Optimization of process parameters for the yeast mediated degradation of benzo[a]pyrene in presence of ZnO nanoparticles and produced biosurfactant using 3-level Box-Behnken design

In the present study, response surface methodology (RSM) employing 3-level Box-Behnken design was used to optimize the parameters for benzo[a]pyrene (BaP) degradation using yeast consortium YC01 in presence of zinc oxide nanoparticles and produced biosurfactant in the growth medium. The biosurfactant producing ability of YC01 was investigated by drop collapsing test, methylene blue agar plate method and emulsification index (E24). Various process parameters viz. pH (A: 5.0-9.0), temperature (B: 10-50° C), shaking sped (C: 110-150 rpm), inoculum dosage (D: 1-5%) and ZnO nanoparticle concentration (E: 1-3 g/L) were chosen for optimization. Maximum BaP degradation was found to be 82.67 ± 0.01 (%) at central values of all the factors viz., pH 7.0, temperature 30 °C and shaking speed 130 rpm in the presence of 2 g/L of ZnO nanoparticle using 3% inoculum dosage of yeast consortium YC01 after 6 days of incubation period. It was well in close agreement with the predicated value obtained by RSM model yield 82.67 ± 0.04 (%). Analysis of variance (ANOVA) showed F-value of 66.09, R2 of 0.9814, probability of <0.0001 and coefficient of variation of 0.97%, which confirmed the validity of the model. Degradation of BaP was confirmed using GC-MS and FTIR analysis. Kinetic study demonstrated that BaP degradation fitted first order kinetic model. To the best of our knowledge, this is the first report on statistical optimization of BaP degradation using yeast consortium in presence of ZnO nanoparticles and produced biosurfactant.