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Applied and Environmental Microbiology, June 2001, p. 2404-2409, Vol. 67, No. 6
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.6.2404-2409.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

Hydrolysis of 4-Hydroxybenzoic Acid Esters (Parabens) and Their Aerobic Transformation into Phenol by the Resistant Enterobacter cloacae Strain EM

Nelly Valkova, François Lépine,* Loredana Valeanu, Maryse Dupont, Louisette Labrie, Jean-Guy Bisaillon, Réjean Beaudet, François Shareck, and Richard Villemur

INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada H7V 1B7

Received 29 November 2000/Accepted 16 March 2001

Enterobacter cloacae strain EM was isolated from a commercial dietary mineral supplement stabilized by a mixture of methylparaben and propylparaben. It harbored a high-molecular-weight plasmid and was resistant to high concentrations of parabens. Strain EM was able to grow in liquid media containing similar amounts of parabens as found in the mineral supplement (1,700 and 180 mg of methyl and propylparaben, respectively, per liter or 11.2 and 1.0 mM) and in very high concentrations of methylparaben (3,000 mg liter-1, or 19.7 mM). This strain was able to hydrolyze approximately 500 mg of methyl-, ethyl-, or propylparaben liter-1 (3 mM) in less than 2 h in liquid culture, and the supernatant of a sonicated culture, after a 30-fold dilution, was able to hydrolyze 1,000 mg of methylparaben liter-1 (6.6 mM) in 15 min. The first step of paraben degradation was the hydrolysis of the ester bond to produce 4-hydroxybenzoic acid, followed by a decarboxylation step to produce phenol under aerobic conditions. The transformation of 4-hydroxybenzoic acid into phenol was stoichiometric. The conversion of approximately 500 mg of parabens liter-1 (3 mM) to phenol in liquid culture was completed within 5 h without significant hindrance to the growth of strain EM, while higher concentrations of parabens partially inhibited its growth.


* Corresponding author. Mailing address: INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, Québec, Canada, H7V 1B7. Phone: (514) 687-5010. Fax: (514) 686-5501. E-mail: francois_lepine{at}inrs-iaf.uquebec.ca.


Applied and Environmental Microbiology, June 2001, p. 2404-2409, Vol. 67, No. 6
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.6.2404-2409.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.



This article has been cited by other articles:

  • Valkova, N., Lepine, F., Labrie, L., Dupont, M., Beaudet, R. (2003). Purification and Characterization of PrbA, a New Esterase from Enterobacter cloacae Hydrolyzing the Esters of 4-Hydroxybenzoic Acid (Parabens). J. Biol. Chem. 278: 12779-12785 [Abstract] [Full Text]  
  • Valkova, N., Lepine, F., Bollet, C., Dupont, M., Villemur, R. (2002). prbA, a Gene Coding for an Esterase Hydrolyzing Parabens in Enterobacter cloacae and Enterobacter gergoviae Strains. J. Bacteriol. 184: 5011-5017 [Abstract] [Full Text]