title: Synthesis of raffinose by transfructosylation using recombinant levansucrase from Clostridium arbusti SL206.
abstract: BACKGROUND
  Raffinose, a functional trisaccharide of α-d-galactopyranosyl-(1 → 6)-α-d-glucopyranosyl-(1 → 2)-β-d-fructofuranoside, is a prebiotic that shows promise for use as a food ingredient.
  
  
  RESULTS
  In this study, the production of raffinose from melibiose and sucrose was studied using whole recombinant Escherichia coli cells harboring the levansucrase from Clostridium arbusti SL206. The reaction conditions were optimized for raffinose synthesis. The optimal pH, temperature and washed cell concentration were pH 6.5 (sodium phosphate buffer, 50 mmol L-1), 55 °C and 3% (w/v), respectively. High substrate concentrations, which led to low water activity and thus reduced levansucrase hydrolysis activity, strongly favored the production of raffinose through the fructosyl transfer reaction. Additionally, high concentrations of excess acceptor and donor glycosides favored raffinose production. When 30% (w/v) sucrose and 30% (w/v) melibiose were catalyzed using 3% (w/v) whole cells at pH 6.5 (sodium phosphate buffer, 50 mmol L-1) and 55 °C, the highest raffinose yield was 222 g L-1after a 6 h reaction. The conversion ratio from each substrate to raffinose was 50%.
  
  
  CONCLUSIONS
  Raffinose could be effectively produced with melibiose as an acceptor and with sucrose as a fructosyl donor by whole recombinant E. coli cells harboring C. arbusti levansucrase. The yield from E. coli was significantly higher than those of the previously reported Bacillus subtilis levansucrase and fungal α-galactosidases. © 2016 Society of Chemical Industry.
authors.affiliation: State Key Laboratory of Food Science and Technology, Ministry of Education, Key Laboratory of Carbohydrate Chemistry and Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, Ministry of Education, Key Laboratory of Carbohydrate Chemistry and Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors.forename: Shuhuai
authors.initials: S
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Food Science and Technology, Ministry of Education, Key Laboratory of Carbohydrate Chemistry and Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Ministry of Education, Key Laboratory of Carbohydrate Chemistry and Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Food Science and Technology, Ministry of Education, Key Laboratory of Carbohydrate Chemistry and Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China.
authors.forename: Wanmeng
authors.initials: W
authors.lastname: Mu
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003013:Clostridium / Q000201:enzymology*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005632:Fructose / Q000378:metabolism; D006602:Hexosyltransferases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008553:Melibiose / Q000378:metabolism; D011887:Raffinose / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D005632:Fructose; D013395:Sucrose; D008553:Melibiose; D006602:Hexosyltransferases; C021513:levansucrase; D011887:Raffinose
keywords: Clostridium arbusti SL206; levansucrase; raffinose; synthesis; transfructosylation