Enzymatic modification is an important approach to changing the structure and expanding industrial application of natural starch. In the process of starch modification, thermostable enzymes are favored owing to their ...Enzymatic modification is an important approach to changing the structure and expanding industrial application of natural starch. In the process of starch modification, thermostable enzymes are favored owing to their compatibility with higher reaction temperatures and lower required dosage. In this study, thermostable glucoamylase from Thermothelomyces thermophilus(TtGA) was heterologously expressed in Pichia pastoris, and its effects on the structure and physicochemical properties of raw corn starch were determined. The purified TtGA had a molecular weight of approximately 66 kDa, and its optimum reaction temperature and pH were 50 ℃ and 5.0, respectively. TtGA retained > 60% of its activity following treatment at 60 ℃ for 2 h and remained stable within a pH range of 4.0–7.0 for 6 h. The enzymatic modification of raw corn starch with TtGA led to 3% hydrolysis at 50 ℃ for 24 h. In comparison with natural raw corn starch, TtGA-modified starch had a smaller particle size with an unchanged crystalline structure, increased relative crystallinity, and amylose content.Scanning electronic observation showed that larger pores were formed on the surface of starch particles, and Fourier-transform infrared spectroscopy indicated that TtGA increased the degree of order in the raw corn starch.TtGA modification caused enhanced viscosity of the raw corn starch and altered the rheological properties with decreases in storage and loss moduli, as well as shear viscosity. Moreover, TtGA treatment enhanced the thermal characteristics of the raw corn starch, and decreased gelatinization enthalpy. This study provides detailed evidence for TtGA modification of raw corn starch, which would be helpful for its practical utilization in starch modification.展开更多
Lipase preparation from Aspergillus oryzae could act on ester bonds on the surface of poly （ethylene terephthalate） fibers and a possible hydrolytic product mono （2-hydroxyethyl） terephthalate was released. After ...Lipase preparation from Aspergillus oryzae could act on ester bonds on the surface of poly （ethylene terephthalate） fibers and a possible hydrolytic product mono （2-hydroxyethyl） terephthalate was released. After the iipase modification, there were more carboxyi groups on the treated poly （ethylene terephthalate） fabric surface that resulted in binding with more cationic dyes. Increased hydrophilicity and antistatic ability of poly （ethylene terephthalate） samples were found based on moisture regain, water contact angle and static half decay time.展开更多
OBJECTIVES:Soybean dreg is a by-product of soy milk processing,which contains high levels of soluble dietary fibre(SDF).In this study,we aimed to provide comprehensive processes of pre-treated extrusion for the improv...OBJECTIVES:Soybean dreg is a by-product of soy milk processing,which contains high levels of soluble dietary fibre(SDF).In this study,we aimed to provide comprehensive processes of pre-treated extrusion for the improving structure and properties of soybean dreg soluble dietary fibre(SDSDF),which would be a valuable approach to enhance physiological activity.METHODS:Here,we characteristic the functional role of SDSDF employing to extrusion pretreatment.Soybean dregs were pre-treated using the twin screw extrusion method followed by enzymatic modification using neutral protease,α-amylase,glucoamylase,and cellulose to produce SDSDF.The physical properties and antioxidant activity of SDSDF were investigated.RESULTS:The morphology and crystal structure of SDSDF were observed that,through extrusion processing and enzymatic modification,the SDSDF yield increased by 106.28%.Moreover,the surface structure showed block-shaped or reticular formations in the extruded SDSDF,and the size of block-shaped cells was about 10μm.Infrared spectroscopic analysis showed that a characteristic absorption peak of polysaccharide appeared at 1631 cm−1 during extrusion processing.However,after extrusion processing,decreased absorption peaks were observed for the extruded SDSDF.Furthermore,XRD analysis showed that the 2θdiffraction peak changed at 24.16°for the extruded SDSDF.CONCLUSIONS:The overall findings suggest that the water holding capacity(WHC),oil holding capacity(OHC),expansibility,and the water solubility were significantly decreased in extruded SDSDF.In addition,the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl(DPPH),-OH,O_(2)^(-),and the total reducing power were significantly improved,indicating that beneficial changes had taken place in the crystal structure of cellulose or hemicellulose to improve the physiological activity in extruded SDSDF.展开更多
