Studies on the chemical compositions of extracellular polymeric substances from marine benthic diatoms

The marine benthic diatoms slide and attach on the surface by extracellular polymeric substance (EPS). To investigate the difference of EPS at different growth cycle and recognize the variety of EPS from different species of diatoms, we measured and quantified the EPS from single cell. The water-soluble and water-insoluble components in EPS from marine benthic diatoms were extracted by hot solvent method. The phenol-sulfuric acid method was employed to measure the content of polysaccharide and the Coomassie Brilliant Blue G-250 method was employed to measure the content of protein in the extractions. The results showed that the contents of polysaccharide and protein in EPS were reduced with the increase of cell density for Navicula pinna at different growth cycle, and the contents of polysaccharide and protein had differences, indicating that the growth cycle of diatom had influenced for secretion action of EPS. The contents of EPS from diatoms (Navicula leavissima, Navicula parva, and Navicula pinna) were different at the exponential stage, but the percentage of polysaccharide and protein in EPS had no differences.