Efficient Conversion of Cane Molasses Towards High-Purity Isomaltulose and Cellular Lipid Using an Engineered Yarrowia lipolytica Strain in Fed-Batch Fermentation

Abstract

Cane molasses is one of the main by-products of sugar refineries, which is rich in sucrose. In this work, low-cost cane molasses was introduced as an alternative substrate for isomaltulose production. Using the engineered Yarrowia lipolytica, the isomaltulose production reached the highest (102.6 g L ⁻¹) at flask level with pretreated cane molasses of 350 g L ⁻¹ and corn steep liquor of 1.0 g L ⁻¹. During fed-batch fermentation, the maximal isomaltulose concentration (161.2 g L ⁻¹) was achieved with 0.96 g g ⁻¹ yield within 80 h. Simultaneously, monosaccharides were completely depleted, harvesting the high isomaltulose purity (97.4%) and high lipid level (12.2 g L ⁻¹). Additionally, the lipids comprised of 94.29% C ₁₆ and C ₁₈ fatty acids, were proved suitable for biodiesel production. Therefore, the bioprocess employed using cane molasses in this study was low-cost and eco-friendly for high-purity isomaltulose production, coupling with valuable lipids.