Oil pollution is causing deleterious damage to aquatic ecosystems and human health.The utilization of agricultural waste such as corn stalk(CS)to produce biosorbents has been considered an ecofriendly and efficient ap...Oil pollution is causing deleterious damage to aquatic ecosystems and human health.The utilization of agricultural waste such as corn stalk(CS)to produce biosorbents has been considered an ecofriendly and efficient approach for removing oil.However,most previous studies focused on the modification of the whole CS,which is inefficient due to the heterogeneity of CS.In this study,corn stalk pith(CP),which has excellent amphipathic characteristics,was selected to prepare a high-efficiency oil sorbent by grafting dodecyl gallate(DG,a long-chain alkyl)onto CP surface lignin via laccase mediation.The modified biomass(DGCP)shows high hydrophobicity(water contact angle=140.2°)and superoleophilicity(oil contact angle=0°)and exhibits a high oil sorption capacity(46.43 g/g).In addition,DGCP has good stability and reusability for adsorbing oil from the aqueous phase.Kinetic and isotherm models and two-dimensional correlation spectroscopy integrated with FTIR analyses revealed that the main sorption mechanism involves the H-bond effect,hydrophobic effect and van der Waals force.This work provides an ecofriendly method to prepare oil sorbents and new insights into the mechanisms underlying the removal of spilled oil from wastewater.展开更多
As the second largest production material,starch has important value in textile,food,chemical and other fields.The shortcomings of natural starch can be solved,and its properties can be improved by modifying its struc...As the second largest production material,starch has important value in textile,food,chemical and other fields.The shortcomings of natural starch can be solved,and its properties can be improved by modifying its structure,developing original properties,or introducing new functions,making it more suitable for certain application requirements.At present,the methods of starch modification mainly include chemical,physical,and enzymatic modification.In comparison with the two traditional modification methods(chemical and physical modification)mentioned above,enzymatic modification has the advantages of mild conditions,high substrate selectivity,and high product safety,and it is the most ideal green modification method.In this paper,we present an overview of the modified starch by enzymatic structure design.The modification process and mechanism for granule starch and gelatinized starch are summarized.Further,the difficulties encountered in starch modification by enzymatic modification were also analyzed.These analyses could pave a way for understanding and broadening the preparation and applications of modified starch,and provide theoretical references for the utilization of amylase in starch modification.展开更多
In this study,pea starch was modified with maltogenicα-amylase and then its physicochemical properties,chain length distribution,and in vitro digestibility were examined.An analysis of the starch products resulting f...In this study,pea starch was modified with maltogenicα-amylase and then its physicochemical properties,chain length distribution,and in vitro digestibility were examined.An analysis of the starch products resulting from the maltogenicα-amylase treatment revealed a decrease in the molecular weight,an increase in the proportion of short chains[degree of polymerization(DP)<13],a decrease in the proportion of long chains(DP>13),and a decrease in viscosity,resulting in slower digestion.The results indicated that maltogenicα-amylase can selectively hydrolyzeα-1,4-andα-1,6-glycosides to some extent.Cleaving theα-1,4 linkage of starch facilitated the transfer of the non-reducing D-glucosyl residues of maltose,thereby generating anα-1,6 branch linkage.The reaction between maltogenicα-amylase and pea starch was affected by the reaction time and enzyme concentration.The maximum slowly digestible starch content(38.5%)was obtained by digesting samples with 60.0 ppm maltogenicα-amylase for 4.0 h.These findings demonstrate that modifying pea starch using maltogenicα-amylase can generate starch products with new branching structures conducive to slow digestion.展开更多
Phospholipase D(PLD)is an essential biocatalyst for the biological production of phosphatidylserine and phospholipid modification.However,the efficient heterologous expression of PLD is limited by its cell toxicity.In...Phospholipase D(PLD)is an essential biocatalyst for the biological production of phosphatidylserine and phospholipid modification.However,the efficient heterologous expression of PLD is limited by its cell toxicity.In this study,a PLD was secretory expressed efficiently in Bacillus subtilis with an activity around 100 U/mL.A secretory expression system containing the signal peptide SPEstA and the dual-promoter PHpaII-SrfA was estab-lished,and the extracellular PLD activity further reached 119.22 U/mL through scale-up fermentation,191.30-fold higher than that of the control.Under optimum reaction conditions,a 61.61%conversion ratio and 21.07 g/L of phosphatidylserine production were achieved.Finally,the synthesis system of PL derivates was established,which could efficiently synthesis novel PL derivates.The results highlight that the secretory expression system constructed in this study provides a promising PLD producing strain in industrial application,and laid the foundation for the biosynthesis of phosphatidylserine and other PL derivates.As far as we know,this work re-ports the highest level of extracellular PLD expression to date and the enzymatic production of several PL der-ivates for the first time.展开更多
基金supported by the National Key Research and Development Plan of China(grant number 2023YFC2604903)National Natural Science Foundation of China(grant number 22338013)+2 种基金Natural Science Foundation of Henan Province(grant number 242300421106)Henan Province Science and Technology Research and Development Plan Joint Fund Project(grant number 222103810063)Key Scientific and Technological Project of Education Department of Henan Province(grant number 23A210007).
