Growth-promoting effect of alginate oligosaccharides on a unicellular marine microalga, Nannochloropsis oculata.

Effects of an alginate oligosaccharide mixture (AOM) on Nannochloropsis oculata, a unicellular marine microalga, were investigated. The growth of N. oculata was significantly promoted by AOM in a concentration-dependent manner. The maximum effect was attained at 20 mg/ml, at which the growth rate of the alga became nearly 5 times higher than that of control without AOM. The growth-promoting effect of AOM decreased slightly at 40 mg/ml. Furthermore, the algicidal effect of Cu(2+) was profoundly alleviated by the addition of AOM. These results suggest that AOM is useful for promoting and/or improving the growth of N. oculata.