Characterization of Two New Endo-β-1,4-xylanases from Eupenicillium parvum 4–14 and Their Applications for Production of Feruloylated Oligosaccharides

Appl Microbiol Biotechnol

Sun

Lin

et al. 2020

Self Cite

Arabinofuranose substitutions on xylan are known to interfere with enzymatic hydrolysis of this primary hemicellulose. In this work, two novel α-l-arabinofuranosidases (ABFs), TtABF51A from Thielavia terrestris and EpABF62C from Eupenicillium parvum, were characterized and functionally analyzed. From sequences analyses, TtABF51A and EpABF62C belong to glycoside hydrolase (GH) families 51 and 62, respectively. Recombinant TtABF51A showed high activity on 4-nitrophenyl-α-l-arabinofuranoside (83.39 U/mg), low-viscosity wheat arabinoxylan (WAX, 39.66 U/mg), high-viscosity rye arabinoxylan (RAX, 32.24 U/mg), and sugarbeet arabinan (25.69 U/mg), while EpABF62C preferred to degrade arabinoxylan. For EpABF62C, the rate of hydrolysis of RAX (94.10 U/mg) was 2.1 times that of WAX (45.46 U/mg). The optimal pH and reaction temperature for the two enzymes was between 4.0 and 4.5 and 65 °C, respectively. Calcium played an important role in the thermal stability of EpABF62C. TtABF51A and EpABF62C showed the highest thermal stabilities at pH 4.5 or 5.0, respectively. At their optimal pHs, TtABF51A and EpABF62C retained greater than 80% of their initial activities after incubation at 55 °C for 96 h or 144 h, respectively. 1H NMR analysis indicated that the two enzymes selectively removed arabinose linked to C-3 of mono-substituted xylose residues in WAX. Compared with the singular application of the GH10 xylanase EpXYN1 from E. parvum, co-digestions of WAX including TtABF51A and/or EpABF62C released 2.49, 3.38, and 4.81 times xylose or 3.38, 1.65, and 2.57 times of xylobiose, respectively. Meanwhile, the amount of arabinose released from WAX by TtABF51A with EpXYN1 was 2.11 times the amount with TtABF51A alone. Key points • Two novel α-l-arabinofuranosidases (ABFs) displayed high thermal stability. • The thermal stability of GH62 family EpABF62C was dependent on calcium. • Buffer pH affects the thermal stability of the two ABFs. • Both ABFs enhance the hydrolysis of WAX by a GH10 xylanase.

Section: Methodsmentioning

confidence: 99%

Characterization and functional analysis of two novel thermotolerant α-l-arabinofuranosidases belonging to glycoside hydrolase family 51 from Thielavia terrestris and family 62 from Eupenicillium parvum

Appl Microbiol Biotechnol

Sun

Lin

et al. 2020

Self Cite

“…Commercial xylanase (X2629-100g, 470 BXU/g) was purchased from Sigma-Aldrich (Shanghai, China). The xylanase EpXYN1 (130 BXU/mL), EpXYN3 (722 BXU/ mL) and XynII (546 BXU/mL) were prepared according to our previous researches [43,44]. Other chemicals and reagents used in this study were of analytical grade.…”

Section: Methodsmentioning

confidence: 99%

Alkaline organosolv pretreatment of different sorghum stem parts for enhancing the total reducing sugar yields and p-coumaric acid release