文摘Enzymatic modification is an important approach to changing the structure and expanding industrial application of natural starch. In the process of starch modification, thermostable enzymes are favored owing to their compatibility with higher reaction temperatures and lower required dosage. In this study, thermostable glucoamylase from Thermothelomyces thermophilus(TtGA) was heterologously expressed in Pichia pastoris, and its effects on the structure and physicochemical properties of raw corn starch were determined. The purified TtGA had a molecular weight of approximately 66 kDa, and its optimum reaction temperature and pH were 50 ℃ and 5.0, respectively. TtGA retained > 60% of its activity following treatment at 60 ℃ for 2 h and remained stable within a pH range of 4.0–7.0 for 6 h. The enzymatic modification of raw corn starch with TtGA led to 3% hydrolysis at 50 ℃ for 24 h. In comparison with natural raw corn starch, TtGA-modified starch had a smaller particle size with an unchanged crystalline structure, increased relative crystallinity, and amylose content.Scanning electronic observation showed that larger pores were formed on the surface of starch particles, and Fourier-transform infrared spectroscopy indicated that TtGA increased the degree of order in the raw corn starch.TtGA modification caused enhanced viscosity of the raw corn starch and altered the rheological properties with decreases in storage and loss moduli, as well as shear viscosity. Moreover, TtGA treatment enhanced the thermal characteristics of the raw corn starch, and decreased gelatinization enthalpy. This study provides detailed evidence for TtGA modification of raw corn starch, which would be helpful for its practical utilization in starch modification.
基金Program for Changjiang Scholars and Inno■tive Research Team in University (IRT 0526)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘Lipase preparation from Aspergillus oryzae could act on ester bonds on the surface of poly （ethylene terephthalate） fibers and a possible hydrolytic product mono （2-hydroxyethyl） terephthalate was released. After the iipase modification, there were more carboxyi groups on the treated poly （ethylene terephthalate） fabric surface that resulted in binding with more cationic dyes. Increased hydrophilicity and antistatic ability of poly （ethylene terephthalate） samples were found based on moisture regain, water contact angle and static half decay time.
基金Natural Science foundation of Heilongjiang Province(C201124)Doctoral Scientific Research Project of Harbin University of Commerce(grant no.14LG16).
文摘OBJECTIVES:Soybean dreg is a by-product of soy milk processing,which contains high levels of soluble dietary fibre(SDF).In this study,we aimed to provide comprehensive processes of pre-treated extrusion for the improving structure and properties of soybean dreg soluble dietary fibre(SDSDF),which would be a valuable approach to enhance physiological activity.METHODS:Here,we characteristic the functional role of SDSDF employing to extrusion pretreatment.Soybean dregs were pre-treated using the twin screw extrusion method followed by enzymatic modification using neutral protease,α-amylase,glucoamylase,and cellulose to produce SDSDF.The physical properties and antioxidant activity of SDSDF were investigated.RESULTS:The morphology and crystal structure of SDSDF were observed that,through extrusion processing and enzymatic modification,the SDSDF yield increased by 106.28%.Moreover,the surface structure showed block-shaped or reticular formations in the extruded SDSDF,and the size of block-shaped cells was about 10μm.Infrared spectroscopic analysis showed that a characteristic absorption peak of polysaccharide appeared at 1631 cm−1 during extrusion processing.However,after extrusion processing,decreased absorption peaks were observed for the extruded SDSDF.Furthermore,XRD analysis showed that the 2θdiffraction peak changed at 24.16°for the extruded SDSDF.CONCLUSIONS:The overall findings suggest that the water holding capacity(WHC),oil holding capacity(OHC),expansibility,and the water solubility were significantly decreased in extruded SDSDF.In addition,the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl(DPPH),-OH,O_(2)^(-),and the total reducing power were significantly improved,indicating that beneficial changes had taken place in the crystal structure of cellulose or hemicellulose to improve the physiological activity in extruded SDSDF.
基金supported by the National Natural Science Foundation of China(Nos. 42007323, 42007107)the Natural Science Foundation of Guangdong Province, China(No. 2018A030313363)+2 种基金the Open Fund of the Guangdong Provincial Key Laboratory of Petrochemical Pollution Process and Control, China(No. 2018B030322017)the High-level Professionals and Innovative Teams, Shenzhen, China(Nos. SZIIT2019KJ024,SZIIT2019KJ007)the Shenzhen Science & Technology Project, China(No. SZIITWDZC2021A01)
文摘Oil pollution is causing deleterious damage to aquatic ecosystems and human health.The utilization of agricultural waste such as corn stalk(CS)to produce biosorbents has been considered an ecofriendly and efficient approach for removing oil.However,most previous studies focused on the modification of the whole CS,which is inefficient due to the heterogeneity of CS.In this study,corn stalk pith(CP),which has excellent amphipathic characteristics,was selected to prepare a high-efficiency oil sorbent by grafting dodecyl gallate(DG,a long-chain alkyl)onto CP surface lignin via laccase mediation.The modified biomass(DGCP)shows high hydrophobicity(water contact angle=140.2°)and superoleophilicity(oil contact angle=0°)and exhibits a high oil sorption capacity(46.43 g/g).In addition,DGCP has good stability and reusability for adsorbing oil from the aqueous phase.Kinetic and isotherm models and two-dimensional correlation spectroscopy integrated with FTIR analyses revealed that the main sorption mechanism involves the H-bond effect,hydrophobic effect and van der Waals force.This work provides an ecofriendly method to prepare oil sorbents and new insights into the mechanisms underlying the removal of spilled oil from wastewater.
