Ferulic acid extracted from rice bran as a growth promoter for the microalga Nannochloropsis oculata

In microalga culturing, one important topic is finding methods of increasing the productivity of algal biomass grown on a large scale. The cultured microalgal biomass must be inexpensive to produce, but rich in the bioactive substances, for use as raw materials for many different purposes, such as functional foods, drugs, pharmaceuticals, cosmetics, and biofuels. Here we present results about the effects of ferulic acid extracted from rice bran on the growth, photosynthetic activity, and valuable substance content of the eustigmatophyte Nannochloropsis oculata. The results showed that ferulic acid is a growth promoter that increases N. oculata biomass. Addition of 100 mg L−1 ferulic acid to the culture medium led to an increase in cell density and specific growth rate (μ; day−1) of N. oculata. These values were 2.52 and 2.02 times higher, respectively, than those in the control group (without the addition of ferulic acid). Moreover, photosynthetic parameters, lipid and carbohydrate contents, and intracellular pigment contents (such as chlorophyll a and carotenoids) in the treated algal biomass tended to be higher than those in the control treatment. This study provides an initial scientific basis for the improvement of algal biomass productivity and metabolite production in safe and sustainable ways with naturally derived substances.