环境因子对微藻胞外多聚物主要组分的影响

The Effect of Environmental Factors on the Principal Conponents of Microalgal Extracellular Polymeric Substances

胞外多聚物(extracellular polymeric substances,EPS)对于微藻细胞的生长和用途具有重要的影响.以1株葡萄藻、1株栅藻和2株小球藻为研究对象,考察氮源含量改变时微藻EPS中主要组分多糖和蛋白质的变化情况.选取长势最优的葡萄藻,研究pH值、温度和培养方式对EPS组分的影响.结果表明:缺氮的生长环境会引起EPS中蛋白质含量的减少,最多可减少56.0%;微藻EPS中最多的是胞外多糖,占总EPS组分的58.08%~80.78%,而胞外蛋白质含量则占5.73%~13.45%;相比葡萄藻和栅藻,小球藻胞外存在更多的多糖和蛋白质.对于葡萄藻,pH值为11时EPS中多糖和蛋白质含量(按每克细胞计)与pH值为7时相比分别增加0.135和0.018g;降低温度使EPS多糖含量从0.014g急剧增加到0.600g;异养培养时EPS中多糖含量更高而自养培养时蛋白质含量更高.

Extracellular polymeric substances （EPS） have an important effect on cell growth, flocculation, biofilm formation, etc. ln this paper,one strain of Botryococcus,one strain of Sceneclesrnus,and two strains of ChloreHa were selected to investigate the poly saccharide and protein in EPS when the nitrogen content, pH, temperature and the culture mode changed.The results showed that the nitrogen deficient growth environment caused a reduction of up to 56.0%in protein. Polysaccharides accounted for 58.08% to 80.78% of EPS,while proteins accounted for 5.73% to 13. dSY0.fhere were more polysaccharides and proteins in Chlorella strains than in other species.As elaborated in the representative Botryococcus strain, when the pH value was 11 ,the polysaccharide and pro rein contents （per gram of cell weight） in EPS approximately increased by 0. 135 g and 0. 018 g,respectively,compared with the data at pH 7.The content of polysaccharide also increased from 0.01d g to 0. 600 g as the temperature decreased.When the culture mode changed, the polysaccharide content in EPS of the heterotrophic cultivation was higher than that of the autotrophic cultivation, while the protein content showed the opposite trend.