基金supported by the Science and Technology Support Program(Modern Agriculture)of Jiangsu Province(BE2022323)the Natural Science Foundation of Jiangsu Province(BK20221074)+1 种基金the National First-class Discipline Program of Food Science and Technology(JUFSTR20180204)the Jiangsu province“Collaborative Innovation Center of Food Safety and Quality Control”industry development program.
文摘As the second largest production material,starch has important value in textile,food,chemical and other fields.The shortcomings of natural starch can be solved,and its properties can be improved by modifying its structure,developing original properties,or introducing new functions,making it more suitable for certain application requirements.At present,the methods of starch modification mainly include chemical,physical,and enzymatic modification.In comparison with the two traditional modification methods(chemical and physical modification)mentioned above,enzymatic modification has the advantages of mild conditions,high substrate selectivity,and high product safety,and it is the most ideal green modification method.In this paper,we present an overview of the modified starch by enzymatic structure design.The modification process and mechanism for granule starch and gelatinized starch are summarized.Further,the difficulties encountered in starch modification by enzymatic modification were also analyzed.These analyses could pave a way for understanding and broadening the preparation and applications of modified starch,and provide theoretical references for the utilization of amylase in starch modification.
基金supported by the Science and Technology Program under Taizhou Municipal Government(Project No.TN202005)the Science and Technology Program of Jiangsu Agri-animal Husbandry Vocational College(NSF2021ZR04)the Taizhou Municipal 311 Personnel Training Program(2017-1-42),and the Jiangsu Provincial Qing Lan Project.
文摘In this study,pea starch was modified with maltogenicα-amylase and then its physicochemical properties,chain length distribution,and in vitro digestibility were examined.An analysis of the starch products resulting from the maltogenicα-amylase treatment revealed a decrease in the molecular weight,an increase in the proportion of short chains[degree of polymerization(DP)<13],a decrease in the proportion of long chains(DP>13),and a decrease in viscosity,resulting in slower digestion.The results indicated that maltogenicα-amylase can selectively hydrolyzeα-1,4-andα-1,6-glycosides to some extent.Cleaving theα-1,4 linkage of starch facilitated the transfer of the non-reducing D-glucosyl residues of maltose,thereby generating anα-1,6 branch linkage.The reaction between maltogenicα-amylase and pea starch was affected by the reaction time and enzyme concentration.The maximum slowly digestible starch content(38.5%)was obtained by digesting samples with 60.0 ppm maltogenicα-amylase for 4.0 h.These findings demonstrate that modifying pea starch using maltogenicα-amylase can generate starch products with new branching structures conducive to slow digestion.
基金supported by the National Key Research and Development Program of China(No.2021YFC2100900)the National Natural Science Foundation of China(No.32171261)+1 种基金the Natural Science Foundation of Jiangsu Province(No.BK20221082)the Fundamental Research Funds for the Central Universities(No.JUSRP21940).
文摘Phospholipase D(PLD)is an essential biocatalyst for the biological production of phosphatidylserine and phospholipid modification.However,the efficient heterologous expression of PLD is limited by its cell toxicity.In this study,a PLD was secretory expressed efficiently in Bacillus subtilis with an activity around 100 U/mL.A secretory expression system containing the signal peptide SPEstA and the dual-promoter PHpaII-SrfA was estab-lished,and the extracellular PLD activity further reached 119.22 U/mL through scale-up fermentation,191.30-fold higher than that of the control.Under optimum reaction conditions,a 61.61%conversion ratio and 21.07 g/L of phosphatidylserine production were achieved.Finally,the synthesis system of PL derivates was established,which could efficiently synthesis novel PL derivates.The results highlight that the secretory expression system constructed in this study provides a promising PLD producing strain in industrial application,and laid the foundation for the biosynthesis of phosphatidylserine and other PL derivates.As far as we know,this work re-ports the highest level of extracellular PLD expression to date and the enzymatic production of several PL der-ivates for the first time.
