Hydroxypropyl celluloses(HPC) were homogenously synthesized by the reaction of cellulose with propylene oxide in NaOH/urea aqueous solution.Water-soluble HPC with molar degree of substitution(MSNMR) in the range of 0....Hydroxypropyl celluloses(HPC) were homogenously synthesized by the reaction of cellulose with propylene oxide in NaOH/urea aqueous solution.Water-soluble HPC with molar degree of substitution(MSNMR) in the range of 0.52~0.78 was prepared from microcrystalline cellulose,cotton linters,and spruce sulfite pulp.The structure of the HPC samples was characterized by means of FT-IR,NMR,gas chromatography(GC),and size exclusion chromatography(SEC) analyses.Three types of cellulose samples with different molecular weights were found to dissolve well in the NaOH/urea solvent with no obvious differences in reactivity and regioselectivity.The relative reactivity of hydroxyl groups in the glycosyl unit was in the following order:O-6>O-2>O-3.In addition,the results of the study indicated that the tandem reaction during hydroxypropylation could be ignored.展开更多
Owing to its subtropical or tropical environment and climate,South China is home to unique agricultural crops such as sugar cane,pineapple,banana,cassava,and rice,which generate a large amount of lignocellulosic agric...Owing to its subtropical or tropical environment and climate,South China is home to unique agricultural crops such as sugar cane,pineapple,banana,cassava,and rice,which generate a large amount of lignocellulosic agricultural wastes during agricultural as well as associated industrial processing.The efficient utilization of these wastes will have a significant impact on the economy and sustainable development of South China.This paper reviews the research investigations conducted both in China and elsewhere on the conversion of wastes from these subtropical or tropical agricultural crops into useful chemicals,energy,and biomaterials.The goal of this paper is to promote and summarize the extensive investigations on these agricultural wastes for the development of biorefinery.展开更多
Amphiphilic starch derivatives with high content of functional groups were prepared from potato starch using a one-pot synthesis method with a single reaction medium for the entire procedure. Potato starch was benzyla...Amphiphilic starch derivatives with high content of functional groups were prepared from potato starch using a one-pot synthesis method with a single reaction medium for the entire procedure. Potato starch was benzylated, followed by the introduction of hydroxypropyltrimethylammonium(HPMA) moieties without the purification of intermediates. The synthesis was performed under heterogeneous conditions, leading to the formation of benzyl 2-hydroxypropyltri methylammonium starch chloride(BnHPMAS) with a total degree of substitution(DS) of up to 1.4. This process improved the efficiency of the preparation of amphiphilic starch derivatives and reduced the time and resources consumed by avoiding a separation process and purification of the intermediate compounds.The DS of BnHPMAS was in the range of 0.36 to 1.4, which could be tuned by varying the molar ratio of the reagents to repeating unit or by changing the reaction temperature, time, and medium. The structure of the amphiphilic starches was characterized using elemental analysis, size exclusion chromatography,fourier transform infrared spectroscopy(FT-IR), and nuclear magnetic resonance(NMR) spectroscopy. Moreover, the surface tension and turbidity of the solutions of the products were measured for their potential application in the removal of dissolved and colloidal substances in paper cycling water.展开更多
2D ^13C-^1H HSQC NMR spectroscopy of acetylated cell walls in solution gives a detailed fingerprint that can be used to assess the chemical composition of the complete wall without extensive degradation. We demonstrat...2D ^13C-^1H HSQC NMR spectroscopy of acetylated cell walls in solution gives a detailed fingerprint that can be used to assess the chemical composition of the complete wall without extensive degradation. We demonstrate how multivariate analysis of such spectra can be used to visualize cell wall changes between sample types as high-resolution 2D NMR loading spectra. Changes in composition and structure for both lignin and polysaccharides can subsequently be interpreted on a molecular level. The multivariate approach alleviates problems associated with peak picking of overlapping peaks, and it