subtilis and Proteus mirabilis are constructed and optimized in this dissertation. Their performances for toxicity tests of heavy metals, organic matters and leachates from different treatment units are also investigated.The results showed that p-benzoquinone can be used as an excellent mediator for CellSense biosensor, and the suitable toxicity inhibition time is about 30min. Iinhibitory effects of four heavy metals to commercial E.coli can be ranked in a decreasing order of Hg²⁺>Cu²⁺>Zn²⁺>Ni²⁺, which accords to the results of conventional bacterial counting method. The CellSense biosensor with E.coli also shows a good, reproducible behavior when testing toxicity of heavy metals, the RSD is less than 5%. The toxicity tests of organic compounds within certain concentration ranges using CellSense biosensor also gain satisfying results.Research on microorganism immobilization methods showed that polycarbonate membrane immobilization method exhibited the best toxicity test performance. Those biosensors keep very stable within two month in 4℃refrigerator, and no distinct difference is showed in toxicity test results. CellSense biosensors made by using GA-BSA immobilization method, PVA—H₃BO₃ and sodium alginate entrapment method do not suit for the toxicity analysis.Differences exist among Cellsense biosensors with the same microorganism at different cultivation periods. It was observed that CellSense biosensors with E.coli TOP 10,Bacillus subtilis and Proteus mirabilis at late-log phase show better response performances.The leachate toxicity test results also showed that lab-made E.coli biosensor can reflect toxicity change of leachate samples from different treatment units.CellSense biosensor is a useful and promising device for toxicity test and assessment of different pollutants, which possesses the merits of convenience, sensitive and fast detection, and on-line analysis.