n this study, we used optimized luminescent bacteria (vibrio harveyi A92M8) as a potential microbial biosensor for toxicity assessment of pesticides, herbicides and poisonous synthetic materials in environment. Immobilization of natural luminescent bacteria on silica gel 57.3% Si(OSi)4, glass beads, calcium alginate 2wt% and chitosan 0.10 to 25.0×10−2 mol/dm3 was examined. Methods for immobilization were encapsulation in gel polymers, entrapment, and absorption on the surface. Bacterial cells were encapsulated in calcium alginate and agar 3%, entrapped in silica gel and absorbed in chitosan. Luminescence output of immobilized bacteria decreased for silica gel 50%, glass beads 10%, calcium alginate5% and chitosan 10%. However, immobilized cells were more viable and produced light for a longer period compared to free cells. Also response reaction rate of immobilized luminescent cell to tested toxicants was higher than free cells as sensitivity increased for silica gel, glass beads, calcium alginate and chitosan up to 20%, 32%, 30%, and 25% respectively. In conclusion for the first time we could successfully immobilize natural luminescent bacteria in different matrices. Also cells were alive and active in producing light when immobilized on surface of chitosan which might be an appropriate tool for biologically sensing of environmental pollutants.

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