Intensification of Poly(β-l-malic acid) Production from Cane Molasses via an Integrated Strategy: Pretreatment...

Cane molasses, an abundant low-cost sugar industry byproduct, is a promising feedstock for high-value poly(β-l-malic acid) (PMLA) production, but raw utilization is hindered by inhibitors (high osmotic pressure, pigments, pectin), leading to a mere 7.6 g/L PMLA yield (≈11% of glucose) in 7.5 L fermenters. This study proposes an integrated strategy combining advanced pretreatment and immobilization. A novel sequential SADE pretreatment (dilution, acidification, decolorization, and enzymatic hydrolysis) eliminated inhibitors while preserving fermentable sugars. Coupled with fed-batch fermentation (total sugar 800 g), it achieved 54.7 g/L PMLA, 82.85 g/L biomass, and 0.76 g/(L·h) productivity. Further, immobilizing Aureobasidium melanogenum ipe-1 on luffa sponge enabled three repeated batches with an average 56.71 g/L PMLA yield, 11.5% higher than free-cell fermentation.