Fermentation Optimization for Co-production of Postbiotics by Bifidobacterium lactis BB12 in Cheese Whey

Abstract

Bioactive molecules, with health-beneficial effects and functional activity on the human, are called “postbiotics”, produced by probiotic bacteria. In this study, co-production of conjugated linoleic acid (CLA), exopolysaccharides (EPSs), and bacteriocins (BACs) by Bifidobacterium lactis BB12 in supplemented cheese whey was optimized using Box–Behnken design. Yeast extract concentration had a significant effect on all responses except EPSs. The temperature significantly affected the production of CLA and the inhibition zone (p < 0.05). The incubation time had significant effects on CLA, EPSs, and BACs production (p < 0.05). Desirability functions performed to the optimization of multiple responses by maximization of CLA, EPSs and inhibition zone. Optimum conditions of CLA, EPSs, and BACs co-production were as follows: incubation temperature 38 °C, incubation time 28 h, and yeast extract concentration 2.5%. Fourier transform infrared spectroscopy was used to analyze functional groups of postbiotics. Gas chromatography, thin-layer chromatography, and SDS-PAGE were used to analyze CLA isomers, EPSs monosaccharides composition, and BACs molecular weight, respectively. Co-production of CLA, EPSs, and BACs by B. lactis BB12 in dairy effluent, as a cultivation medium, optimized successfully in this study.