Bacterial chemotaxis to environmental pollutants and it''s significance in bioremediation
细菌对环境污染物的趋化性及其在生物修复中的作用

Release of pollutants has resulted in environmental contamination. Many methods have been applied to remove xenobiotic compounds, and bioremediation was considered as a safer, more efficient and less expensive alternative to treat these pollutants. Although many environmental pollutants are found to be degraded by microorganisms, in some cases, the catabolic potential alone was inadequate, combining with other properties such as chemotaxis to enhance bioremediation has been considered. Bacterial chemotaxis, movement of bacteria under the influence of a chemical gradient helped bacteria to navigate to the most favorable niches for growth and survival, and it might have evolved as a selective advantage to bacteria for searching the chemicals that could act as a source of carbon and energy to the cells. Chemotaxis could play an important role in the biodegradation process. The relationships between chemotaxis and degradation have been studied with increasing efforts. In this review, the basic concept and assay methods of bacterial chemotaxis and it's signal transduction mechanism are introduced. Bacterial chemotaxis to environmental pollutants is discussed in detail, and evidences that motile bacteria are chemotactically attracted to environmental pollutants, which they could degrade, are listed. The relationships between chemotaxis and degradation characteristics are discussed on genetic levels, and the evidences demonstrating that chemotaxis and biodegradation genes of 4-hydroxybenzoate, toluene, naphthalene and 2,4-D were coordinately regulated suggesting that these processes are intimately linked in nature. Chemotaxis could enhance degrading ability in bioremediation, and knowledge of bacterial chemotaxis toward xenobiotics could be applied in designing efficient systems for bioremediation of contaminated sites.