Hokkaido University Research Profiles


Structural Analysis of Polysaccharides and Proteins That Cause Membrane Fouling

Although membrane treatment is attracting attention as a next-generation water treatment technology, the degradation of membrane permeability (membrane fouling) has been a barrier to its widespread use. In this study, we conducted the world’s first structural analysis of polysaccharides and proteins, which are the main causes of membrane fouling, for the rational control of membrane fouling.

Content of research

Membrane fouling (decrease in membrane permeability) is mainly caused by polysaccharides and proteins produced by microorganisms. However, it is still unclear which polysaccharides and proteins play an important role in that mechanism, and efficient methods to control membrane fouling has yet to be developed. In this study, we accumulated fouling polysaccharides, purified them by lectin affinity chromatography, and then conducted partial hydrolysis and MALDI-TOF/MS analysis. By comparing the peaks detected by MALDI-TOF/MS analysis with the database, we have enabled estimation of the structure of the polysaccharide and the microorganism from which it originated. We have also succeeded in separating proteins by two-dimensional electrophoresis after purifying the membrane fouling material, enabling the reading of the amino acid sequences of the cut-out spots. It is also possible to estimate the structure and origin of the protein by comparing it with the database.

  • MALDI-TOF/MS spectra of polysaccharides causing membrane fouling

  • An example of polysaccharide structure inferred from MALDI-TOF/MS spectra

  • 2D-PAGE swimming diagram of membrane fouling material

  • Amino acid sequence analysis results

Potential for social implementation

  • ・Development of a novel method of inhibiting membrane fouling through the selective detection and tracking of fouling polysaccharides, proteins, or the microorganisms that produce them
  • ・New development of fouling-resistant membranes using truly important polysaccharides and proteins

Appealing points to industry and local governments

Previous attempts to suppress membrane fouling have been irrational and ineffective due to the critical lack of information on the components that cause membrane fouling. If the components that cause membrane fouling can be identified for each application using the method developed in this study, it may lead to the development of an innovative membrane fouling suppression method that is completely different from previous methods.