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Bacterial Chemotaxis to Naphthalene and Nitroarene Compounds

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Final rept. 1 Jul 2004-30 Jun 2008

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Bacteria that can both degrade and sense pollutants using chemotaxis may be more efficient in biodegradation. Ralstonia sp. U2 mineralizes naphthalene, and Acidovorax sp. JS42 utilizes the man-made compound 2-nitrotoluene 2NT. Capillary assays were performed with wild-type and catabolic and regulatory mutants of these strains. The results showed that wild-type Ralstonia sp. U2 is chemotactic to naphthalene, the chemotactic response is induced when cells are grown with naphthalene, and insertional inactivation of nagR, which encodes the transcriptional activator of the naphthalene catabolic genes, had no affect on chemotaxis to naphthalene. The results indicate that NagR is not required for naphthalene chemotaxis, and naphthalene is detected directly. 2NT-induced wild-type JS42 showed a stronger response to 2NT than uninduced cells. Mutant strains unable to degrade 2NT did not show an inducible response to 2NT, but did respond like uninduced wild type. The inducible response was lost when JS42 was exposed to a competing energy source. Thus, JS42 uses two types of 2NT taxis 2NT-specific chemotaxis and metabolism-dependent energy taxis, in which the energy generated from 2NT metabolism is detected. The chemotactic response is constitutive, while energy taxis is induced during exposure to 2NT and other inducers of the 2NT degradation genes.

Subject Categories:

  • Biochemistry
  • Anatomy and Physiology
  • Organic Chemistry

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