title: Structural analysis and characterization of dextran produced by wild and mutant strains of Leuconostoc mesenteroides.
abstract: An exopolysaccharide known as dextran was produced by Leuconostoc mesenteroides KIBGE-IB22 (wild) and L. mesenteroides KIBGE-IB22M20 (mutant). The structure was characterized using FTIR, (1)H NMR, (13)C NMR and 2D NMR spectroscopic techniques, whereas surface morphology was analyzed using SEM. A clear difference in the spectral chemical shift patterns was observed in both samples. All the spectral data indicated that the exopolysaccharide produced by KIBGE-IB22 is a mixture of two biopolymers. One was dextran in α-(1 → 6) configuration with a small proportion of α-(1 → 3) branching and the other was levan containing β-(2 → 6) fructan fructofuranosyl linkages. However, remarkably the mutant only produced dextran without any concomitant production of levan. Study suggested that the property of KIBGE-IB22M20, regarding improved production of high molecular weight dextran in a shorter period of fermentation time without any contamination of other exopolysaccharide, could be employed to make the downstream process more feasible and cost effective on large scale.
authors.affiliation: The Karachi Institute of Biotechnology & Genetic Engineering (KIBGE), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Nadir Naveed
authors.initials: NN
authors.lastname: Siddiqui
authors.forename: Afsheen
authors.initials: A
authors.lastname: Aman
authors.forename: Alba
authors.initials: A
authors.lastname: Silipo
authors.forename: Shah Ali Ul
authors.initials: SA
authors.lastname: Qader
authors.forename: Antonio
authors.initials: A
authors.lastname: Molinaro
mesh_terms: D003911:Dextrans / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D005285:Fermentation; D005630:Fructans / Q000737:chemistry; D007934:Leuconostoc / Q000235:genetics / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D009154:Mutation; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003911:Dextrans; D005630:Fructans; C072599:levan
keywords: (1)H NMR; (13)C NMR; 2D NMR; COSY; DQF-COSY; Dextran; EPS; Exopolysaccharide; FTIR; Fourier-transform infrared; HMBC; HSQC; KIBGE-IB22; KIBGE-IB22M20; Leuconostoc mesenteroides; Levan; Mutation; NOESY; ROESY; SEM; TOCSY; carbon nuclear magnetic resonance spectroscopy; double quantum-filtered phase-sensitive COSY; exopolysaccharide; heteronuclear multiple-bond correlation spectroscopy; heteronuclear single-quantum correlation spectroscopy; homonuclear correlation spectroscopy; mutant; nuclear Overhauser effect spectroscopy; proton nuclear magnetic resonance spectroscopy; rotating frame nuclear Overhauser effect spectroscopy; scanning electron microscopy; total correlation spectroscopy; two-dimensional nuclear magnetic resonance spectroscopy; wild type