allows the deduction of the relative importance of each peak for sample discrimination. As a first proof of concept, we compare Populus tension wood to normal wood. All well established differences in cellulose, hemicellulose, and lignin compositions between these wood types were readily detected, confirming the reliability of the multivariate approach, In a second example, wood from transgenic Populus modified in their degree of pectin methylesterification was compared to that of wild-type trees. We show that differences in both lignin and polysaccharide composition that are difficult to detect with traditional spectral analysis and that could not be a priori predicted were revealed by the multivariate approach. 2D NMR of dissolved cell wall samples combined with multivariate analysis constitutes a novel approach in cell wall analysis and provides a new tool that will benefit cell wall research.展开更多
The biosynthesis of cellulose,lignin,and hemicelluloses in plant secondary cell walls(SCWs)is regulated by a hierarchical transcriptional regulatory network.This network features orthologous transcription factors shar...The biosynthesis of cellulose,lignin,and hemicelluloses in plant secondary cell walls(SCWs)is regulated by a hierarchical transcriptional regulatory network.This network features orthologous transcription factors shared between poplar and Arabidopsis,highlighting a foundational similarity in their genetic regulation.However,knowledge on the discrepant behavior of the transcriptional-level molecular regulatory mechanisms between poplar and Arabidopsis remains limited.In this study,we investigated the function of PagMYB128 during wood formation and found it had broader impacts on SCW formation compared to its Arabidopsis ortholog,AtMYB103.Transgenic poplar trees overexpressing PagMYB128 exhibited significantly enhanced xylem development,with fiber cells and vessels displaying thicker walls,and an increase in the levels of cellulose,lignin,and hemicelluloses in the wood.In contrast,plants with dominant repression of PagMYB128 demonstrated the opposite phenotypes.RNA sequencing and reverse transcription–quantitative polymerase chain reaction showed that PagMYB128 could activate SCW biosynthetic gene expression,and chromatin immunoprecipitation along with yeast one-hybrid,and effector–reporter assays showed this regulation was direct.Further analysis revealed that PagSND1(SECONDARY WALL-ASSOCIATED NAC-DOMAIN PROTEIN1)directly regulates PagMYB128 but not cell wall metabolic genes,highlighting the pivotal role of PagMYB128 in the SND1-driven regulatory network for wood development,thereby creating a feedforward loop in SCW biosynthesis.展开更多
文摘Hydroxypropyl celluloses(HPC) were homogenously synthesized by the reaction of cellulose with propylene oxide in NaOH/urea aqueous solution.Water-soluble HPC with molar degree of substitution(MSNMR) in the range of 0.52~0.78 was prepared from microcrystalline cellulose,cotton linters,and spruce sulfite pulp.The structure of the HPC samples was characterized by means of FT-IR,NMR,gas chromatography(GC),and size exclusion chromatography(SEC) analyses.Three types of cellulose samples with different molecular weights were found to dissolve well in the NaOH/urea solvent with no obvious differences in reactivity and regioselectivity.The relative reactivity of hydroxyl groups in the glycosyl unit was in the following order:O-6>O-2>O-3.In addition,the results of the study indicated that the tandem reaction during hydroxypropylation could be ignored.
基金support from China Postdoctoral Science Foundation(2016M590783)the Foundation of Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education of China(KF2015013)
文摘Owing to its subtropical or tropical environment and climate,South China is home to unique agricultural crops such as sugar cane,pineapple,banana,cassava,and rice,which generate a large amount of lignocellulosic agricultural wastes during agricultural as well as associated industrial processing.The efficient utilization of these wastes will have a significant impact on the economy and sustainable development of South China.This paper reviews the research investigations conducted both in China and elsewhere on the conversion of wastes from these subtropical or tropical agricultural crops into useful chemicals,energy,and biomaterials.The goal of this paper is to promote and summarize the extensive investigations on these agricultural wastes for the development of biorefinery.
