Influence of Different Culture Conditions on Yield of Biomass and Value Added Products in Microalgae

Abstract

Microalgae viz., Botryococcus, Haematococcus and Dunaliella, were studied for their adaptability to different culture conditions. Botryococcus strains of indigenous origin and culture collection centres were studied for their growth, hydrocarbon and lipid profile and for their biomass yields under different bicarbonate concentrations. Growth of Haematococcus was compared in autotrophic (ambient and enriched CO 2 atmosphere) and heterotrophic culture conditions. Influence of ammonium salts, urea and commercial fertilizers as nitrogen source under autotrophic conditions and different amino acids as nitrogen source under heterotrophic culture conditions, was studied on growth and astaxanthin content of Haematococcus. Influence of different salinities was studied on growth and -Carotene content of Dunaliella in AS100 and De Walnes media. Results indicated that Botryococcus strains varied in their biomass yields (0.25-2 g L -1 ), hydrocarbon content (15-60% w/w) and lipid content (15-30%, w/w). An indigenous strain was able to grow at all the tested concentra- tions of bicarbonate with maximum biomass yield at 0.25 g L -1 . The growth rate of Haematococcus was higher in heterotrophic medium with a cell count of 41-44 × 10 4 on 5 th day after inoculation. The supplementation of autotrophic medium with 2% CO 2 led to a 4-fold increase in cell count. Use of DAP as nitrogen source showed a 20% increase in yield of encysted biomass. Both DAP and Suphala led to astaxanthin productivity of 46-48 g L -1 . Haematococcus was able to utilize all the amino acids at tested concentrations in heterotrophic culture conditions. Enhanced growth of Dunaliella was observed at 1.0 M NaCl concentration in both the AS 100 and De Walnes media while 2.0M NaCl in De Walnes medium showed higher -carotene content (45.6 mg g -1 ).