Abstract: β-Glucan is considered as a potential functional polysaccharide. The adaptive laboratory evolution was used to induce Agrobacterium sp. to produce low molecular weight β-glucan with glycerol, and the antioxidant activity was determined. Agrobacterium sp.WS-8E3T produced, a novel polysaccharide, β-gluco-oligosaccharides (BGOs) with 2 800-3 600 Da stably after 120 h in 100 g/L glycerol shake flask. The BGOs was analyzed by infrared spectrum, monosaccharide composition and NMR, which proved that BGOs was β-1,3-glucan. The BGOs had antioxidant capacity with the scavenging rate of DPPH radical and hydroxyl radical reached to 80% of ascorbic acid. The results showed that the BGOs had better antioxidant properties, and provides the basis for the application of BGOs in the functional food and medicine field.
 SUN N X,TONG L T,LIANG T T,et al.Effect of oat and Tartary buckwheat-based food on cholesterol-lowering and gut microbiota in hypercholesterolemic hamsters[J].Journal of Oleo Science,2019,68(3):251-259.  KHAN A A,GANI A,SHAH A,et al.Effect of γ-irradiation on structural,functional and antioxidant properties of β-glucan extracted from button mushroom (Agaricus bisporus)[J].Innovative Food Science and Emerging Technologies,2015,31:123-30.  WANG H,WEENING D,JONKERS E,et al.A curve fitting approach to estimate the extent of fermentation of indigestible carbohydrates[J].European Journal of Clinical Investigation,2008,38(11):863-868.  SHI Y,LIU J,YAN Q,et al.In vitro digestibility and prebiotic potential of curdlan (1→3)-beta-D-glucan oligosaccharides in Lactobacillus species[J].Carbohydrate Polymers,2018,188:17-26.  JEDDOU K B,BOUAZIZ F,HELBERT C B,et al.Structural,functional,and biological properties of potato peel oligosaccharides[J].International Journal of Biological Macromolecules,2018,112(11):46-55.  MCINTOSH M,STONE B A,STANISICH V A.Curdlan and other bacterial (1→3)-β-D-glucans[J].Applied Microbiology & biotechnology,2005,68(2):163-173.  陆光兴.热凝胶葡寡糖的高效定向水解制备及其生物活性研究[D].无锡:江南大学,2015. LU G X,Efficient preparation of linear β-1,3-glucooligosaccharides by directed hydrolysis of Curdlan and characterization of its biological activity[D].Wuxi:JiangNan University,2015.  AMINI S R,HOSSEINI H,BONDARIANZADEH D,et al.Optimization of prebiotic sausage formulation:Effect of using β-glucan and resistant starch by D-optimal mixture design approach[J].LWT-Food Science and Technology,2015,62(1):704-710.  TURUNEN K T,PLETSA V,GEORGIADIS P,et al.Impact of beta-glucan on the fecal water genotoxicity of polypectomized patients[J].Nutrition and Cancer-An International Journal,2016,68(4):560-567.  VEVERKA M,DUBAJ T,VEVERKOVá E,et al.Natural oil emulsions stabilized by β-glucan gel[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2018,537(3):90-98.  YANG Z S,SUN A P,ZHAO X S,et al.Preparation and application of a beta-D-glucan microsphere conjugated protein A/G[J].International Journal of Biological Macromolecules,2020,151:878-884.  ZHU Q,WU S.Water-soluble beta-1,3-glucan prepared by degradation of curdlan with hydrogen peroxide[J].Food Chemistry,2019,283(30):2-4.  宗玉, 李晶,朱莉,等.两步法硫酸水解热凝胶生产β-1,3-葡寡糖[J].