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The isolation of a Pseudomonas putida DTB bacterium capable of utilizing N,N-diethyl-m-toluamide (DEET) as sole carbon and energy source and hydrolyzing DEET into 3-methylbenzoate and diethylamine is reported.

Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a b-barrel with a hydrophobic inner chamber. A co-crystal structure of VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment. [ABSTRACT FROM AUTHOR]

The initial step in the biodegradation pathway of N, N-diethyl- m-toluamide (DEET) in Pseudomonas putida strain DTB is catalyzed by DEET hydrolase (DthA), which hydrolyzes the amide bond to yield 3-methylbenzoic acid and diethylamine. In order to extend our understanding of DthA, the enzyme was purified and characterized. The enzyme is most active at pH 7.9, and is probably a tetramer in its native state. The kinetic parameters of the wild-type enzyme are Km = 10.2 ± 0.8 μ m, kcat = 5.53 ± 0.09 s−1, and kcat/ Km = (5.4 ± 0.4) × 105 m−1·s−1. Mild substrate inhibition was observed with DEET concentrations over 500 μ m. A homology model of DthA was used to guide mutational analysis of the active site, confirming that the catalytic triad is formed by Ser166, Ap292, and His320. The oxyanion hole is formed by the side chain OH of Tyr84 and the backbone amide of Trp167, with the Tyr84 OH being essential for enzyme activity. The DthA model also revealed a hydrophobic substrate-binding pocket comprosed of Trp167, Met170, and Trp214. W167A and M170A mutations decreased enzymatic activity and exacerbated substrate inhibition, whereas Trp214, which probably plays a role in substrate recognition, was essential for enzymatic activity. The pH rate profile of DthA was fitted to two ionizable groups (p Ka1 = 6.1 and p Ka2 = 9.9) that probably correspond to Nε of His320 and the OH of Tyr84, respectively. In addition to catalyzing the hydrolysis of DEET, DthA hydrolyzed a variety of esters and amides. Database Model data are available in the PMDB database under the accession number . Structured digital abstract [ABSTRACT FROM AUTHOR]

This article attempts to summarize what is known in general concerning the role of biological degradation of pharmaceutical and personal care products (PPCPs) in wastewater as well as in natural environments. It describes several instances in which the use of PPCPs as bacterial growth substrates has been demonstrated. It also provides several examples detailing what is known about the metabolism of alkylphenol, DEET and ibuprofen.