Structural analysis and characterization of dextran produced by wild and mutant strains of Leuconostoc mesenteroides

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• 作者：Nadir Naveed Siddiqui ; Afsheen Aman ; Alba Silipo ; Shah Ali Ul Qader ; Antonio Molinaro
• 关键词：EPS ; exopolysaccharide ; FTIR ; Fourier-transform infrared ; SEM ; scanning electron microscopy ; KIBGE-IB22 ; wild type ; KIBGE-IB22M20 ; mutant ; 1H NMR ; proton nuclear magnetic resonance spectroscopy ; 13C NMR ; carbon nuclear magnetic resonance spectroscopy ; 2D NMR ; two-dimensional nuclear magnetic resonance spectroscopy ; COSY ; homonuclear correlation spectroscopy ; DQF-COSY ; double quantum-filtered phase-sensitive COSY ; TOCSY ; total correlation spectroscopy ; HSQC ; heteronuclear single-quantum correlati
• 刊名：Carbohydrate Polymers
• 出版年：2 January, 2014
• 年：2014
• 卷：99
• 期：Complete
• 页码：331-338
• 全文大小：2243 K

文摘

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, ¹H NMR, ¹³C 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 伪-(1 鈫?#xA0;6) configuration with a small proportion of 伪-(1 鈫?#xA0;3) branching and the other was levan containing 尾-(2 鈫?#xA0;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.