Resistant starch(RS)has attracted much researchers'attention because of its health-beneficial effects.Gut microbiota obviously shapes human health,but the effects of RS supplementation on the changes of human gut ...Resistant starch(RS)has attracted much researchers'attention because of its health-beneficial effects.Gut microbiota obviously shapes human health,but the effects of RS supplementation on the changes of human gut microbiota remain unclear.This observational meta-analysis aimed to reveal the effects of RS intake onα-diversity and composition of gut microbiota through meta-analysis.Two independent authors systematically searched articles from inception until February 2023 on four electronic databases.Twenty-four highly relevant trials were included conforming to Preferred Reporting Items for Systematic reviews and MetaAnalysis protocol,and a total of 816 individuals were included.Significant heterogeneity analyses revealed that RS intake notably decreased Shannon index(weighted mean difference(WMD):-0.11;95%confidence interval(CI):-0.21,-0.01),and stimulated the composition of health promoting bacteria genera,including Bifidobacterium(relative abundance:WMD:1.75;95%CI:0.39,3.11;bacterial populations:WMD:0.36;95%CI:0.04,0.69),Faecalibacterium(relative abundance:WMD:0.70;95%CI:0.20,1.20;fold change:effect size:0.91;95%CI:0.60,1.23),and Prevotella(relative abundance:WMD:0.35;95%CI:0.01,0.69).Taken together,the present study revealed that changes in the gut microbiota diversity and genera were correlated with RS supplementation,which may contribute to benefits in human health.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
1,4-α-Glucan branching enzyme(GBE;EC 2.4.1.18),which plays an important role in starch modification,has been mostly expressed in Escherichia coli.The application of GBE in food industry is limited by the low yield of...1,4-α-Glucan branching enzyme(GBE;EC 2.4.1.18),which plays an important role in starch modification,has been mostly expressed in Escherichia coli.The application of GBE in food industry is limited by the low yield of enzyme and production of endotoxins in E.coli.In this study,we first found that GBE from Geobacillus thermoglucosidans STB02(Gt-GBE)could be highly expressed in the Bacillus subtilis which is a food grade strain.The pathway of secretion was non-classical independent of signal peptides and was related to cell lysis.Bioinformatics analysis combined with site-directed mutagenesis was used to explore the influence of the N-terminal structure on its secretion.We found that the extracellular activity of Gt-GBE was increased about 17.29%and the secretion rate was also greatly improved through truncating the loop structure at the N-terminus.Besides,it was found that there was an optimal hydrophobicity,which increased the extracellular activity of Gt-GBE by 12.90%through the substitution of N-terminal amino acids with hydrophobic residues.In summary,we achieved high-efficiency non-classical secretion of Gt-GBE in B.subtilis and found an important role of the N-terminus in this secretion pathway,which provides a new perspective for improving the expression of proteins in B.subtilis.展开更多
n-3 polyunsaturated fatty acids(n-3 PUFA)have biologically important functions in human beings,but their contents in natural oils are usually low.This study investigated the concentration of n-3 PUFA-enriched glycerid...n-3 polyunsaturated fatty acids(n-3 PUFA)have biologically important functions in human beings,but their contents in natural oils are usually low.This study investigated the concentration of n-3 PUFA-enriched glycerides by Candida antarctica lipase A(CAL-A)-catalyzed selective methanolysis of algal oil.First,lipases and acyl acceptors were screened.Subsequently,the methanolysis conditions including methanol concentration in aqueous solution,molar ratio of methanol to oil,reaction temperature,lipase loading and reaction time,were optimized.The results indicated that CAL-A could effectively identify n-3 PUFA during methanolysis.Saturated fatty acids and monounsaturated fatty acids were released from algal oil by CAL-A-catalyzed methanolysis,causing the production of n-3 PUFA-enriched glycerides.Under optimal conditions(3:1 of molar ratio of methanol to algal oil,20%methanol aqueous solution,6%CAL-A dosage,25℃,18 h),the n-3 PUFA content increased from the initial 45.96%to 73.96%,with an n-3 PUFA yield of 81.76%.The reusability of CAL-A demonstrated that under optimal conditions the lipase could be used for 8 times.Therefore,this enzymatic process is efficient for synthesis of n-3 PUFA-enriched glycerides.展开更多
