| Cultures of mixed freshwater algae were grown in open batch reactors made up of modified BG-11 media that contained 0, 25, 50 or 100% of the suggested inorganic carbon content (0, 0.5, 0.1 and 0.2 g/L Na2CO3) to assess the subsequent production of the high-value product, sulfoquinovosyl diacylglycerol (SQDG). After 25 days of growth, the reactors were composed of primarily Oscillatoria growth. All four reactors exhibited a trend of increasing biomass and alkalinity with time, and an initial increase then decrease in pH. The total inorganic carbon (TIC) in all reactors exhibited a mirrored, opposite trend as pH, with an initial decrease then increase over time. A positive correlation was found between specific growth rate and amount of initial total inorganic carbon in the reactors. The Monod constants mu max and KS were estimated to be 0.025 hr-1 and 0.00215 mol/L C, respectively. At 95% confidence, the amount of initial TIC significantly affected the total lipid concentration, which increased with time in all reactors, and showed a trend of increasing total lipids with increasing initial TIC. Additionally, the initial TIC did not significantly affect the concentration of SQDG per mL culture or per mg dry biomass, or the percent of SQDG within the total lipids. SQDG content per mg biomass decreased with time for all TIC treatments. |
