LiebgottP-P.auteurautAmouricA.auteurautComteA.auteurautTholozanJean-LucauteurautLorquinJeanauteurautIRDtextjournalArticletext/pdfborn digitalaccessHydroxytyrosol (HTyr) is a potent natural antioxidant found in olive mill wastewaters. Bacterial conversion of 4-tyrosol (2-(4-hydroxyphenyl)-ethanol) to HTyr was reported in a limited number of bacterial species including Pseudomonas aeruginosa. In this work, we studied this conversion, taking as a model the newly isolated Halomonas sp. strain HTB24. It was first hypothesized that the enzyme responsible for 4-tyrosol hydroxylation in HTyr was a 4-hydroxyphenylacetic acid 3-hydroxylase (HPAH, EC 1.14.13.3), previously known to convert 4-hydroxyphenylacetic acid (4-HPA) into 3,4-dihydroxyphenylacetic acid (3,4-DHPA) in P. aeruginosa. Cloning and expression of hpaB (oxygenase component) and hpaC (reductase component) genes from P. aeruginosa confirmed this hypothesis. Furthermore, using cultures of HTB24 containing 4-tyrosol, it was shown that 4-HPA accumulation preceded 4-tyrosol hydroxylation. We further demonstrated that the synthesis of HPAH activity was induced by 4-HPA, with the latter compound being formed from 4-tyrosol oxidation by aryl-dehydrogenases. Interestingly, similar results were obtained with other 4-HPA-induced bacteria, including P. aeruginosa, Serratia marcescens, Escherichia coli, Micrococcus luteus and other Halomonas, thus demonstrating general hydroxylating activity of 4-tyrosol by the HPAH enzyme. E. coli W did not have aryl-dehydrogenase activity and hence were unable to oxidize 4-tyrosol to 4-HPA and HTyr to 3,4-DHPA, making this bacterium a good candidate for achieving better HTyr production.specializedHydroxytyrosolTyrosolInduction4-hydroxyphenylacetic acid4-HPA3-hydroxylase084 1601075776620090923-2508http://www.documentation.ird.fr/hor/fdi:01004909910.1016/j.resmic.2009.09.015IRD BondyF B010049099http://www.documentation.ird.fr/hor/fdi:010049099http://www.documentation.ird.fr/intranet/publi/2010/01/010049099.pdfAccès réservé (Intranet de l'IRD)IRD - Base Horizon / Pleins textes2010-02-082010-02-08fdi:010049099fre