(448g) [Keynote] Enhancing Prehydrolysates Fermentability By Adding Nucleophilic Amino Acids and Proteins in Biomass Pretreatment

Dilute acid pretreatment produced a considerable amount of carbonyl compounds in the biomass prehydrolysates, which significantly inhibited the sequential microbial fermentation. To reduce the release of carbonyl inhibitors, a new approach of pretreatment with amino acids and proteins has been developed to improve the fermentability of prehydrolysates. Cysteine (Cys), histidine (His), soy protein isolate (SPI) and bovine serum albumin (BSA) were added into dilute acid pretreatment of aspen (DAPA). The prehydrolysates were fermented by Saccharomyces cerevisiae, the glucose consumption rate in the prehydrolysates was increased from 0.32 g/L/h to 1.35, 3.22, 1.02 and 1.61 g/L/h, respectively. The substrates remaining after pretreatment were applied to enzymatic hydrolysis. Unexpectedly, it was observed that 72 h hydrolysis yields of DAPA-Cys and DAPA-His decreased from 71.35% (DAPA) to 63.93% and 28.11%, respectively. While, the 72 h hydrolysis yields of DAPA-SPI and DAPA-BSA increased to 75.04%, and 72.38%, respectively. The results showed that BSA was the most effective additives to enhance the prehydrolysate fermentability and enzymatic hydrolysis. It increased the ethanol productivity of prehydrolysates from 0.33 g/L/h (without addition) to 1.54 g/L/h. The final yield was promoted from 0.05 to 0.44 g/g glucose. In addition, total 22 potential inhibitors in prehydrolysates have been identified and quantified by gas chromatography-mass spectrometry (GC/MS). The results showed the addition of histidine in pretreatment reduced inhibitors much more than the addition of cysteine, SPI and BSA.