Standardization of process parameters for enhanced prodigiosin production from wheat bran using Taguchi methodology

Prodigiosin finds tremendous application in the food industry owing to its physicochemical and non-toxic attributes. In the present investigation, microbial production of food color (prodigiosin) was done by Serratia marcescens NCIM 5246 under solid-state fermentation (SSF). For economical prodigiosin yield, initial substrate screening was conducted using agro-waste such as rice bran, wheat bran, orange peel powder, green gram husk and cane molasses. A maximum pigment yield of 1059.67 ± 1.53 µg/L was observed on wheat bran media. Further, Taguchi Design of the experiment (DOE) using Qualitek-4 software with bigger is better as quality attributes was done for process optimization. The Taguchi (DOE) comprised five independent variables, i.e., pH, temperature, substrate concentration, trace metal concentration, and inoculum size at two levels. The software deduced independent variables’ individual and interactive effects on product yield by performing an L8 orthogonal array (OA). The output variable (prodigiosin yield) was improved based on the S/N ratio. Under optimized cultural conditions maximum prodigiosin yield of 1320.2 ± 20 µg/L was obtained. The expected prodigiosin yield of 1386.60 µg/L showed a 95% resemblance with the actual yield, showed model validation, and 24.57% improvement in overall yield. The extracted pigment was purified by TLC and was characterized as prodigiosin by absorption spectroscopy and FTIR.