Abstract
Chemotaxis is the movement organisms toward chemical attractants and away from chemical repellents. Pseudomonas aeruginosa has chemotactic responses to a wide range of chemical stimuli. In this study, chemotaxis to environmental pollutants and their derivatives such as aromatic and volatile chlorinated aliphatic compounds were investigated in P. aeruginosa using the computer-assisted capillary method. P. aeruginosa was found to be attracted by p-toluate, m-aminobenzoate, dinitrosalicylate, o-chlorobenzoate, catechol, 2,4-dichlorophenoxyacetate (2,4-D) and 2,4,5-trichlorophenoxyacetate (2,4,5-T). Volatile chlorinated aliphatic compounds including trichloroethylene, trichloroethane, tetrachloroethylene, and chloroform elicited negative chemotactic responses of P. aeruginosa. Chemotaxis assays of the P. aeruginosa cheR mutant revealed that cheR encoding a methyl-accepting chemotaxis protein (MCP) methyltransferase, suggesting that chemotaxis toward these compounds are dependent on MCPs. P. aeruginosa possesses 26 putative MCP genes on its genome. A series of mutants that have deletion-insertion mutations in individual mcp genes and examined for chemotactic responses to these attractants and repellents. All the mutants showed normal responses to theses compounds. This result suggests that multiple MCPs are involved in detection of each of these attractants and repellents like detection of inorganic phosphate, amino acids, and oxygen.
