Extracellular polymeric substances (EPS) play crucial roles in bio-aggregate formation and survival of bacterial cells. To develop an effective but harmless method for EPS extraction from Shewanella oneidensis MR-1, five extraction methods, i.e. centrifugation (control), heating (40, 45, 50, and 60 °C), and treatments with H2SO4, ethylenediaminetetraacetic acid (EDTA) and NaOH, were examined, respectively. Results from scanning electron microscope and flow cytometric analyses indicate that MR-1 cells were severely broken by H2SO4, NaOH and heating temperature ≥45 °C. Proteins and polysaccharides in EPS extracted by heating at 40 °C were 7.12 and 1.60 mg g−1 dry cell, respectively. Although EDTA treatment had a relatively lower yield of EPS (proteins and polysaccharides yields of 5.15 and 1.30 mg g−1 dry cell, respectively), cell lysis was barely found after EPS extraction. Three peaks were identified from the three-dimensional excitation–emission matrix spectrum of each EPS sample, suggesting the presence of protein-like substances. Furthermore, the peak intensity was in good accordance with protein concentration measured by the chemical analysis. In short, heating (40 °C) and EDTA treatments were found the most suitable methods for EPS extraction considering the cell lysis and EPS content, composition and functional groups together.
Effective methods for extracting extracellular polymeric substances from Shewanella oneidensis MR-1
You-Fen Dai, Yong Xiao, En-Hua Zhang, Li-Dan Liu, Ling Qiu, Le-Xing You, Gurumurthy Dummi Mahadevan, Bi-Lian Chen, Feng Zhao; Effective methods for extracting extracellular polymeric substances from Shewanella oneidensis MR-1. Water Sci Technol 20 December 2016; 74 (12): 2987–2996. doi: https://doi.org/10.2166/wst.2016.473
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