基金financially supported by National Natural Science Foundation of China (No. 21774036)State Key Laboratory of Pulp and Paper Engineering (No. 2017TS01)
文摘Amphiphilic starch derivatives with high content of functional groups were prepared from potato starch using a one-pot synthesis method with a single reaction medium for the entire procedure. Potato starch was benzylated, followed by the introduction of hydroxypropyltrimethylammonium(HPMA) moieties without the purification of intermediates. The synthesis was performed under heterogeneous conditions, leading to the formation of benzyl 2-hydroxypropyltri methylammonium starch chloride(BnHPMAS) with a total degree of substitution(DS) of up to 1.4. This process improved the efficiency of the preparation of amphiphilic starch derivatives and reduced the time and resources consumed by avoiding a separation process and purification of the intermediate compounds.The DS of BnHPMAS was in the range of 0.36 to 1.4, which could be tuned by varying the molar ratio of the reagents to repeating unit or by changing the reaction temperature, time, and medium. The structure of the amphiphilic starches was characterized using elemental analysis, size exclusion chromatography,fourier transform infrared spectroscopy(FT-IR), and nuclear magnetic resonance(NMR) spectroscopy. Moreover, the surface tension and turbidity of the solutions of the products were measured for their potential application in the removal of dissolved and colloidal substances in paper cycling water.
文摘2D ^13C-^1H HSQC NMR spectroscopy of acetylated cell walls in solution gives a detailed fingerprint that can be used to assess the chemical composition of the complete wall without extensive degradation. We demonstrate how multivariate analysis of such spectra can be used to visualize cell wall changes between sample types as high-resolution 2D NMR loading spectra. Changes in composition and structure for both lignin and polysaccharides can subsequently be interpreted on a molecular level. The multivariate approach alleviates problems associated with peak picking of overlapping peaks, and it allows the deduction of the relative importance of each peak for sample discrimination. As a first proof of concept, we compare Populus tension wood to normal wood. All well established differences in cellulose, hemicellulose, and lignin compositions between these wood types were readily detected, confirming the reliability of the multivariate approach, In a second example, wood from transgenic Populus modified in their degree of pectin methylesterification was compared to that of wild-type trees. We show that differences in both lignin and polysaccharide composition that are difficult to detect with traditional spectral analysis and that could not be a priori predicted were revealed by the multivariate approach. 2D NMR of dissolved cell wall samples combined with multivariate analysis constitutes a novel approach in cell wall analysis and provides a new tool that will benefit cell wall research.
基金supported by the National Key Research and Development Program of China(2021YFD2200900 to X.J.)funded by the DOE Great Lakes Bioenergy Research Center(DOE BER Office of Science DE-SC0018409)。
文摘The biosynthesis of cellulose,lignin,and hemicelluloses in plant secondary cell walls(SCWs)is regulated by a hierarchical transcriptional regulatory network.This network features orthologous transcription factors shared between poplar and Arabidopsis,highlighting a foundational similarity in their genetic regulation.However,knowledge on the discrepant behavior of the transcriptional-level molecular regulatory mechanisms between poplar and Arabidopsis remains limited.In this study,we investigated the function of PagMYB128 during wood formation and found it had broader impacts on SCW formation compared to its Arabidopsis ortholog,AtMYB103.Transgenic poplar trees overexpressing PagMYB128 exhibited significantly enhanced xylem development,with fiber cells and vessels displaying thicker walls,and an increase in the levels of cellulose,lignin,and hemicelluloses in the wood.In contrast,plants with dominant repression of PagMYB128 demonstrated the opposite phenotypes.RNA sequencing and reverse transcription–quantitative polymerase chain reaction showed that PagMYB128 could activate SCW biosynthetic gene expression,and chromatin immunoprecipitation along with yeast one-hybrid,and effector–reporter assays showed this regulation was direct.Further analysis revealed that PagSND1(SECONDARY WALL-ASSOCIATED NAC-DOMAIN PROTEIN1)directly regulates PagMYB128 but not cell wall metabolic genes,highlighting the pivotal role of PagMYB128 in the SND1-driven regulatory network for wood development,thereby creating a feedforward loop in SCW biosynthesis.
