title: Influence of redox mediators and salinity level on the (bio)transformation of Direct Blue 71: kinetics aspects.
abstract: The rate-limiting step of azo dye decolorization was elucidated by exploring the microbial reduction of a model quinone and the chemical decolorization by previously reduced quinone at different salinity conditions (2-8%). Microbial experiments were performed in batch with a marine consortium. The decolorization of Direct Blue 71 (DB71) by the marine consortium at 2% salinity, mediated with anthraquinone-2,6-disulfonate (AQDS), showed the highest rate of decolorization as compared with those obtained with riboflavin, and two samples of humic acids. Moreover, the incubations at different salinity conditions (0-8%) performed with AQDS showed that the highest rate of decolorization of DB71 by the marine consortium occurred at 2% and 4% salinity. In addition, the highest microbial reduction rate of AQDS occurred in incubations at 0%, 2%, and 4% of salinity. The chemical reduction of DB71 by reduced AQDS occurred in two stages and proceeded faster at 4% and 6% salinity. The results indicate that the rate-limiting step during azo decolorization was the microbial reduction of AQDS.
authors: Universidad Autonoma de Nuevo Leon (UANL), Facultad de Ciencias Químicas, Av. Universidad S/N, Cd. Universitaria, San Nicolás de los Garza, 66455, Nuevo León, Mexico. Electronic address: luish.alvarezv@gmail.com.
authors: Luis H
authors: LH
authors: Alvarez
authors: Instituto Tecnológico de Sonora (ITSON), Departamento de Ciencias del Agua y Medio Ambiente, 5 de Febrero 818 sur, 85000, Ciudad Obregón, Mexico.
authors: Edna R
authors: ER
authors: Meza-Escalante
authors: Instituto Tecnológico de Sonora (ITSON), Departamento de Biotecnología y Ciencias Alimentarias, 5 de Febrero 818 sur, 85000, Ciudad Obregón, Mexico.
authors: Pablo
authors: P
authors: Gortáres-Moroyoqui
authors: Instituto Tecnológico de Sonora (ITSON), Departamento de Ciencias del Agua y Medio Ambiente, 5 de Febrero 818 sur, 85000, Ciudad Obregón, Mexico.
authors: Luz
authors: L
authors: Morales
authors: Instituto Tecnológico de Sonora (ITSON), Departamento de Ciencias del Agua y Medio Ambiente, 5 de Febrero 818 sur, 85000, Ciudad Obregón, Mexico.
authors: Krystal
authors: K
authors: Rosas
authors: Universidad Autonoma de Nuevo Leon (UANL), Facultad de Ciencias Químicas, Av. Universidad S/N, Cd. Universitaria, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
authors: Bernardo
authors: B
authors: García-Reyes
authors: Universidad Autonoma de Nuevo Leon (UANL), Facultad de Ciencias Químicas, Av. Universidad S/N, Cd. Universitaria, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
authors: Alicone
authors: A
authors: García-González
mesh_terms: D000880:Anthraquinones / Q000378:metabolism*; D001391:Azo Compounds / Q000378:metabolism*; D004396:Coloring Agents / Q000378:metabolism*; D006812:Humic Substances; D007700:Kinetics; D010084:Oxidation-Reduction; D012256:Riboflavin / Q000378:metabolism; D054712:Salinity; D012623:Seawater / Q000382:microbiology*
chemical_list: D000880:Anthraquinones; D001391:Azo Compounds; D004396:Coloring Agents; D006812:Humic Substances; C408124:anthraquinone-2,6-disulfonate; C408744:Direct Blue 71; D012256:Riboflavin
keywords: Azo dyes; Humic substances; Marine consortium; Redox mediators; Salinity