Enhanced biodegradation of 4-chlorophenol by Candida tropicalis PHB5 via optimization of physicochemical parameters using Taguchi orthogonal array approach

Candida tropicalis PHB5 was able to grow on 4-chlorophenol and to metabolize this substrate. 4-Chlorophenol degradation proceeds through a pathway involving transient production of three key metabolites 4-chlorocatechol, 4-chloropyrogallol and 4-carboxymethelenebut-2-en-4-olide which were identified by HPLC analysis. The Taguchi orthogonal array design methodology was used to improve the 4-chlorophenol biodegradation ability of strain PHB5. At 3 levels, an orthogonal array was selected to analyze the effects of the different physicochemical process factors. Experiments were undertaken to study the effects of eleven factors affecting the growth of C tropicalis on 4-chlorophenol and its degradation. Taguchi methodology predicted that biomass yield on 4-chlorophenol could be increased from 409.7 mg l(-1) to 1046.9 mg l(-1) and the amount of 4-chlorophenol degraded could be increased from 314.5 mg l(-1) to 949.7 mg l(-1). Based on Taguchi methodology, an overall enhancement of growth by 155.5% and of 4-chlorophenol degradation by 201.9% were predicted. The predicted values were validated by experimental data which showed than under optimal cultural conditions, the biomass yield was increased by 141.62% and 4-CP degradation by 183%. (c) 2012 Elsevier Ltd. All rights reserved.