scholarly journals Unrevealing Model Compounds of Soil Conditioners Impacts on the Wheat Straw Autohydrolysis Efficiency and Enzymatic Hydrolysis

2020 ◽  
Author(s):  
Xinxing Wu ◽  
Wei Tang ◽  
Chen Huang ◽  
Caoxing Huang ◽  
Chenhuan Lai ◽  
...  

Abstract Background: Soil-derived exogenous ash (EA) poses a challenge toward lignocellulosics autohydrolysis due to its buffering capacity. Previous works focusing on this phenomenon have failed to also investigate the role that soluble salts, and organic matter plays in this system. Herein, sodium phosphate and sodium humate were employed as model buffering compounds representing soluble salts and organic matter and dosed into a de-ashed wheat straw (DWS) autohydrolysis process to show the potential impacts of WS attached soil conditioners on the WS autohydrolysis efficiency which would further affect the enzymatic digestibility of autohydrolyzed WS.Results: Results showed that with the increasing loadings of sodium phosphate and sodium humate resulted in elevated pH values (from 4.0 to 5.1 and from 4.1 to 4.7, respectively). Meanwhile, the reductions of xylan removal yields from ~ 84.3–61.4% to 72.3–53.0% by loading (1 ~ 30 g/L) sodium phosphate and sodium humate during WS autohydrolysis lead to a significant decrease of cellulose accessibilities which finally lead to a reduction of the enzymatic digestibility of autohydrolyzed WS from ~ 75.4–77.2% to 47.3–57.7%.Conclusion: The existence of different types soil conditioner model compounds result in various component fractions from autohydrolyzed WS in the process of autohydrolysis. A lack of sufficient xylan removal was found to drive the significant decrease in enzymatic accessibility. The results demonstrated the various effects of two typical tested soil conditioners on WS autohydrolysis and enzymatic hydrolysis.

2020 ◽  
Author(s):  
Xinxing Wu ◽  
Wei Tang ◽  
Chen Huang ◽  
Caoxing Huang ◽  
Chenhuan Lai ◽  
...  

Abstract Background: Soil-derived exogenous ash (EA) poses a challenge toward lignocellulosics autohydrolysis due to its buffering capacity. Previous works focusing on this phenomenon have failed to also investigate the role that soluble salts, and organic matter plays in this system. Herein, sodium phosphate and sodium humate were employed as model buffering compounds representing soluble salts and organic matter and dosed into a de-ashed wheat straw (DWS) autohydrolysis process to show the potential impacts of WS attached soil conditioners on the WS autohydrolysis efficiency which would further affect the enzymatic digestibility of autohydrolyzed WS.Results: Results showed that with the increasing loadings of sodium phosphate and sodium humate resulted in elevated pH values (from 4.0 to 5.1 and from 4.1 to 4.7, respectively). Meanwhile, the reductions of xylan removal yields from ~84.3-61.4% to 72.3-53.0% by loading (1~30 g/L) sodium phosphate and sodium humate during WS autohydrolysis lead to a significant decrease of cellulose accessibilities which finally lead to a reduction of the enzymatic digestibility of autohydrolyzed WS from ~75.4-77.2% to 47.3-57.7%.Conclusion: The existence of different types soil conditioner model compounds result in various component fractions from autohydrolyzed WS in the process of autohydrolysis. A lack of sufficient xylan removal was found to drive the significant decrease in enzymatic accessibility. The results demonstrated the various effects of two typical tested soil conditioners on WS autohydrolysis and enzymatic hydrolysis.


2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xinxing Wu ◽  
Wei Tang ◽  
Chen Huang ◽  
Caoxing Huang ◽  
Chenhuan Lai ◽  
...  

2021 ◽  
Author(s):  
Youshan Sun ◽  
Xuyang Zhang ◽  
Fei Wang ◽  
Meiyan Wang

Abstract Calcium peroxide (CaO2) pretreatment was employed to remove lignin and subsequently facilitate enzymatic digestibility of wheat straw. An optimal condition was obtained at 130°C for 10 min with 0.35 g CaO2/g dried material of wheat straw and a 1:8 solid-liquid ratio. Under this condition, 57.8% of initial lignin, 7.2% of initial glucan, and 30.6% of initial xylan were removed from CaO2 pretreatment, respectively, meanwhile, a glucose recovery of 90.6 % and a xylose recovery of 65.9 % were obtained from the subsequent enzymatic hydrolysis of treated wheat straw, respectively. CaO2 pretreatment was proved to be a very effective method in delignification and improving enzymatic digestibility. Compared to raw material, the complex structure of lignocellulose was drastically disrupted with a wide emergence of scaly bulges and fully exposed microfibers, which still retained in the solid.


2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Wei Tang ◽  
Xinxing Wu ◽  
Chen Huang ◽  
Caoxing Huang ◽  
Chenhuan Lai ◽  
...  

