An investigation of the heterotrophic culture of the green alga Tetraselmis

The marine Prasinophyte Tetraselmis may be cultured under both mixotrophic (photoheterotrophic) and heterotrophic conditions. The growth rate was slightly lower, and pigment levels and lipid composition were radically affected on heterotrophic culture in 1 L fermenters. Total chlorophyll levels of dark grown cultures were less than 1 % of those observed in mixotrophically grown cells, the chlorophyll a : b ratio also decreased as did the carotenoid content. In addition, the total amounts of lipids including polyunsaturated fatty-acids were also lower in heterotrophically cultured cells: 6.4 mg g(-1) (dried alga) and 0.35 mg g(-1) (dried alga); as compared to 37.1 mg g(-1) (dried alga) and 18.5 mg g(-1) (dried alga), for cells grown in the light. However, gross morphology and final yield (>16 g l(-1)) were relatively unaffected. The algae produced were spray-dried and tested for their suitability as an aquaculture feed.