title: Remediation of waters contaminated with MCPA by the yeasts Lipomyces starkeyi entrapped in a sol-gel zirconia matrix.
abstract: A single-stage sol-gel route was set to entrap yeast cells of Lipomyces starkeyi in a zirconia (ZrO(2)) matrix, and the remediation ability of the resulting catalyst toward a phenoxy acid herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA), was studied. It was found that the experimental procedure allowed a high dispersion of the microorganisms into the zirconia gel matrix; the ZrO(2) matrix exhibited a significant sorption capacity of the herbicide, and the entrapped cells showed a degradative activity toward MCPA. The combination of these effects leads to a nearly total removal efficiency (>97%) of the herbicide at 30 °C within 1 h incubation time from a solution containing a very high concentration of MCPA (200 mg L(-1)). On the basis of the experimental evidence, a removal mechanism was proposed involving in the first step the sorption of the herbicide molecules on the ZrO(2) matrix, followed by the microbial degradation operated by the entrapped yeasts, the metabolic activity of which appear enhanced under the microenvironmental conditions established within the zirconia matrix. Repeated batch tests of sorption/degradation of entrapped Lipomyces showed that the removal efficiency retained almost the same value of 97.3% after 3 batch tests, with only a subsequent slight decrease, probably due to the progressive saturation of the zirconia matrix.
authors.affiliation: Dipartimento di Scienze del Suolo, della Pianta, dell'Ambiente e delle Produzioni Animali, Facoltà di Scienze Biotecnologiche, Università di Napoli Federico II, Via Università 100, 80055 Portici (Napoli), Italy. fsannino@unina.it
authors.forename: Filomena
authors.initials: F
authors.lastname: Sannino
authors.forename: Domenico
authors.initials: D
authors.lastname: Pirozzi
authors.forename: Antonio
authors.initials: A
authors.lastname: Aronne
authors.forename: Esther
authors.initials: E
authors.lastname: Fanelli
authors.forename: Riccardo
authors.initials: R
authors.lastname: Spaccini
authors.forename: Abu
authors.initials: A
authors.lastname: Yousuf
authors.forename: Pasquale
authors.initials: P
authors.lastname: Pernice
mesh_terms: D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000032:analysis / Q000378:metabolism*; D001673:Biodegradation, Environmental; D006540:Herbicides / Q000378:metabolism; D055160:Lipomyces / Q000378:metabolism*; D044367:Phase Transition; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*; D015040:Zirconium / Q000737:chemistry / Q000378:metabolism
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; D015040:Zirconium; D008456:2-Methyl-4-chlorophenoxyacetic Acid; C028541:zirconium oxide