Abstract Background The acid buffering capacity of high free ash in waste wheat straw (WWS) has been revealed to be a significant hindrance on the efficiency of autohydrolysis pretreatment. Previous researches have mainly relied on washing to eliminate the influence of ash, and the underlying mechanism of the ash influencing was not extensively investigated. Presently, studies have found that cations can destroy the acid buffering capacity of ash through cation exchange. Herein, different cations were applied to presoak WWS with the aim to overcome the negative effects of ash on autohydrolysis efficiency, further improving its enzymatic digestibility. Results Results showed that cations can be adsorbed on the surface of the material by electrostatic adsorption to change the acid buffering capacity of WWS. The acid buffering capacity of 120 mM Fe2+ presoaked WWS is reduced from 226.3 mmol/pH-kg of original WWS to 79.3 mmol/pH-kg. This reduced the autohydrolysis pretreatment medium pH from 5.7 to 3.8 and promoted the removal of xylan from 61.7 to 83.7%. In addition, the enzymatic digestibility of WWS was enhanced from 49.7 to 86.3% by presoaking with 120 mM Fe2+ solution. The relationship between enzymatic accessibility and hydrophobicity with enzymatic digestibility of the autohydrolyzed WWS was analyzed. Conclusions The results showed that the acid buffering capacity of the high free ash was detrimental for the autohydrolysis efficiency of WWS. After WWS was presoaked with different cations, the acid buffering capacity of ash was weakened by cation exchange and electrostatic adsorption, which improved the autohydrolysis efficiency. The results expound that the enzymatic digestibility of WWS can be enhanced through presoaking to reduce the ash-influencing effect on autohydrolysis.


2010 ◽  
Vol 107 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Roozbeh Alinia ◽  
Samyar Zabihi ◽  
Feridun Esmaeilzadeh ◽  
Jamshid Fathi Kalajahi

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 487
Author(s):  
Dimitrios Ilanidis ◽  
Stefan Stagge ◽  
Leif J. Jönsson ◽  
Carlos Martín

Biochemical conversion of wheat straw was investigated using hydrothermal pretreatment, enzymatic saccharification, and microbial fermentation. Pretreatment conditions that were compared included autocatalyzed hydrothermal pretreatment at 160, 175, 190, and 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment at 160 and 190 °C. The effects of using different pretreatment conditions were investigated with regard to (i) chemical composition and enzymatic digestibility of pretreated solids, (ii) carbohydrate composition of pretreatment liquids, (iii) inhibitory byproducts in pretreatment liquids, (iv) furfural in condensates, and (v) fermentability using yeast. The methods used included two-step analytical acid hydrolysis combined with high-performance anion-exchange chromatography (HPAEC), HPLC, ultra-high performance liquid chromatography-electrospray ionization-triple quadrupole-mass spectrometry (UHPLC-ESI-QqQ-MS), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Lignin recoveries in the range of 108–119% for autocatalyzed hydrothermal pretreatment at 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment were attributed to pseudolignin formation. Xylose concentration in the pretreatment liquid increased with temperature up to 190 °C and then decreased. Enzymatic digestibility was correlated with the removal of hemicelluloses, which was almost quantitative for the autocatalyzed hydrothermal pretreatment at 205 °C. Except for the pretreatment liquid from the autocatalyzed hydrothermal pretreatment at 205 °C, the inhibitory effects on Saccharomyces cerevisiae yeast were low. The highest combined yield of glucose and xylose was achieved for autocatalyzed hydrothermal pretreatment at 190 °C and the subsequent enzymatic saccharification that resulted in approximately 480 kg/ton (dry weight) raw wheat straw.


Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 507
Author(s):  
Eduardo Troncoso-Ortega ◽  
Rosario del P. Castillo ◽  
Pablo Reyes-Contreras ◽  
Patricia Castaño-Rivera ◽  
Regis Teixeira Mendonça ◽  
...  

The objective of this study was to investigate structural changes and lignin redistribution in Eucalyptus globulus pre-treated by steam explosion under different degrees of severity (S0), in order to evaluate their effect on cellulose accessibility by enzymatic hydrolysis. Approximately 87.7% to 98.5% of original glucans were retained in the pre-treated material. Glucose yields after the enzymatic hydrolysis of pre-treated material improved from 19.4% to 85.1% when S0 was increased from 8.53 to 10.42. One of the main reasons for the increase in glucose yield was the redistribution of lignin as micro-particles were deposited on the surface and interior of the fibre cell wall. This information was confirmed by laser scanning confocal fluorescence and FT-IR imaging; these microscopic techniques show changes in the physical and chemical characteristics of pre-treated fibres. In addition, the results allowed the construction of an explanatory model for microscale understanding of the enzymatic accessibility mechanism in the pre-treated lignocellulose.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Wenqian Lin ◽  
Jinlai Yang ◽  
Yayue Zheng ◽  
Caoxing Huang ◽  
Qiang Yong

Abstract Background During the dilute acid pretreatment process, the resulting pseudo-lignin and lignin droplets deposited on the surface of lignocellulose and inhibit the enzymatic digestibility of cellulose in lignocellulose. However, how these lignins interact with cellulase enzymes and then affect enzymatic hydrolysis is still unknown. In this work, different fractions of surface lignin (SL) obtained from dilute acid-pretreated bamboo residues (DAP-BR) were extracted by various organic reagents and the residual lignin in extracted DAP-BR was obtained by the milled wood lignin (MWL) method. All of the lignin fractions obtained from DAP-BR were used to investigate the mechanism for interaction between lignin and cellulase using surface plasmon resonance (SPR) technology to understand how they affect enzymatic hydrolysis Results The results showed that removing surface lignin significantly decreased the yield for enzymatic hydrolysis DAP-BR from 36.5% to 18.6%. The addition of MWL samples to Avicel inhibited its enzymatic hydrolysis, while different SL samples showed slight increases in enzymatic digestibility. Due to the higher molecular weight and hydrophobicity of MWL samples versus SL samples, a stronger affinity for MWL (KD = 6.8–24.7 nM) was found versus that of SL (KD = 39.4–52.6 nM) by SPR analysis. The affinity constants of all tested lignins exhibited good correlations (r > 0.6) with the effects on enzymatic digestibility of extracted DAP-BR and Avicel. Conclusions This work revealed that the surface lignin on DAP-BR is necessary for maintaining enzyme digestibility levels, and its removal has a negative impact on substrate digestibility.


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