海洋底栖硅藻胞外多聚物化学成分的定量研究

海洋底栖硅藻通过分泌胞外多聚物（Extracellular polymeric substance，EPS）实现滑行运动和附着。为探查不同生长期硅藻EPS的变化，以及同一生长期不同硅藻EPS的异同，本文以单个细胞分泌的EPS为考量依据，进行了定量分析。采用热溶剂浸提法对海洋底栖硅藻EPS的水溶性和水不溶性组分进行提取；利用苯酚-硫酸法定量提取液中的多糖，利用考马斯亮蓝G-250法定量蛋白质。结果表明，不同生长期的羽状舟形藻（Navicula pinna），随着细胞密度增大，EPS中多糖和蛋白质的分泌量减少，且多糖和蛋白质含量存在差异，表明EPS分泌行为因硅藻生长期不同而发生变化；同为生长指数期，三种海洋底栖硅藻:平滑舟形藻（Navicula leavissima）、小形舟形藻（Navicula parva）、羽状舟形藻（Navicula pinna）的EPS分泌量不同，但EPS中的多糖和蛋白质百分含量无明显差别。

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.