Benzo[a]pyrene (BaP), a high molecular weight polyaromatic hydrocarbon (HMW PAH) is commonly found in contaminated soils and considered as a potent carcinogen. Microbial degradation offers an effective approach to remove toxic pollutants. In this study, four types of yeast strains viz. Rhodotorula sp. NS01, Hanseniaspora opuntiae NS02, Debaryomyces hansenii NS03 and Hanseniaspora valbyensis NS04 isolated from BaP contaminated soil were used for the degradation of BaP. Identification of yeast isolates was done using 18S rRNA sequences. Out of four consortia studied, YC01, consisting of Rhodotorula sp. NS01, Hanseniaspora opuntiae NS02 and Debaryomyces hansenii NS03, was found to show a maximum BaP degradation of 76% within 6 days in aqueous medium under optimized conditions viz. pH 7.0, temperature 30 ºC, shaking speed of 130 rpm, an inoculum dosage 3% (w/v) and an initial BaP concentration of 50 mg/L. Degradation of benzo[a]pyrene by the consortium YC01 exhibited first order kinetics with half-life period of 3.03 days. The degradation products were monitored by Fourier transform infrared spectroscopy (FTIR), Gas Chromatography Mass Spectrometry (GC-MS) analysis. A possible pathway of BaP degradation by yeast consortium, YC01 was proposed. Significant role of enzymes like laccase, 1,2- dioxygenase, 2,3-dioxygenase, lignin peroxidase, manganese peroxidase and catalase were noted during the process of BaP degradation. To the best of our knowledge, this is the first report on the use of yeast consortium towards BaP degradation.
