Department of Desalination and Water Treatment, Zuckerberg Institute for Water Research, Albert Katz International School for Desert Studies, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev , Sede Boqer Campus 84990, Israel.
Environ Sci Technol. 2014 Dec 2;48(23):13941-50. doi: 10.1021/es503680s. Epub 2014 Nov 11.
In the present study, we investigate the possible contribution of Sphingomonas spp. glycosphingolipids (GSL) and its extracellular polymeric substances (EPS) to the initial colonization and development of biofilm bodies on reverse osmosis (RO) membranes. A combination of an RO cross-flow membrane lab unit, a quartz crystal microbalance with dissipation (QCM-D), and a rear stagnation point flow (RSPF) system with either model bacteria (Sphingomonas wittichii, Escherichia coli, and Pseudomonas aeruginosa) or vesicles made of the bacterial GSL or LPS was used. Results showed noticeable differences in the adhesion LPS versus GSL vesicles in the QCM-D, with the latter exhibiting 50% higher adhesion to polyamide coated crystals (mimicking an RO membrane surface). A similar trend was observed for EPS extracted from S. wittichii, when compared to the adhesion tendency of EPS extracted from P. aeruginosa. By applying the whole-cell approach in the RO lab unit, the cumulative impact of S. wittichii cells composing GSL and probably their EPS reduced the permeate flux during bacterial accumulation on the membrane surface. Experiments were conducted with the same amount of Sphingomonas spp. or Escherichia coli cells resulting in a two times greater flux decline in the presence of S. wittichii. The distinct effects of Sphingomonas spp. on RO membrane biofouling are likely a combination of GSL presence (known for enhancing adhesion when compared to non-GSL containing bacteria) and the EPS contributing to the overall strength of the biofilm matrix.
在本研究中，我们研究了鞘氨醇单胞菌属糖脂（GSL）及其细胞外聚合物（EPS）对反渗透（RO）膜上生物膜体初始定植和发育的可能贡献。采用 RO 错流膜实验室装置、石英晶体微天平（QCM-D）和后驻点流（RSPF）系统相结合的方法，利用模型细菌（鞘氨醇单胞菌、大肠杆菌和铜绿假单胞菌）或由细菌 GSL 或 LPS 制成的囊泡。结果表明，在 QCM-D 中，LPS 与 GSL 囊泡的粘附存在显著差异，后者对聚酰胺涂层晶体的粘附率高出 50%（模拟 RO 膜表面）。与铜绿假单胞菌 EPS 的粘附趋势相比，从鞘氨醇单胞菌中提取的 EPS 也表现出类似的趋势。通过在 RO 实验室装置中应用全细胞方法，构成 GSL 的鞘氨醇单胞菌细胞及其可能的 EPS 的累积影响降低了细菌在膜表面积累时的渗透通量。实验中使用了等量的鞘氨醇单胞菌或大肠杆菌细胞，结果表明，在存在鞘氨醇单胞菌的情况下，通量下降了两倍。鞘氨醇单胞菌对 RO 膜生物污染的明显影响可能是 GSL 存在的综合影响（与不含有 GSL 的细菌相比，GSL 增强了粘附性）和 EPS 对生物膜基质整体强度的贡献。