工业微生物,2014,44(1):22-27. ZONG Y,LI J,ZHU L,et al.Preparation of β-1,3-glucan oligosaccharides by two-step sulfuric acid hydrolysis of curdlan[J].Industrial Microbiology,2014,44(1):22-27.  GRANDPIERRE C,JANSSEN H G,LAROCHE C,et al.Enzymatic and chemical degradation of curdlan targeting the production of β-(1→3) oligoglucans[J].Carbohydrate Polymers,2008,71(2):277-286.  OKOYE P U,HAMEED B H.Review on recent progress in catalytic carboxylation and acetylation of glycerol as a byproduct of biodiesel production[J].Renewable and Sustainable Energy Reviews,2016,53(5):58-74.  王如月, 余讯,徐静静,等.燕麦β-葡聚糖及其寡糖对肠道菌群结构和代谢的影响[J].食品与发酵工业,2020,46(11):85-91. WANG R Y,YU X,XU J J,et al.Effects of oat β-glucan and its oligosaccharides on composition and metabolism of intestinal microorganisms[J].Food and Fermentation Industries,2020,46(11):85-91.  LIU Y,GU Q,OFOSU F K,et al.Production,structural characterization and gel forming property of a new exopolysaccharide produced by Agrobacterium HX1126 using glycerol or d-mannitol as substrate[J].Carbohydrate Polymers,2016,136(9):17-22.  KUAN Y H,NAFCHI A M,HUDA N,et al.Effects of sugars on the gelation kinetics and texture of duck feet gelatin[J].Food Hydrocolloids,2016,58(2):67-75.  韦铮, 贺燕,郝麒麟,等.茶多糖在模拟胃肠消化体系的抗氧化作用[J].食品与发酵工业,2020,46(10):109-117. WEI Z,HE Y,HAO Q L,et al.Study on the antioxidant effect of tea polysaccharides under the conditions of simulating gastrointestinal digestion in vitro [J].Food and Fermentation Industries,2020,46(10):109-117.  LEI N,WANG M,ZHANG L,et al.Effects of low molecular weight yeast beta-glucan on antioxidant and immunological activities in mice[J].International Journal of Molecular Science,2015,16(9):21 575-21 590.  DE AVELLAR I G J,MAGALH?ES M M M,SILVA A B,et al.Reevaluating the role of 1,10-phenanthroline in oxidative reactions involving ferrous ions and DNA damage[J].Biochimica et Biophysica Acta,2004,1675(1-3):46-53.  CHEUNG Y C,YIN J Y,WU J Y.Effect of polysaccharide chain conformation on ultrasonic degradation of curdlan in alkaline solution[J].Carbohydrate Polymers,2018,195:298-302. [23 RUFFING A M,CASTRO-MELCHOR M,HU W S,et al.Genome sequence of the curdlan-producing Agrobacterium sp.strain ATCC 31749[J].Journal of Bacteriology,2011,193(16):4 294-4 295.  PORTERFIELD J Z,ZLOTNICK A.A simple and general method for determining the protein and nucleic acid content of viruses by UV absorbance[J].Virology,2010,407(2):281-288.  HE P F,HE L,ZHANG A Q,et al.Structure and chain conformation of a neutral polysaccharide from Sclerotia of Polyporus umbellatus[J].Carbohydrate Polymers,2017,155:61-67.  BOSE S K,HOWLADER P,WANG W X,et al.Oligosaccharide is a promising natural preservative for improving postharvest preservation of fruit:A review[J].Food Chemistry,2021,341(Pt 1):128 178.  CHEN Z Y,ZHAO Y,ZHANG M K,et al.Structural characterization and antioxidant activity of a new polysaccharide from Bletilla striata fibrous roots[J].Carbohydrate Polymers,2020,227:115 362.  许女, 贾瑞娟,陈旭峰,等.鸡腿菇子实体多糖的体内、体外抗氧化活性[J].中国食品学报,2019,19(1):34-40. XU N,JIA R J,CHEN X F,et al.Antioxidant activity in vitro and vivo of polysaccharide from Coprinus comatus[J].Journal of Chinese Institute of Food Science and Technology,2019,19(1):34-40.