Effects of different culture conditions on growth and astaxanthin and lipid accumulation in Oedocladium sp.

The effects of two-step culture on growth and lipid and astaxanthin accumulation in Oedocladium sp. (filamentous green algae) were studied under three light intensities (100, 300, and bilateral 300 μmol·m^-2·s^-1) and four nitrogen concentrations (1, 3, 9, and 18 mmol/L). After 12 d of incubation, the media in the experimental groups were replaced with nitrogen-free and/or salt-added medium (50 mmol/L), with the control group medium not replaced. Under bilateral 300 μmol·m^-2·s^-1 light intensity, maximum biomass (9.61 g/L) was obtained when the medium with an initial nitrogen concentration of 18 mmol/L was replaced by medium without nitrogen. The highest astaxanthin and lipid content reached 1.62% and 51.19% of dry weight, respectively, which was attained under an initial nitrogen concentration of 3 mmol/L, salt-added culture medium replacement, and bilateral 300 μmol·m^-2·s^-1 light intensity. In short, high light intensity was beneficial for Oedocladium sp. growth. The optimum conditions for astaxanthin and lipid accumulation were low nitrogen concentration with salt (50 mmol/L) medium under bilateral 300 μmol·m^-2·s^-1 light intensity.