RIBOFLAVIN CONTENT OF 6 SPECIES OF MICROALGAE USED IN MARICULTURE

Concentrations of riboflavin -a vitamin essential for maricultured animals-were measured in six species of microalgae commonly used in mariculture. These were two diatoms (Chaetoceros gracilis, Thalassiosira pseudonana); two prymnesiophytes (Isochrysis sp. (clone T.ISO), Pavlova lutheri); one chlorophyte (Nannochloris atomus) and one eustigmatophyte (Nannochloropsis oculata). Cultures were analysed during both logarithmic and stationary growth phase. The proportions of riboflavin (mug g-1 dry weight) during logarithmic growth-phase ranged from 20 (T. pseudonana) to 40 mug g-1 (Isochrysis sp. T.ISO). With the onset of stationary phase, the proportion of riboflavin increased in all species; the increase was most dramatic in cultures of C gracilis, T pseudonana and N. atomus (2- to 3-fold). Chaetoceros gracilis contained more riboflavin (106 mug g-1) than all other species (48 to 61 mug g-1). Despite the differences in the composition of the different microalgae, across both logarithmic and stationary growth-phases, all species should provide a rich source of riboflavin for maricultured animals.