Ding

2020

Biotechnol Biofuels

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Background: The sorghum stem can be divided into the pith and rind parts with obvious differences in cell type and chemical composition, thus arising the different recalcitrance to enzyme hydrolysis and demand for different pretreatment conditions. The introduction of organic solvents in the pretreatment can reduce over-degradation of cellulose and hemicellulose, but significance of organic solvent addition in pretreatment of different parts of sorghum stem is still unclear. Valorization of each component is critical for economy of sorghum biorefinery. Therefore, in this study, NaOH-ethanol pretreatment condition for different parts of the sorghum stem was optimized to maximize p-coumaric acid release and total reducing sugar recovery. Result: Ethanol addition improved p-coumaric acid release and delignification efficiency, but significantly reduced hemicellulose deconstruction in NaOH-ethanol pretreatment. Optimization using the response surface methodology revealed that the pith, rind and whole stem require different NaOH-ethanol pretreatment conditions for maximal p-coumaric acid release and xylan preservation. By respective optimal NaOH-ethanol pretreatment, the p-coumaric acid release yields reached 94.07%, 97.24% and 95.05% from pith, rind and whole stem, which increased by 8.16%, 8.38% and 8.39% compared to those of NaOH-pretreated samples. The xylan recoveries of pith, rind and whole stem reached 76.80%, 88.46% and 85.01%, respectively, which increased by 47.75%, 15.11% and 35.97% compared to NaOH pretreatment. Adding xylanase significantly enhanced the enzymatic saccharification of pretreated residues. The total reducing sugar yields after respective optimal NaOH-ethanol pretreatment and enzymatic hydrolysis reached 84.06%, 82.29% and 84.09% for pith, rind and whole stem, respectively, which increased by 29.56%, 23.67% and 25.56% compared to those of NaOH-pretreated samples. Considering the separation cost of the different stem parts, whole sorghum stem can be directly used as feedstock in industrial biorefinery. Conclusion: These results indicated that NaOH-ethanol is effective for the efficient fractionation and pretreatment of sorghum biomass. This work will help to understand the differences of different parts of sorghum stem under NaOH-ethanol pretreatment, thereby improving the full-component utilization of sorghum stem.

“…Commercial xylanase (X2629-100g) was purchased from Sigma-Aldrich (Shanghai, China). The xylanase EpXYN1, EpXYN3 and XynII were prepared according to our previous researches [29,30].…”

Section: Materials and Methods Materialsmentioning

confidence: 99%

Alkaline organosolv pretreatment of different sorghum stem parts for enhancing the total reducing sugar yields and p-coumaric acid release

Ding

2020

Preprint

Self Cite

Background : The sorghum stem can be divided into the pith and rind parts with obvious differences in cell type and chemical composition, thus arising the different recalcitrance to enzyme hydrolysis and demand for different pretreatment conditions. The introduction of organic solvents in the pretreatment can reduce over-degradation of cellulose and hemicellulose, but significance of solvent addition in pretreatment of different parts of sorghum stem is still unclear. Valorization of each component is critical for economy of sorghum biorefinery. Therefore, in this study, NaOH-ethanol pretreatment condition for different parts of the sorghum stem was optimized in order to maximize pcoumaric acid release and total reducing sugar recovery.Result: Ethanol addition improved p -coumaric acid release and delignification efficiency, but significantly reduced hemicellulose deconstruction in NaOH-ethanol pretreatment. The pith and rind require different NaOH-ethanol pretreatment conditions for maximal p -coumaric acid release and xylan preservation. The p -coumaric acid release yields by optimized NaOH-ethanol pretreatment reached 94.07%, 97.24% and 95.05% from pith, rind and whole stem, respectively, which increased by 8.16%, 8.38% and 8.39% compared to those of NaOH pretreated samples. Comparatively, xylan was more resistant to be dissolved from the rind than from the pith in the same NaOH-ethanol conditions. Adding xylanase significantly enhanced the enzymatic saccharification of pretreated residues. The total reducing sugar yields after NaOH-ethanol pretreatment and enzymatic hydrolysis reached 84.06%, 82.29% and 84.09% for pith, rind and whole stem, respectively, which increased by 29.56%, 23.67% and 25.56% compared to those of NaOH pretreated samples.Conclusion: These results indicated that NaOH-ethanol is effective for the efficient fractionation and pretreatment of sorghum biomass. This work will help to understand the differences of different parts of sorghum stem under NaOH-ethanol pretreatment, thereby improving the full-component utilization of sorghum stem. Keywords: Sorghum stem; NaOH-ethanol pretreatment; p -coumaric acid; enzymatic hydrolysis. Background Lignocellulosic biomass is an important feedstock for the production of biofuels and biobased 3 chemical products [1]. Cellulose, hemicellulose and lignin are the main biochemical components of lignocellulose. These three components are strongly intermeshing and bonded together (covalently or non-covalently) to form lignocellulosic matrix. Structural features make lignocellulosic biomass difficult to be deconstructed and digested, and result in relatively low digestibility of lignocellulosic feedstock [2]. In order to improve the enzymatic digestibility of lignocellulosic biomass, various pretreatment methods have been investigated based on the properties of each lignocellulosic feedstock [3]. Common pretreatment methods include acid treatment [4], alkali treatment [5], organosolv treatment [6], automated hydrolysis treatment [7], steam explosion treatment ...