Molar mass, entanglement, and associations of the biofilm polysaccharide of Staphylococcus epidermidis.
Molar mass, entanglement, and associations of the biofilm polysaccharide of Staphylococcus epidermidis.
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DOI：
10.1021/bm400149a
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发表时间：
2013-05-13
影响因子：
6.2
通讯作者：
Solomon, Michael J.
中科院分区：
文献类型：
--
作者：
Ganesan, Mahesh;Stewart, Elizabeth J.;Szafranski, Jacob;Satorius, Ashley E.;Younger, John G.;Solomon, Michael J.
生物膜是以粘弹性胞外聚合物(EPS)的存在为特征的微生物群落。研究表明，多糖以及蛋白质和DNA是EPS的主要成分，在调节EPS的微观结构和流变性方面起着主导作用。在这里，我们研究了从表皮葡萄球菌生物膜中提取的胞外多糖胞间粘附素(PIA)溶液中存在缠结和缔合复合体的可能性。我们报道了PIA分离株的重均摩尔质量和旋转半径分别为2.01×105±1200g/mol和29.2±1.2 nm。由此确定线圈重叠浓度c*为(32±4)×10−4g/m L。测得生物膜的原位浓度为(10±2)×10−4g/m L。因此，CPIA、Biofilm<；c*和生物膜中的PIA含量太低，不会导致聚合物链缠绕。在pH为3.0~5.5的范围内，PIA与牛血清白蛋白(BSA)形成络合物，并与其形成络合物。通过静态光散射实验发现，当PIA浓度为0.30×10−4g/mL或更大时，自缔合和与0.5%(w/v)牛血清白蛋白形成络合物，比测得的CPIA生物膜低约30倍。这些结果表明，EPS粘弹性的微观起源不太可能是由于多糖的缠结。此外，PIA的自结合和蛋白质络合的起始浓度远远低于生物膜中天然的PIA浓度。因此，这一发现表明，这两种联合机制在调节生物膜粘弹性方面发挥了关键作用。
Biofilms are microbial communities that are characterized by the presence of a viscoelastic extracellular polymeric substance (EPS). Studies have shown that polysaccharides, along with proteins and DNA, are a major constituent of the EPS, and play a dominant role in mediating its microstructure and rheological properties. Here, we investigate the possibility of entanglements and associative complexes in solutions of extracellular polysaccharide intercellular adhesin (PIA) extracted from Staphylococcus epidermidis biofilms. We report that the weight average molar mass and radius of gyration of PIA isolates are 2.01 × 105 ± 1200 g/mol and 29.2 ± 1.2 nm respectively. The coil overlap concentration, c*, was thus determined to be (32 ± 4) × 10−4 g/mL. Measurements of the in situ concentration of PIA (cPIA,Biofilm) was found to be (10 ± 2) × 10−4 g/mL. Thus, cPIA,Biofilm < c* and the amount of PIA in the biofilm is too low to cause polymer chain entanglements. In the pH range 3.0 to 5.5, PIA was found to both self-associate and to form complexes with bovine serum albumin (BSA). By static light scattering, both self-association and complex formation with 0.5 %(w/v) BSA were found to occur at PIA concentrations of 0.30 × 10−4 g/mL and greater, which is about 30 times lower than the measured cPIA,Biofilm. These results suggest that the microscopic origin of EPS viscoelasticity is unlikely to be due to polysaccharide entanglements. Furthermore, the onset of self-association and protein complexation of PIA occurs at concentrations far lower than the native PIA concentration in biofilms. This finding therefore suggests a critical role for those two association mechanisms in mediating biofilm viscoelasticity.
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影响因子：
6.2
作者：
Braccini, I;Pérez, S
通讯作者：
Pérez, S
影响因子：
3.1
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Joyce, JG;Abeygunawardana, C;Mark, GE
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2.2
作者：
Körstgens, V;Flemming, HC;Borchard, W
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Borchard, W
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3.2
作者：
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通讯作者：
Mack, D
影响因子：
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作者：
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通讯作者：
Flemming, Hans-Curt