Enzymes have high activity at low temperatures are defined as cold-adapted enzymes,but few enzymes show an activation effect after low-temperature incubation.In this study,we cloned an agarase from the marine bacte-ri...Enzymes have high activity at low temperatures are defined as cold-adapted enzymes,but few enzymes show an activation effect after low-temperature incubation.In this study,we cloned an agarase from the marine bacte-rium Catenovulum agarivorans STB13(Ca-AGA)and expressed the protein in Bacillus subtilis.The enzyme exhibited a peculiar cold activation,which was enhanced by 5-fold after incubation at-20℃ or 4℃ for 6 h.Fluorescence and CD spectra studies confirmed the secondary and tertiary structural changes in Ca-AGA at low temperature,which formed compact protein structures after low-temperature treatment.The enzyme also showed outstanding cold adaptation,retaining approximately 60%of its maximum activity at 10℃.Based on a bioinformatics analysis,the carbohydrate-binding modules(CBMs)and long linker region were presumed to play a crucial role in cold adaptation due to a relatively high percentage of acidic residues and a negative charge density compared to the catalytic domain.A mutation that truncated the linker-CBM region resulted in a 59.97%reduction of the activity at 10℃.This study describes anα-agarase of cold activation and adaptation in detail,which may have great potential for producing functional agaro-oligosaccharides in food and pharmaceutical industrial applications at ambient temperature.展开更多
Maltotetraose(G4)consists of four glucose units linked by anα-1,4-glycosidic bond.This compound demonstrates remarkable versatility in food processing and exhibits specific physiological functions,suggesting promisin...Maltotetraose(G4)consists of four glucose units linked by anα-1,4-glycosidic bond.This compound demonstrates remarkable versatility in food processing and exhibits specific physiological functions,suggesting promising applications in the medical,chemical,and food sectors.However,due to the closely related physical and chemical properties of maltotriose(G3),G4,and maltopentose(G5),achieving high-purity G4 has been challenging,resulting in a staggering price of US$438.88 per gram.In this study,a novel and efficient bio-physical method was developed to produce high-purity G4.Initially,multi-enzymatic hydrolysis yielded G4 at a 65.83%purity.Subsequent processes involving yeast fermentation and SMB separation further enhanced the purity to an impressive 93.15%.Notably,this pioneering method represents the successful separation of G3,G4,and G5 to exclusively obtain high-purity G4 from maltooligosaccharides,surpassing previous purity achievements.Every facet of this bio-physical method underwent meticulous design and optimization,ensuring a production process that is environmentally friendly,safe,and efficient.To validate its practicality,pilot-scale production tests were conducted.The cost analysis indicates that producing high-purity G4 through this method amounts to only US$0.013 per gram,representing that the actual selling price of G4 was 33,760 times the production cost under this process.展开更多
基金financially supported by the National Key R&D Program of China(2022YFF1100600,2022YFF1100605)the Science and Technology Support Program(Modern Agriculture)of Jiangsu Province(BE2022323)the National Natural Science Foundation of China(32302011)。
文摘Resistant starch(RS)has attracted much researchers'attention because of its health-beneficial effects.Gut microbiota obviously shapes human health,but the effects of RS supplementation on the changes of human gut microbiota remain unclear.This observational meta-analysis aimed to reveal the effects of RS intake onα-diversity and composition of gut microbiota through meta-analysis.Two independent authors systematically searched articles from inception until February 2023 on four electronic databases.Twenty-four highly relevant trials were included conforming to Preferred Reporting Items for Systematic reviews and MetaAnalysis protocol,and a total of 816 individuals were included.Significant heterogeneity analyses revealed that RS intake notably decreased Shannon index(weighted mean difference(WMD):-0.11;95%confidence interval(CI):-0.21,-0.01),and stimulated the composition of health promoting bacteria genera,including Bifidobacterium(relative abundance:WMD:1.75;95%CI:0.39,3.11;bacterial populations:WMD:0.36;95%CI:0.04,0.69),Faecalibacterium(relative abundance:WMD:0.70;95%CI:0.20,1.20;fold change:effect size:0.91;95%CI:0.60,1.23),and Prevotella(relative abundance:WMD:0.35;95%CI:0.01,0.69).Taken together,the present study revealed that changes in the gut microbiota diversity and genera were correlated with RS supplementation,which may contribute to benefits in human health.
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This work was financially supported by National Key R&D Program of China(2021YFD2101001-2)the National Natural Science Foundation of China(No.31901628)+1 种基金the Fundamental Research Funds for the Central Universities(JUSRP121004)Science and Technology Support Program(Modern Agriculture)of Jiangsu Province(BE2022323).
