Chemotaxis to aromatic acids by Gram-negative bacteria

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Aromatic compounds are abundant in the biosphere as a major polymeric component of plants (lignin) and as toxic by-products of human industrial activities. Although a reasonable amount is known about how aromatics are degraded by bacteria, not much is known about how bacteria detect the presence of aromatic compounds in the environment. Several genera of motile bacteria, including Pseudomonas, have a strong behavioral attraction to aromatic compounds. This project will study the mechanistic basis for chemotaxis to the aromatic acid, benzoate, by Pseudomonas putida. Our intent is to understand how the receptor that detects these aromatic acids functions and to elucidate the relationship between attractant recognition and biodegradation. Genetic and biochemical experiments are planned to identify the genes necessary for specific behavioral responses to benzoate, and to express and characterize the proteins encoded by these genes. The regulation of the chemotaxis genes and of selected benzoate degradation genes will also be analyzed, with a particular focus on defining DNA sequences and regulatory proteins that are required for gene expression. Since chemotaxis is an important prelude to metabolism, the proposed work could lead to the development of improved strategies for the biodegradation of selected toxic compounds. The receptor protein for benzoate may also have distinctive structural characteristics.