Hydrolysis pattern analysis of xylem tissues of woody plants pretreated with hydrogen peroxide and acetic acid: rapid saccharification of softwood for economical bioconversion

Abstract

Background Woody plants with high glucose content are alternative bioresources for the production of biofuels and biochemicals. Various pretreatment methods may be used to reduce the effects of retardation factors such as lignin interference and cellulose structural recalcitrance on the degradation of the lignocellulose material of woody plants. Results A hydrogen peroxide-acetic acid (HPAC) pretreatment was used to reduce the lignin content of several types of woody plants, and the effect of the cellulose structural recalcitrance on the enzymatic hydrolysis was analyzed. The cellulose structural recalcitrance and the degradation patterns of the wood fibers in the xylem tissues of Quercus acutissima (hardwood) resulted in greater retardation in the enzymatic saccharification than those in the tracheids of Pinus densiflora (softwood). In addition to the HPAC pretreatment, the application of supplementary enzymes (7.5 FPU cellulase for 24 h) further increased the hydrolysis rate of P. densiflora from 61.42 to 91.94% whereas the same effect was not observed for Q. acutissima. It was also observed that endoxylanase synergism significantly affected the hydrolysis of P. densiflora. However, this synergistic effect was lower for other supplementary enzymes. The maximum concentration of the reducing sugars produced from 10% softwood was 89.17 g L−1 after 36 h of hydrolysis with 15 FPU cellulase and other supplementary enzymes. Approximately 80 mg mL−1 of reducing sugars was produced with the addition of 7.5 FPU cellulase and other supplementary enzymes after 36 h, achieving rapid saccharification. Conclusion HPAC pretreatment removed the interference of lignin, reduced structural recalcitrance of cellulose in the P. densiflora, and enabled rapid saccharification of the woody plants including a high concentration of insoluble substrates with only low amounts of cellulase. HPAC pretreatment may be a viable alternative for the cost-efficient production of biofuels or biochemicals from softwood plant tissues.

Succinic acid production from softwood with genome‐edited Corynebacterium glutamicum using the CRISPR‐Cpf1 system

“…Cellulase was produced using the Rut-C30 strain of Trichoderma reesei. [22] The activity of the cellulase stock on filter paper was measured to be 50 FPU mL (high-performance liquid chromatography) analysis. [21,33] For fedbatch system, an initial 4% hydrolysate was prepared under the same conditions as mentioned above, with the exception of extending the reaction time to 120 h to reduce variation of sugar concentration.…”

“…[44,45] Furthermore, at the tissue level, the tracheid structures including pit, window-like pits, and lumen diameter provided a wider accessible surface for cellulases, leading to an increased hydrolysis rate. [28] The open structural cellulose surface of HPAC-pretreated pine can be saturated by hydrolytic enzymes such as Cel7A (cellobiohydrolase I) and Cel6A (cellobiohydrolase II), which together account for 68%-78% of the secretome of T. reesei Rut-C30. [46] These enzymes are responsible for releasing cellobiose from solid cellulose fibers.…”

“…Woody plants, including pine wood, exhibit greater recalcitrance compared to herbaceous agricultural biomass, such as corn stover, kenaf, rapeseed straw, and rice straw, when subjected to pretreatments such as popping and steam explosion. [21][22][23][24][25] Organosolv and dilute acid techniques are more effective for the hydrolysis of hardwoods (poplar and eucalyptus) than for softwoods (pine and spruce). [16,25] Sulfite pretreatment has been shown to improve hydrolysis rates in aspen, eucalyptus, spruce, and red pine.…”

A sustainable waste-to-protein system to maximise waste resource utilisation for developing food- and feed-grade protein solutions

“…lignocellulosic cell walls) into constituent monomers, in addition to releasing dissolved proteins and reducing sugars from the intracellular matrix. 116 Research into enzymatic hydrolysis of lignocellulosic waste has been detailed in previous reviews. 2,114,117,118 In brief, according to Modenbach and Nokes (2013) cellulases and xylanases are the most commonly adopted enzymes to degrade cellulose and xylan, respectively.…”

Organosolv pretreatment assisted by carbocation scavenger to mitigate surface barrier effect of lignin for improving biomass saccharification and utilization

“…In lignocellulosic biomass, cellulose and hemicellulose are considered as the economical constituents which are amenable to produce fermentable sugars and further be converted to biofuels and chemicals [ 3 , 4 ]. However, the presence of lignin in lignocellulosic biomass and the resulting complex lignocellulosic matrix make it highly resistant towards saccharification by microorganisms or enzymes to produce fermentable sugars [ 5 ]. Thereby, a pretreatment stage is always essential to open up lignocellulosic matrix by fractionating lignin and/or partial hemicellulose components, making cellulose more available to enzymatic attack [ 6 , 7 ].…”