Specific growth rate, colonial morphology and extracellular polysaccharides (EPS) content of Scenedesmus obliquus grown under different levels of light limitation

Abstract

In order to investigate the role of extracellular polysaccharide (EPS) in colony formation of Scenedesmus obliquus, the relationships among morphological characteristics, EPS content and specific growth rate of S. obliquus are investigated in this study. S. obliquus cultured under varying light intensities exhibited different specific growth rates, when the specific growth rate decreased from 0.65 to 0.40 day-1 the cells per particle of S. obliquus increased from 1.2 to 2.8; but the cells per particle fell back to 1.2 as the specific growth rate further decreased from 0.40 to 0.14 day-1. Moreover, a negative relationship between the specific growth rate and EPS content was found when the specific growth rate was lower than 0.4 day-1; however, the EPS content maintained at a relatively steady state (0.14-0.20 pg cell-1) when the specific growth rate was higher than 0.4 day-1. No significant relationship was identified between EPS content and cells per particle of S. obliquus. This result revealed that the increasing EPS content may not lead to colony formation of S. obliquus, which can provide a deeper insight into the role of EPS content in colony formation of different algae.