Purification and conformational analysis of a key exopolysaccharide component of mixed culture aerobic sludge granules.
Purification and conformational analysis of a key exopolysaccharide component of mixed culture aerobic sludge granules.
复制标题
DOI：
10.1021/es100362b
复制
发表时间：
2010-06
影响因子：
11.4
通讯作者：
T. Seviour;B. Donose;M. Pijuan;Zhiguo Yuan
中科院分区：
文献类型：
--
作者：
T. Seviour;B. Donose;M. Pijuan;Zhiguo Yuan
好氧污泥颗粒在废水处理中的应用可以增加废水处理过程的强度，因为它们相对于传统污泥絮体具有更大的密度和尺寸。有人提出，颗粒与絮凝物的区别在于形成凝胶的胞外多糖。在这项研究中，证据表明特定的胞外多糖成分与颗粒胞外聚合物 (EPS) 凝胶化有关。颗粒状 EPS 由三种成分组成：高分子量 (MW) 胞外多糖、中分子量蛋白质和糖苷、低分子量蛋白质和糖苷。通过分级沉淀和制备型凝胶渗透色谱 (GPC) 分离高分子量组分。该级分的分子量分布似乎完全归因于高分子量多糖。胞外多糖在正常废水处理操作 pH 值（即 6.0-8.5）下以凝胶形式存在，而低/中分子量材料则不然。对干燥材料进行原子力显微镜 (AFM) 构象分析表明，多糖溶解在 Milli-Q 水中时形成珍珠项链状的分子内缩合结构，而在碱溶液中则形成部分松弛的螺旋聚集体。因此，所测试的好氧污泥颗粒中 EPS 的凝胶形成特性可能与高分子量多糖成分有关。
The application of aerobic sludge granules in wastewater treatment could increase the intensity of wastewater treatment processes because of their greater density and size relative to conventional sludge flocs. It has been suggested that granules are distinguished from flocs by gel forming exopolysaccharides. In this study, evidence is presented linking a specific exopolysaccharide component with granule extracellular polymeric substance (EPS) gelation. Granular EPS comprised three components: high-molecular-weight (MW) exopolysaccharide, medium-MW proteins and glycosides, and low-MW proteins and glycosides. The high-MW fraction was separated by fractional precipitation and preparatory-scale gel permeation chromatography (GPC). The MW profile of this fraction appears to be exclusively attributable to high-MW polysaccharide. The exopolysaccharide exists as a gel at normal wastewater treatment operating pH (i.e., 6.0-8.5), whereas the low/medium-MW material does not. Conformational analysis by atomic force microscopy (AFM) of the dried material showed that the polysaccharide forms pearl-necklace-like, intramolecularly condensed structures when dissolved in Milli-Q water and partially relaxed helical aggregates when in alkali solution. Consequently, the gel-forming property of EPS in the aerobic sludge granules tested is probably associated with high-MW polysaccharide components.