Dataset Information

Impact of ammonium sulfite-based sequential pretreatment combinations on two distinct saccharifications of wheat straw.

ABSTRACT: The properties of lignocellulosic substrates obtained from different pretreatments have a big impact on downstream saccharification based on both the fungal cellulase system and the cellulosome-based whole-cell biocatalysis system. However the corresponding effect of these two distinct saccharification strategies has not been comparatively analyzed. In this work, three ammonium sulfite (AS)-based pretreatment combinations (i.e., AS + hydrothermal (HT) pretreatment, AS + xylanase (X) pretreatment, and HT + AS pretreatment) were conducted to treat wheat straw. The obtained pretreated substrates with different properties were saccharified using fungal cellulase or an engineered Clostridium thermocellum strain as the whole-cell biocatalyst, and the ability to release sugar was comparatively evaluated. It was found that for the whole-cell saccharification, the total sugar digestibility of AS + HT/X pretreated wheat straw was 10% higher than that of HT + AS pretreated wheat straw. However, for fungal cellulase-based saccharification, the enzymatic hydrolysis efficiency was less susceptible to the sequence of pretreatment combinations. Hence, the whole-cell biocatalysis system was more sensitive to substrate accessibility compared to the free enzymes. In addition, the characterization and analyses showed that AS + HT/X pretreatment could remove more lignin, generating a more accessible surface with a larger external surface and lower surface lignin coverage, compared to the HT + AS pretreatment. Therefore, the AS + HT/X pretreatment was more compatible with the cellulosome-based whole-cell saccharification.

SUBMITTER: Yu G

PROVIDER: S-EPMC9053470 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Impact of ammonium sulfite-based sequential pretreatment combinations on two distinct saccharifications of wheat straw.

Yu Guang G Liu Shiyue S Feng Xiaoyan X Zhang Yuedong Y Liu Chao C Liu Ya-Jun YJ Li Bin B Cui Qiu Q Peng Hui H

RSC advances 20200401 29

The properties of lignocellulosic substrates obtained from different pretreatments have a big impact on downstream saccharification based on both the fungal cellulase system and the cellulosome-based whole-cell biocatalysis system. However the corresponding effect of these two distinct saccharification strategies has not been comparatively analyzed. In this work, three ammonium sulfite (AS)-based pretreatment combinations (<i>i.e.</i>, AS + hydrothermal (HT) pretreatment, AS + xylanase (X) pretr ...[more]

PMID: 35521439

Similar Datasets

Project description:BackgroundIn this study, the dilute maleic acid pretreatment of wheat straw is optimized, using pretreatment time, temperature and maleic acid concentration as design variables. A central composite design was applied to the experimental set up. The response factors used in this study are: (1) glucose benefits from improved enzymatic digestibility of wheat straw solids; (2) xylose benefits from the solubilization of xylan to the liquid phase during the pretreatment; (3) maleic acid replenishment costs; (4) neutralization costs of pretreated material; (5) costs due to furfural production; and (6) heating costs of the input materials. For each response factor, experimental data were fitted mathematically. After data translation to euro/Mg dry straw, determining the relative contribution of each response factor, an economic optimization was calculated within the limits of the design variables.ResultsWhen costs are disregarded, an almost complete glucan conversion to glucose can be reached (90% from solids, 7%-10% in liquid), after enzymatic hydrolysis. During the pretreatment, up to 90% of all xylan is converted to monomeric xylose. Taking cost factors into account, the optimal process conditions are: 50 min at 170 degrees C, with 46 mM maleic acid, resulting in a yield of 65 euro/Mg (megagram = metric ton) dry straw, consisting of 68 euro/Mg glucose benefits (from solids: 85% of all glucan), 17 euro/Mg xylose benefits (from liquid: 80% of all xylan), 17 euro/Mg maleic acid costs, 2.0 euro/Mg heating costs and 0.68 euro/Mg NaOH costs. In all but the most severe of the studied conditions, furfural formation was so limited that associated costs are considered negligible.ConclusionsAfter the dilute maleic acid pretreatment and subsequent enzymatic hydrolysis, almost complete conversion of wheat straw glucan and xylan is possible. Taking maleic acid replenishment, heating, neutralization and furfural formation into account, the optimum in the dilute maleic acid pretreatment of wheat straw in this study is 65 euro/Mg dry feedstock. This is reached when process conditions are: 50 min at 170 degrees C, with a maleic acid concentration of 46 mM. Maleic acid replenishment is the most important of the studied cost factors.

Project description:BackgroundThe use of the enzymatic hydrolysis of lignocellulose with subsequent fermentation to ethanol provides a green alternative for the production of transportation fuels. Because of its recalcitrant nature, the lignocellulosic biomass must be pretreated before enzymatic hydrolysis. However, the pretreatment often results in the formation of compounds that are inhibitory for the enzymes or fermenting organism. Although well recognized, little quantitative information on the inhibition of individual cellulase components by identified inhibitors is available.ResultsStrong cellulase inhibitors were separated from the liquid fraction of the hydrothermal pretreatment of wheat straw. HPLC and mass-spectroscopy analyses confirmed that the inhibitors were oligosaccharides (inhibitory oligosaccharides, IOS) with a degree of polymerization from 7 to 16. The IOS are composed of a mixture of xylo- (XOS) and gluco-oligosaccharides (GOS). We propose that XOS and GOS are the fragments of the xylan backbone and mixed-linkage β-glucans, respectively. The IOS were approximately 100 times stronger inhibitors for Trichoderma reesei cellobiohydrolases (CBHs) than cellobiose, which is one of the strongest inhibitors of these enzymes reported to date. Inhibition of endoglucanases (EGs) by IOS was weaker than that of CBHs. Most of the tested cellulases and hemicellulases were able to slowly degrade IOS and reduce the inhibitory power of the liquid fraction to some extent. The most efficient single enzyme component here was T. reesei EG TrCel7B. Although reduced by the enzyme treatment, the residual inhibitory power of IOS and the liquid fraction was strong enough to silence the major component of the T. reesei cellulase system, CBH TrCel7A.ConclusionsThe cellulase inhibitors described here may be responsible for the poor yields from the enzymatic conversion of the whole slurries from lignocellulose pretreatment under conditions that do not favor complete degradation of hemicellulose. Identification of the inhibitory compounds helps to design better enzyme mixtures for their degradation and to optimize the pretreatment regimes to minimize their formation.

Dataset Information

Impact of ammonium sulfite-based sequential pretreatment combinations on two distinct saccharifications of wheat straw.

Publications

Impact of ammonium sulfite-based sequential pretreatment combinations on two distinct saccharifications of wheat straw.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets