The nutrition composition and bait effect of Prochlorococcus marinus

The microalgae Prochlorococcus marinus has a high reproductive rate and is abundantly distributed in the natural environment. To investigate the potential commercial values of Prochlorococcus, here we analyzed its nutritional composition using biochemical assay, and evaluated its feeding efficacy for Moina mongolica and Brachionus plicatilis using one-way ANOVA. Our results showed that Prochlorococcus consisted of crude proteins (42.32% of the total dry weight), crude lipids (11.47%), carbonhydrate (15.11%) and ash content (17.48%). The crude proteins were composed of 18 types of amino acids that accounted for 35.88% of the dry weight. Eight types were essential amino acids (37.54%). Thirteen types of fatty acids were also identified in the crude lipids, including 8 types of unsaturated fatty acids (58.26%). The crude lipids were enriched with monounsaturated fatty acids (54.12%) and were low in polyunsaturated fatty acids (4.14%). When fed with Prochlorococcus at the optimal density of 400104 cells/mL, M. mongolica displayed the highest net reproductive rate of 4.33 and the intrinsic growth rate of 0.23, and the concentration of accumulated EPA in M. mongolica reached 6.69%. The feeding density of Prochlorococcus also showed significant impact on the egg production and the egg mass rate of B. plicatilis. The optimal density was 600104 cells/mL during 48-96h and 400104 cells/mL during 96-144h. In conclusion, Prochlorococcus may have high nutritional values and thus could be effective feeding bait. We suggest that it should be mixed with other microalgae when used as feed for M. mongolica and B. plicatilis.