(600e) Co-Optimization of Lignin and Carbohydrate Processibility By Combinatorial Pretreatment

Lignocellulosic biorefinery has gained much attention worldwide in response to the challenges of energy demand and global climate change. However, the industrial implementation of biorefinery was often hindered by the unsatisfied pretreatment performance and low lignin conversion efficiency. In our study, combinatorial pretreatment strategies with low holding temperature were exploited to improve the fractionation performance of corn stover (CS). With the combinatorial pretreatment of 1% (w/w) H₂SO₄ followed by 50% (w/w) ethanol+1% (w/w) NaOH, glucose, xylose and galactose yields reached 91.4%, 72.5% and 79.9% in the whole fractionation process, respectively, which increased by 16.7%, 4.2% and 2.1% compared to those with single pretreatment. Lignin yield was 28.7% in solid residues and 70.2% in liquid fraction, which increased by 22.6% compared to that with single pretreatment. Lignin stream was used for polyhydroxyalkanoates (PHA) production by Pseudomonas strains. Combinatorial pretreatment obtained the highest PHA titer (483 mg/l), which was about 2.5 times higher than single pretreatment. NMR analysis revealed the mechanisms for improved lignin processibility by combinatorial pretreatment. Results suggested that combinational pretreatment removed the amorphous portion of CS, altered its structural and compositional properties, led to the increase of water holding capacity, and thus increased the fractionation, processibility, and conversion performance for both carbohydrate and lignin. Therefore, combinational pretreatment with low holding temperature substantially increased the fermentable sugars and fractionated lignin yield as well as the lignin conversion efficiency, and hence improved the biorefinery efficiency.