Dual effect of seawater as a chemical and solvent in the pretreatment, saccharification and fermentation of corn cobs for lactic acid production

This study developed and optimized a seawater (SW)-based pretreatment to enhance sugar recovery from corn cobs (CC) (SW-CC). Additionally, the Lactobacillus plantarum microbial growth and lactic acid (LA) production kinetics were comparatively assessed utilizing the logistics and modified Gompertz models, respectively, across three bioprocess conditions: (1) SW-CC in supplemented seawater (s-SW), (2) SW-CC in supplemented deionized water (s-W), and (3) SW-CC in deionized water supplemented with conventional MRS replacing pure glucose (sMRS-W). The optimized SW-CC pretreatment yielded a reducing sugar and glucose yield of 0.277 g/g ± 0.001 and 0.172 g/g ± 0.02 g/g, respectively. The s-SW system exhibited the highest maximum specific growth rate (µ max = 0.342 h −1 ), indicating favourable microbial proliferation in the SW-based medium. Although the s-W process achieved the highest maximum LA concentration (P m = 5.545 g/L), the s-SW process followed closely with a P m of 4.031 g/L, highlighting its comparable fermentative performance. This research provides the basis for implementing, abundant and innovative sources such as seawater for both the pretreatment and fermentation stages during bioproduct formation, thus reducing the reliance on chemicals and freshwater in lignocellulosic biorefinery processes. • Seawater (SW) and corn cob valorization for sustainable lactic acid (LA) production. • SW-based SSF bioprocess (s-SW) achieved the highest µ max (0.342 h −1 ). • s-SW produced a comparable highest maximum LA concentration result (4.031 g/L). • Demonstrated SW as a viable replacement for freshwater in LA biorefineries. • Eliminating freshwater and costly media enhances overall bioprocess feasibility.