title: Steady-state inhibition model for the biodegradation of sulfonated amines in a packed bed reactor.
abstract: Aromatic amines are important industrial products having in their molecular structure one or more aromatic rings. These are used as precursors for the synthesis of dyes, adhesives, pesticides, rubber, fertilizers and surfactants. The aromatic amines are common constituents of industrial effluents, generated mostly by the degradation of azo dyes. Several of them are a threat to human health because they can by toxic, allergenic, mutagenic or carcinogenic. The most common are benzenesulfonic amines, such as 4-ABS (4-aminobenzene sulfonic acid) and naphthalene sulfonic amines, such as 4-ANS (4-amino naphthalene sulfonic acid). Sometimes, the mixtures of toxic compounds are more toxic or inhibitory than the individual compounds, even for microorganisms capable of degrading them. Therefore, the aim of this study was to evaluate the degradation of the mixture 4-ANS plus 4-ABS by a bacterial community immobilized in fragments of volcanic stone, using a packed bed continuous reactor. In this reactor, the amines loading rates were varied from 5.5 up to 69 mg L(-1) h(-1). The removal of the amines was determined by high-performance liquid chromatography and chemical oxygen demand. With this information, we have studied the substrate inhibition of the removal rate of the aromatic amines during the degradation of the mixture of sulfonated aromatic amines by the immobilized microorganisms. Experimental results were fitted to parabolic, hyperbolic and linear inhibition models. The model that best characterizes the inhibition of the specific degradation rate in the biofilm reactor was a parabolic model with values of RXM=58.15±7.95 mg (10(9) cells h)(-1), Ks=0.73±0.31 mg L(-1), Sm=89.14±5.43 mg L(-1) and the exponent m=5. From the microbial community obtained, six cultivable bacterial strains were isolated and identified by sequencing their 16S rDNA genes. The strains belong to the genera Variovorax, Pseudomonas, Bacillus, Arthrobacter, Nocardioides and Microbacterium. This microbial consortium could use the mixture of aromatic amines as sources of carbon, nitrogen, energy and sulfur.
authors.affiliation: Laboratorio de Bioingeniería de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Casco de Santo Tomás, Miguel Hidalgo, 11340 Ciudad de México, Distrito Federal, Mexico. Electronic address: cleotildejr@prodigy.net.mx.
authors.forename: Cleotilde
authors.initials: C
authors.lastname: Juárez-Ramírez
authors.affiliation: Laboratorio de Bioingeniería de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Casco de Santo Tomás, Miguel Hidalgo, 11340 Ciudad de México, Distrito Federal, Mexico. Electronic address: juvenciogm@yahoo.com.
authors.forename: Juvencio
authors.initials: J
authors.lastname: Galíndez-Mayer
authors.affiliation: Laboratorio de Bioingeniería de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Casco de Santo Tomás, Miguel Hidalgo, 11340 Ciudad de México, Distrito Federal, Mexico.
authors.forename: Nora
authors.initials: N
authors.lastname: Ruiz-Ordaz
authors.affiliation: Laboratorio de Bioingeniería de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Casco de Santo Tomás, Miguel Hidalgo, 11340 Ciudad de México, Distrito Federal, Mexico.
authors.forename: Oswaldo
authors.initials: O
authors.lastname: Ramos-Monroy
authors.affiliation: Laboratorio de Bioingeniería de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Casco de Santo Tomás, Miguel Hidalgo, 11340 Ciudad de México, Distrito Federal, Mexico.
authors.forename: Fortunata
authors.initials: F
authors.lastname: Santoyo-Tepole
authors.affiliation: Laboratorio de Biotecnología Ambiental del Centro Nacional de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, Gustavo A. Madero, 07360 Ciudad de México, Distrito Federal, Mexico.
authors.forename: Héctor
authors.initials: H
authors.lastname: Poggi-Varaldo
mesh_terms: D000588:Amines / Q000737:chemistry*; D001173:Arthrobacter / Q000378:metabolism; D001407:Bacillus / Q000378:metabolism; D001673:Biodegradation, Environmental; D018441:Biofilms; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology*; D002851:Chromatography, High Pressure Liquid; D004396:Coloring Agents / Q000737:chemistry; D003470:Culture Media; D004275:DNA, Ribosomal / Q000235:genetics; D007220:Industrial Waste / Q000032:analysis; D009584:Nitrogen / Q000737:chemistry; D009615:Nocardia / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry; D011549:Pseudomonas / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D000588:Amines; D004396:Coloring Agents; D003470:Culture Media; D004275:DNA, Ribosomal; D007220:Industrial Waste; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D009584:Nitrogen; D010100:Oxygen