earticle

영어

Trichloroethylene (TCE) is the most frequently detected groundwater contaminants. Recent researches have demonstrated that TCE elicits positive chemotaxis (attractive response) in certain bacterial strains, most of which are capable of degrading TCE in the presence of toluene. Chemotatic responses to TCE by these TCE-degrading bacteria are expected to overcome mass-transfer limitation that impedes bioremediation processes and increase speed of biodegradation processes. However, little is known about the mechanisms at the molecular level. Psedomonas aeruginosa PAO1 is strongly repelled by TCE. Genetic analysis of negative chemotaxis (repelled response) to TCE by P. aeruginosa PAO1 revealed that the methyl-accepting chemotaxis proteins (MCPs) PctA, PctB and PctC which were identified as MCPs for amino acid, serve as the major chemoreceptors for the negative chemotaxis to TCE. Furthermore, we found that the pctABC triple mutant of P. aeruginosa PAO1 was attracted by TCE. P. aeruginosa PAO1 possesses 26 potential mcp genes in its genome. Chemotaxis assays of a set of mutants containing deletions in 26 potential mcp genes revealed that mcpA (PA0180) is the chemorecepter for positive chemotaxis to TCE. McpA also detects tetrachloroethylene and dichloroethylene isomers as attractants. Moreover, Pseudomonas putida F1, which is capable of degrading TCE, grown in the absence of toluene fail to respond to TCE. We introduced mcpA into P. putida F1 and the strain was attracted by TCE even when grown in the absence of toluene. We also found the chemoreceptor for positive chemotaxis to TCE in P. putida F1.