| Microorganism chemotaxis, movement under the influence of a pollutant chemical gradient, either toward or away from the gradient helps microorganism to find optimum conditions for their growth and survival. Chemotaxis may be the prelude of degradation and enhances the biodegradation. It is the advantage of natural selection when microorganism is insufficient in nutrition or face the pollutant. The study the mechanism of chemotaxis can make us know microorganism carries on one's own transformation and adapts to the process to the abominable environment even more. This main content of this thesis is divided into three chapters altogether: Chapter one summarizes the current situation of the environmental pollution, concentrate on danger of the aromatic hydrocarbon mainly, discuss the advantage of the biological method among several kinds of methods. And summarize the current situation and research developing of bacterial chemotaxis, and illustrate the mechanism of bacterial chemotaxis.Chapter two we having proved Ralstonia sp. strain U2 were chemotatic to its substrate compound naphthalene and other chemical compounds for example salicylate, succinate, gentisate in terms of experiment, we also clone the one of chemotaxis gene:methyl-accepting chemotaxis gene(MCP gene) and express the protein in E.coli Rosetta. SDS-PAGE showed the protein is about 52.9kD in line with the academic value. We also analyze the function of the MCP gene in drop assay. Chapter three we verified the chemotactic character of Pseudomonas sp.WBC-3, plasmid-transfer strain WXP-6 and plasmid-remove strain WBC-C to Parathion-Methyl. The metabolize plasmid of strain WBC-3 play a certain role in chemotaxis. We also proved the chemotaxis has no affirm correlation with the metabolism.
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