(585i) L-Lactic Acid Production With Simultaneous Saccharification and Fermentation of Xylo-Oligosaccharides Waste Residue By Rhizopus Oryzae

Abstract: High substrate cost is one of the biggest challenges in fermentative L-lactic acid production. The waste residue of xylo-oligosaccharides (XOS) manufacturing process has been considered as an attractive alternative substrate for cost-effective L-lactic acid production because of its high enzymatic digestibility, various environmental benefits, and extremely low cost. Simultaneous saccharification and fermentation (SSF) technology is an advanced strategy for bioconversion of carbohydrate materials to lactic acid by coupling the enzymatic hydrolysis and microbial fermentation into a single step. In this study, L-lactic acid production from XOS waste residue by Rhizopus oryzae in a SSF process was investigated with a focus on improving substrate utilization efficiency and reducing production cost. Compared to separate hydrolysis and fermentation (SHF), a higher L-lactic acid titer and yield (22.39 g/L vs. 15.40 g/L and 44.77 g/100 g dry waste residue vs. 30.81 g/100 g dry waste residue) was achieved in the SSF process at a high temperature (40 °C) and 5 % substrate loading. When the substrate loading was increased to 10 %, 32.67 g/L L-lactic acid with a yield of 32.67 g/100 g dry waste residue was obtained in the SSF process. This is the first report on cost-effective L-lactic acid production from XOS waste residue by R. oryzae at a high temperature in a SSF process.