文摘1,4-α-Glucan branching enzyme(GBE;EC 2.4.1.18),which plays an important role in starch modification,has been mostly expressed in Escherichia coli.The application of GBE in food industry is limited by the low yield of enzyme and production of endotoxins in E.coli.In this study,we first found that GBE from Geobacillus thermoglucosidans STB02(Gt-GBE)could be highly expressed in the Bacillus subtilis which is a food grade strain.The pathway of secretion was non-classical independent of signal peptides and was related to cell lysis.Bioinformatics analysis combined with site-directed mutagenesis was used to explore the influence of the N-terminal structure on its secretion.We found that the extracellular activity of Gt-GBE was increased about 17.29%and the secretion rate was also greatly improved through truncating the loop structure at the N-terminus.Besides,it was found that there was an optimal hydrophobicity,which increased the extracellular activity of Gt-GBE by 12.90%through the substitution of N-terminal amino acids with hydrophobic residues.In summary,we achieved high-efficiency non-classical secretion of Gt-GBE in B.subtilis and found an important role of the N-terminus in this secretion pathway,which provides a new perspective for improving the expression of proteins in B.subtilis.
基金This study was financially supported by"National Natural Science Foundation of China(Grant No.:31972035).
文摘n-3 polyunsaturated fatty acids(n-3 PUFA)have biologically important functions in human beings,but their contents in natural oils are usually low.This study investigated the concentration of n-3 PUFA-enriched glycerides by Candida antarctica lipase A(CAL-A)-catalyzed selective methanolysis of algal oil.First,lipases and acyl acceptors were screened.Subsequently,the methanolysis conditions including methanol concentration in aqueous solution,molar ratio of methanol to oil,reaction temperature,lipase loading and reaction time,were optimized.The results indicated that CAL-A could effectively identify n-3 PUFA during methanolysis.Saturated fatty acids and monounsaturated fatty acids were released from algal oil by CAL-A-catalyzed methanolysis,causing the production of n-3 PUFA-enriched glycerides.Under optimal conditions(3:1 of molar ratio of methanol to algal oil,20%methanol aqueous solution,6%CAL-A dosage,25℃,18 h),the n-3 PUFA content increased from the initial 45.96%to 73.96%,with an n-3 PUFA yield of 81.76%.The reusability of CAL-A demonstrated that under optimal conditions the lipase could be used for 8 times.Therefore,this enzymatic process is efficient for synthesis of n-3 PUFA-enriched glycerides.
基金financially supported by the National Key R&D Pro-gram of China(2019YFD0901901)the National Natural Science Foundation of China(No.32272263)Science and Technology Support Program(Modern Agriculture)of Jiangsu Province(BE2022323).
文摘Enzymes have high activity at low temperatures are defined as cold-adapted enzymes,but few enzymes show an activation effect after low-temperature incubation.In this study,we cloned an agarase from the marine bacte-rium Catenovulum agarivorans STB13(Ca-AGA)and expressed the protein in Bacillus subtilis.The enzyme exhibited a peculiar cold activation,which was enhanced by 5-fold after incubation at-20℃ or 4℃ for 6 h.Fluorescence and CD spectra studies confirmed the secondary and tertiary structural changes in Ca-AGA at low temperature,which formed compact protein structures after low-temperature treatment.The enzyme also showed outstanding cold adaptation,retaining approximately 60%of its maximum activity at 10℃.Based on a bioinformatics analysis,the carbohydrate-binding modules(CBMs)and long linker region were presumed to play a crucial role in cold adaptation due to a relatively high percentage of acidic residues and a negative charge density compared to the catalytic domain.A mutation that truncated the linker-CBM region resulted in a 59.97%reduction of the activity at 10℃.This study describes anα-agarase of cold activation and adaptation in detail,which may have great potential for producing functional agaro-oligosaccharides in food and pharmaceutical industrial applications at ambient temperature.
文摘Maltotetraose(G4)consists of four glucose units linked by anα-1,4-glycosidic bond.This compound demonstrates remarkable versatility in food processing and exhibits specific physiological functions,suggesting promising applications in the medical,chemical,and food sectors.However,due to the closely related physical and chemical properties of maltotriose(G3),G4,and maltopentose(G5),achieving high-purity G4 has been challenging,resulting in a staggering price of US$438.88 per gram.In this study,a novel and efficient bio-physical method was developed to produce high-purity G4.Initially,multi-enzymatic hydrolysis yielded G4 at a 65.83%purity.Subsequent processes involving yeast fermentation and SMB separation further enhanced the purity to an impressive 93.15%.Notably,this pioneering method represents the successful separation of G3,G4,and G5 to exclusively obtain high-purity G4 from maltooligosaccharides,surpassing previous purity achievements.Every facet of this bio-physical method underwent meticulous design and optimization,ensuring a production process that is environmentally friendly,safe,and efficient.To validate its practicality,pilot-scale production tests were conducted.The cost analysis indicates that producing high-purity G4 through this method amounts to only US$0.013 per gram,representing that the actual selling price of G4 was 33,760 times the production cost under this process.
