Advancing L-Lactic acid production through ultrasonic-assisted microbubbles-mediated ozonolysis of Eucheuma denticulatum hydrocolloid for enhanced D-galactose yield

Macroalgae conversion is receiving considerable attention in L-lactic acid (LLA) production as recent trends obtrude aggressive reduction in production costs. However, existing technologies suffer from low productivity. Indeed, this study proposed a proficient biorefinery process that facilitates sugar recovery and LLA production from Eucheuma denticulatum hydrocolloid (EDH). Ultrasonic-assisted microbubbles-mediated ozonolysis (UAMMO) treatment was applied under different process parameters to quantify the D-galactose recovery from EDH. The resulting D-galactose from UAMMO was subjected to L-LA fermentation under different nutrients to determine the variation of the LLA yield produced. Repeated-batch fermentation was established to enhance LLA production further. Through single-factor optimization of UAMMO treatment, a maximum D-galactose recovery (38.35 %) was attained at 90 °C for 105 min. The optimal LLA yield for fermentation was 90.28 % using 4 % (w/v) inoculum density of Lactobacillus acidophilus -14 with B vitamin complex. In addition, an average LLA yield of 89.28 % was sustained over three repeated cycles, indicating a promising avenue for macroalgae-based LLA production. These results contribute to the development of cost-effective and scalable biorefinery technologies for future bio-based chemical production. • Eucheuma denticulatum hydrocolloid as a feedstock for L-lactic acid production. • Ultrasonic-assisted microbubbles-mediated ozonolysis (UAMMO) boosts net galactose. • Integrated UAMMO treatment offers greener polysaccharide conversion. • Optimum UAMMO conditions were 90 °C and 105 min, yielding 38.35 % sugar recovery. • B vitamin complex enhanced the growth of Lactobacillus acidophilus -14.