Enhanced enzymatic hydrolysis and hydrogen production of sugarcane bagasse pretreated by peroxyformic acid.

Pretreatment plays a key role in biofuel production from lignocellulosic biomass. In this study, the main factors of peroxyformic acid (PA) pretreatment were optimized in the light of enzymolysis efficiency and composition analysis of pretreated sugarcane bagasse (SCB). Lignin was significantly removed (59.0%) and a complete saccharification level (103.6%) was obtained for the pretreated SCB with slight cellulose loss (9.2%) under the optimized pretreatment conditions. The effects of PA pretreatment on the structural characteristics of SCB were also studied and the digestibility of pretreated SCB was also evaluated by dark fermentative hydrogen production with an enriched anaerobic cellulolytic microbial consortium MC1. The hydrogen production increased by 195.5% (based on initial SCB) and the abundance of dominant hemicellulose-degradation genus Thermoanaerobacterium increased from 23.8% to 40.2% due to the remaining and accessible hemicellulose in PA pretreated SCB.

Bu J ，Wang YT ，Deng MC ，Zhu MJ ... -  《-》

Investigation of choline chloride-formic acid pretreatment and Tween 80 to enhance sugarcane bagasse enzymatic hydrolysis.

In this study, a pretreatment that consisting of choline chloride (ChCl) and formic acid (FA) were performed to improve sugarcane bagasse (SCB) enzymatic hydrolysis. Results showed that the ChCl-FA pretreatment exhibited an extraordinary ability to selectively extract hemicellulose (~95.6%) and degrade a large number of lignin (~72.6%) at 110 °C for 120 min, which enhanced the enzymatic hydrolysis of pretreated SCB. Besides, the impact of various additives on pretreated substrate enzymatic hydrolysis confirmed that Tween 80 was the best enzymatic additive, which could significantly improve the glucose produced from pretreated SCB and remarkably reduce the hydrolysis time (from 72 h to 48 h) and enzyme dosage (from 20 FPU/g pretreated solid to 10 FPU/g pretreated solid). In summary, the coupling of ChCl-FA pretreatment and Tween 80 exhibited a promising way to enhance the sugar release from SCB.

Ling R ，Wu W ，Yuan Y ，Wei W ，Jin Y ... -  《-》

The sequential Fenton oxidation and sulfomethylation pretreatment for alleviating the negative effects of lignin in enzymatic saccharification of sugarcane bagasse.

The sugarcane bagasse (SCB) was pretreated by the sequential Fenton oxidation and sulfomethylation pretreatment (FSP) for reducing the lignin inhibition in enzymatic saccharification. The FSP showed the delignification of 67.76% and the glucan retention in pretreated solid of 97.81%. Compared with sulfomethylation pretreated SCB (SP-SCB), the lignin surface coverage and surface hydrophobicity of FSP-SCB decreased by 1.84 and 4.84 times, respectively, led to enzymatic accessibility increased by 20%. Using the cellulase loading of 20 FPU/g glucan, the 72 h yields of glucose and xylose were 76.24% and 64.83%, respectively, which was 1.3-2.0 times higher than that of sulfomethylation treated SCB alone. Fenton oxidative reaction as a pre-step will help sulfomethyl group to easily and more introduce on aromatic ring, thereby accelerating the delignification.

Ying W ，Xu G ，Yang H ，Shi Z ，Yang J ... -  《-》

Lignin prepared from different alkaline pretreated sugarcane bagasse and its effect on enzymatic hydrolysis.

Sugarcane bagasse (SCB) was pretreated by sodium hydroxide (SH), alkaline ethanol (AE) and alkaline hydrogen peroxide (AHP), and the solid residue with similar lignin content after different pretreatment was selected. Enzymatic saccharification with different substrates was performed at 2%, 10%, and 20% (w/v) solid loading. After that, the lignin from different substrate was extracted and its structure was characterized. Furthermore, the adsorption capability of isolated lignin to cellulase and its effect on enzymatic hydrolysis were studied. The results showed that, as the substrate content increased from 2% (w/v) to 20% (w/v), the glucose yield after digestion of SH, AE, and AHP pretreated SCB reduced by 41.8%, 35.4%, and 28.7%, respectively. The inhibitory effect of different prepared lignin on the digestibility of Avicel was as follows, SH pretreated lignin (SHL) > cellulase enzymatic hydrolysis lignin (CEL) > AE pretreated lignin (AEL) > AHP pretreated lignin (AHPL), which exhibited positive correlation with its non-productive adsorption capability to cellulase. Lignin samples with low negative zeta potential, high hydrophobicity and high ration of syringyl (S) to guaiacyl (G) were unfavorable for the enzymatic saccharification of cellulose.

Xu C ，Zhang J ，Zhang Y ，Guo Y ，Xu H ，Liang C ，Wang Z ，Xu J ... -  《-》

Comprehensive understanding of enzymatic saccharification of Betaine:Lactic acid-pretreated sugarcane bagasse.

Green solvents, especially deep eutectic solvents (DESs), are widely applied to pretreat biomass for enhancing its enzymatic hydrolysis. In this work, lactic acid was selected as the hydrogen-bond-donor to prepare Betaine-base DES (Betaine:LA), The DES was utilized to pretreat sugarcane bagasse (SCB) at 160 ℃ for 80 min (severity factor LogR0 = 3.67). The influences of Betaine:LA treatment on the chemical composition, crystal and microstructure structure of cellulose, and cellulase digestion were investigated. The results showed that the lignin (47.1%) and xylan (44.6%) were removed, the cellulase digestibility of Betaine:LA-treated SCB was 4.2 times that of the raw material. This improved efficiency was attributed to the enhanced accessibility of cellulose, the weakened surface area of lignin, the declined hydrophobicity, and the decreased crystallinity of cellulose. Several compelling linear correlations were fitted between enzymatic hydrolysis and these alterations of physicochemical features, comprehensively understanding enzymatic saccharification of Betaine:LA-pretreated SCB.

Chen Y ，Ma C ，Tang W ，He YC ... -  《-》