title: 4-Chlorophenol degradation by a bacterial consortium: development of a granular activated carbon biofilm reactor.
abstract: A bacterial consortium that can degrade chloro- and nitrophenols has been isolated from the rhizosphere of Phragmitis communis. Degradation of 4-chlorophenol (4-CP) by a consortium attached to granular activated carbon (GAC) in a biofilm reactor was evaluated during both open and closed modes of operation. During the operation of the biofilm reactor, 4-CP was not detected in the column effluent, being either adsorbed to the GAC or biodegraded by the consortium. When 4-CP at 100 mg l-1 was fed to the column in open mode operation (20 mg g-1 GAC total supply), up to 27% was immediately available for biodegradation, the rest being adsorbed to the GAC. Biodegradation continued after the system was returned to closed mode operation, indicating that GAC bound 4-CP became available to the consortium. Biofilm batch cultures supplied with 10-216 mg 4-CP g-1 GAC suggested that a residual fraction of GAC-bound 4-CP was biologically unavailable. The consortium was able to metabolise 4-CP after perturbations by the addition of chromium (Cr VI) at 1-5 mg l-1 and nitrate at concentrations up to 400 mg l-1. The development of the biofilm structure was analysed by scanning electron microscopy and confocal laser scanning microscopy (CLSM) techniques. CLSM revealed a heterogeneous structure with a network of channels throughout the biofilm, partially occupied by microbial exopolymer structures.
authors.affiliation: Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Porto, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Caldeira
authors.forename: S C
authors.initials: SC
authors.lastname: Heald
authors.forename: M F
authors.initials: MF
authors.lastname: Carvalho
authors.forename: I
authors.initials: I
authors.lastname: Vasconcelos
authors.forename: A T
authors.initials: AT
authors.lastname: Bull
authors.forename: P M
authors.initials: PM
authors.lastname: Castro
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development; D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D002733:Chlorophenols / Q000378:metabolism*; D002857:Chromium / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000502:physiology*; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000502:physiology*; D009566:Nitrates / Q000494:pharmacology; D006109:Poaceae; D012988:Soil Microbiology
chemical_list: D002733:Chlorophenols; D009566:Nitrates; D002857:Chromium; C074702:chromium hexavalent ion; C029107:4-chlorophenol; D002244:Carbon