Culture of Spirogyra sp. in a flat-panel airlift photobioreactor.

Spirogyra is a green filamentous freshwater algae on which recent studies reveal several promising properties and potential application possibilities in biotechnology. However, little is known about cultivation of Spirogyra and even less about large-scale cultivations in closed growth systems. Therefore, the aim of the present study was to elaborate the growth kinetics of Spirogyra sp. in a commercially available and scalable photobioreactor. For this purpose, Spirogyra sp. was grown indoors in distinct flat-panel airlift photobioreactors equipped with culture-flow directing installations. Hereby, special attention was laid on light administration and specific light availability and it was found that Spirogyra sp., in combination with the photobioreactor in question, required high photon-flux densities (100 µmol m-2 s-1 gDW-1) for maximum proliferation which is in accordance with its abundance in epipelagial waters in nature. Applying photon-flux densities of up to 1400 µmol m-2 s-1, a maximum volumetric productivity and final biomass concentration of 1.15 gDW L-1 day-1 and 14.28 gDW L-1 were achieved, respectively, the highest to be reported for the alga. To the knowledge of the authors, this is the first report on the growth of Spirogyra in a flat-panel photobioreactor.