Effects of alginate oligosaccharides on the growth of various mammalian cell lines, phytoplankters, and marine bacteria were investigated. The growth of diatom, Chaetoceros gracilis, which is very useful phytoplankton in aquaculture industry, was promoted by alginate oligosaccharides in a concentration-dependent manner, whereas no significant effect of alginate oligosaccharides on the growth of various mammalian cell lines and two strains of marine bacterium, Edwardsiella tarda was observed. The maximum effect was attained at 125μg/ml of alginate oligosaccharides at which the maximum cell density of C. gracilis became nearly 140% higher than that of control without alginate oligosaccharides. However, the growth of another diatom, Skeletonema sp. was inhibited by alginate oligosaccharides in a concentration-depend manner. These results suggest that the growth promoting effect of alginate oligosaccharides is species-specific, and alginate oligosaccharides are useful for promoting and/or improving the growth of C. gracilis.
