Benigar Elizabeta, Dogsa Iztok, Stopar David, Jamnik Andrej, Kralj Cigić Irena, Tomšič Matija
Faculty of Chemistry and Chemical Technology, University of Ljubljana , Aškerčeva 5, SI-1000 Ljubljana, Slovenia.
Langmuir. 2014 Apr 15;30(14):4172-82. doi: 10.1021/la500830j. Epub 2014 Apr 4.
The polysaccharide levan is a homopolymer of fructose and appears in nature as an important structural component of some bacterial biofilms. This paper reports the structural and dynamic properties of aqueous solutions of levan of various origin obtained from dynamic rheological, small-angle X-ray scattering, static and dynamic light scattering, as well as density and sound velocity measurements, determination of polymer branching after per-O-methylation, and microscopy. Besides samples of commercially available levan from Zymomonas mobilis and Erwinia herbicola, we also isolated, purified, and studied a levan sample from the biofilm of Bacillus subtilis. The results of dynamic rheological and light scattering measurements revealed very interesting viscoelastic properties of levan solutions even at very low polymer concentrations. The findings were complemented by small-angle X-ray scattering data that revealed some important differences in the structure of the aqueous levan solutions at the molecular level. Besides presenting detailed dynamic and structural results on the polysaccharide systems of various levans, one of the essential goals of this work was to point out the level of structural information that may be obtained for such polymer systems by combining basic physicochemical, rheological, and various light scattering techniques.
多糖果聚糖是果糖的均聚物，在自然界中是一些细菌生物膜的重要结构成分。本文通过动态流变学、小角X射线散射、静态和动态光散射以及密度和声速测量、全O-甲基化后聚合物支化的测定和显微镜观察，报道了不同来源的果聚糖水溶液的结构和动态性质。除了来自运动发酵单胞菌和草生欧文氏菌的市售果聚糖样品外，我们还从枯草芽孢杆菌的生物膜中分离、纯化并研究了一个果聚糖样品。动态流变学和光散射测量结果表明，即使在极低的聚合物浓度下，果聚糖溶液也具有非常有趣的粘弹性。小角X射线散射数据补充了这些发现，揭示了果聚糖水溶液在分子水平上结构的一些重要差异。除了展示关于各种果聚糖的多糖体系的详细动态和结构结果外，这项工作的一个基本目标是指出通过结合基本的物理化学、流变学和各种光散射技术，可以为此类聚合物体系获得的结构信息水平。
