Fermentation mode and media effects on 1,3-propanediol and organic acids production using Levilactobacillus brevis PD20.100

1,3-Propanediol (PD) is a C3 diol with wide applications in biopolymers and personal care products. Microbial production of PD from crude glycerol (CG) has gained attention as a sustainable alternative to petrochemical routes, where yield and process cost are critical factors. In this study, the PD production potential of an adaptively evolved Levilactobacillus brevis PD20.100 was evaluated using fish protein hydrolysate (FPH), an industrial by-product of the fisheries sector, as a nitrogen source. Batch, fed-batch, and immobilized fermentation modes were investigated and compared with a conventional nutrient-rich modified MRS (mMRS) medium. Fermentation performance was assessed based on cell growth, substrate utilization, and formation of PD, lactic acid (LA), and acetic acid (AA). Batch fermentation with suspended cells in mMRS resulted in the highest PD titer of 39.75 g/L, while FPH-supported fermentation achieved a comparable PD concentration of 31.16 g/L. Although fed-batch and immobilized systems offered operational stability and reusability, they exhibited lower productivity. Overall, the results demonstrate that FPH can serve as a cost-effective and sustainable nitrogen source for microbial PD production, supporting the valorization of fish-processing by-products.