title: Use of RSM modeling for optimizing decolorization of simulated textile wastewater by Pseudomonas aeruginosa strain ZM130 capable of simultaneous removal of reactive dyes and hexavalent chromium.
abstract: Remediation of colored wastewater loaded with dyes and metal ions is a matter of interest nowadays. In this study, 220 bacteria isolated from textile wastewater were tested for their potential to decolorize each of the four reactive dyes (reactive red-120, reactive black-5, reactive yellow-2, and reactive orange-16) in the presence of a mixture of four different heavy metals (Cr, Zn, Pb, Cd) commonly found in textile effluents. Among the tested bacteria, the isolate ZM130 was found to be the most efficient in decolorizing reactive dyes in the presence of the mixture of heavy metals and was identified as Pseudomonas aeruginosa strain ZM130 by 16S rRNA gene analysis. The strain ZM130 was highly effective in simultaneously removing hexavalent chromium (25 mg L(-1)) and the azo dyes (100 mg L(-1)) from the simulated wastewater even in the presence of other three heavy metals (Zn, Pb, Cd). Simultaneous removal of chromium and azo dyes ranged as 76.6-98.7 % and 51.9-91.1 %, respectively, after 180 h incubation. On the basis of quadratic polynomial equation and response surfaces given by the response surface methodology (RSM), optimal salt content, pH, carbon co-substrate content, and level of multi-metal mixtures for decolorization of reactive red-120 in a simulated textile wastewater by the strain ZM130 were predicted to be 19.8, 7.8, and 6.33 g L(-1) and a multi-metal mixture (Cr 13.10 mg L(-1), Pb 26.21 mg L(-1), Cd 13.10 mg L(-1), Zn 26.21 mg L(-1)), respectively. Moreover, the strain ZM130 also exhibited laccase and nicotinamide adenine dinucleotide (reduced)-dichlorophenolindophenol reductase (NADH-DCIP reductase) activity during the decolorization of reactive red-120. However, the laccase activity was found to be maximum in the presence of 300 mg L(-1) of the dye as compared to other concentrations. Hence, the isolation of this strain might serve as a potential bio-resource required for developing the strategies aiming at bioremediation of the wastewater contaminated with dyes and heavy metals.
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000, Faisalabad, Pakistan.
authors.forename: Zahid
authors.initials: Z
authors.lastname: Maqbool
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000, Faisalabad, Pakistan. sabirghani@gmail.com.|UCD School of Biomolecular and Biomedical Sciences, University College Dublin, Belfield, Dublin 4, Ireland. sabirghani@gmail.com.
authors.forename: Sabir
authors.initials: S
authors.lastname: Hussain
authors.affiliation: Department of Statistics, Government College University, Faisalabad, Pakistan.
authors.forename: Tanvir
authors.initials: T
authors.lastname: Ahmad
authors.affiliation: Department of Bioinformatics and Biotechnology, Government College University, Faisalabad, Pakistan.
authors.forename: Habibullah
authors.initials: H
authors.lastname: Nadeem
authors.affiliation: Department of Soil Science, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan.|Soil Science Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, 38000, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Imran
authors.affiliation: Department of Environmental Sciences, PMAS Arid Agriculture University, Rawalpindi, Pakistan.
authors.forename: Azeem
authors.initials: A
authors.lastname: Khalid
authors.affiliation: Department of Plant Pathology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakaria University, Multan, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Abid
authors.affiliation: INRA, UMR 1347 Agroécologie, 17 Rue Sully, BP 86 510, 21065, Dijon, Cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Martin-Laurent
mesh_terms: D001391:Azo Compounds / Q000032:analysis; D001673:Biodegradation, Environmental; D002857:Chromium / Q000032:analysis*; D004396:Coloring Agents / Q000032:analysis*; D042845:Laccase / Q000378:metabolism; D019216:Metals, Heavy / Q000032:analysis*; D008962:Models, Theoretical; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000254:growth & development* / Q000302:isolation & purification; D011808:Quinone Reductases / Q000378:metabolism; D012336:RNA, Ribosomal, 16S; D013783:Textile Industry; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D001391:Azo Compounds; D002857:Chromium; D004396:Coloring Agents; D042845:Laccase; D019216:Metals, Heavy; D011808:Quinone Reductases; D012336:RNA, Ribosomal, 16S; D062065:Wastewater; D014874:Water Pollutants, Chemical; C074702:chromium hexavalent ion; C033633:dichlorophenolindophenol reductase
keywords: Biodecolorization; Cr(VI) reduction; Laccase and NADH-DCIP reductase; Multi-metal mixture stress; Pseudomonas; Response surface methodology (RSM)