Chemometric formulation of bacterial consortium-AVS for improved decolorization of resonance-stabilized and heteropolyaromatic dyes Madhava Anil Kumar a , Vaidyanathan Vinoth Kumar b , Manickam Periyaraman Premkumar b , Palanichamy Baskaralingam b , Kadathur Varathachary Thiruvengadaravi b , Anuradha Dhanasekaran c , Subramanian Sivanesan b,⇑ a Department of Chemical Engineering, AC College of Technology, Anna University, Chennai, India b Department of Applied Science and Technology, AC College of Technology, Anna University, Chennai, India c Centre for Biotechnology, AC College of Technology, Anna University, Chennai, India highlights " Bacterial consortium was formulated with three rapid dye decolorizing strains. " The bacterial consortium formulation was done using mixture design matrix under DOE. " Biotransformation of dyes was characterized by UV–vis, HPLC and FT-IR analysis. " Toxicity of dyes and their metabolites were assessed on plant growth parameters. article info Article history: Received 16 May 2012 Received in revised form 24 June 2012 Accepted 26 June 2012 Available online 4 July 2012 Keywords: Pseudomonas desmolyticum Kocuria rosea Micrococcus glutamicus Consortium-AVS Decolorization abstract A bacterial consortium-AVS, consisting of Pseudomonas desmolyticum NCIM 2112, Kocuria rosea MTCC 1532 and Micrococcus glutamicus NCIM 2168 was formulated chemometrically, using the mixture design matrix based on the design of experiments methodology. The formulated consortium-AVS decolorized acid blue 15 and methylene blue with a higher average decolorization rate, which is more rapid than that of the pure cultures. The UV–vis spectrophotometric, Fourier transform infra red spectrophotometric and high performance liquid chromatographic analysis confirm that the decolorization was due to biodegra- dation by oxido-reductive enzymes, produced by the consortium-AVS. The toxicological assessment of plant growth parameters and the chlorophyll pigment concentrations of Phaseolus mungo and Triticum aestivum seedlings revealed the reduced toxic nature of the biodegraded products. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Rapid urbanization, industrialization and technological innova- tions in various disciplines have led to the problem of environmen- tal pollution. The increasing use and release of large amounts of synthetic dyes into the environment causes public concern and legislation problems, and is a serious challenge to environmental scientists (Forgacs et al., 2004). O’Neill et al., 1999 mentioned that annually 16.8% of textile dyes are lost in the effluents. On the basis of the chemical structure of the chromophoric group, dyes are clas- sified as azo, anthraquinone, triphenylmethane, phathalocyanine dyes etc., (Zollinger, 1991). The triphenylmethane (TPM) group of textile dyes has a com- plex aromatic molecular structure, which resists degradation in the environment, resulting in direct and indirect exposure of the human population to high concentration of these dyes. On the ba- sis of their potential for adverse human health effects, the United States Food and Drug Administration listed several TPM dyes as priority chemicals for carcinogenicity testing by the National Tox- icology Program in 1923 (Culp and Beland, 1996). The TPM dyes are more complex, due to the presence of additional phenyl rings in their molecular structure. These resonance-stabilized ring struc- tures impart intense color to fabrics but make the dyes highly re- calcitrant and less susceptible to microbial attack. The heteropolyaromatic thiazine based methylene blue has various harmful effects, and when high concentrations of this dye in the solid form, come into contact with the human eye, have been known to cause corneal and conjunctival injury. Methylene blue 0960-8524/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biortech.2012.06.089 ⇑ Corresponding author. E-mail address: siva@annauniv.edu (S. Sivanesan). Bioresource Technology 123 (2012) 344–351 Contents lists available at SciVerse ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech