Modeling of permeabilization process in Pseudomonas putida G7 for enhanced limonin bioconversion

A facile process of enhanced whole cell biotransformation to debitter the triterpenoid limonin in citrus juices was optimized in this work. To maximize bioconversion, permeabilization conditions were modeled using response surface methodology. A central composite rotatable design with four significant variables (concentration, temperature, pH, and treatment time) was employed. The second order polynomial equations with R (2) values above 0.9 showed good correspondence between experimental and predicted values. The concentration, temperature, pH, and treatment time as well as their interactions had significant effects (p < 0.001) on limonin bioconversion. The optimum operating conditions for permeabilization were observed at a Na(2)EDTA concentration of 1.5 mu M, treatment time of 15 min, temperature of 28 A degrees C, and pH 8. A maximum reduction of 76.71% in the limonin content was achieved within 150 min under selected conditions. The results are promising for refining permeabilization technique for whole cell biocatalysts thereby improving the debittering of citrus juices significantly.