title: Hydroxytyrosol from tyrosol using hydroxyphenylacetic acid-induced bacterial cultures and evidence of the role of 4-HPA 3-hydroxylase.
abstract: Hydroxytyrosol (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.
authors.affiliation: Institut de Recherche pour le Développement (IRD), Microbiologie et Biotechnologie des Environnements Extrêmes, UMR_D180, Universités de Provence et de la Méditerranée, 163 avenue de Luminy, case 925, F-13288 Marseille cedex 9, France.
authors.forename: Pierre-Pol
authors.initials: PP
authors.lastname: Liebgott
authors.forename: Agnès
authors.initials: A
authors.lastname: Amouric
authors.forename: Alexia
authors.initials: A
authors.lastname: Comte
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Tholozan
authors.forename: Jean
authors.initials: J
authors.lastname: Lorquin
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D001711:Biotransformation / Q000187:drug effects; D003470:Culture Media / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D020632:Halomonas / Q000201:enzymology; D016982:Micrococcus luteus / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010648:Phenylacetates / Q000378:metabolism*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D012706:Serratia marcescens / Q000201:enzymology; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D003470:Culture Media; D010648:Phenylacetates; D014874:Water Pollutants, Chemical; C005975:3,4-dihydroxyphenylethanol; C011867:4-hydroxyphenylethanol; C008070:4-hydroxyphenylacetic acid; D006899:Mixed Function Oxygenases; C026252:4-hydroxyphenylacetate 3-monooxygenase; D010626:Phenylethyl Alcohol