PRELIMINARY AND COMPARATIVE STUDIES ON THE CULTIVATIONS OF DUNALIELLA SALINA BETWEEN OUTDOORS AND IN THE PHOTOBIOREACTOR

Abstract

ABSTRACT Open pond cultivation of algae is greatly affected by environmental factors, such as temperature, light, native predator, etc., which makes the controllability of aquiculture very poor. In the present research, a novel small helix‐tube photobioreactor (PBR) with a volume of 1 L was designed according to the universal principles of PBR. The specific surface area of the reactor reached 62 m2/v, much more than 10 m2/v of the open pond cultivation conditions. A comparative study on the cultivation of algae between the PBR and outdoors was carried out. A species of marine microalga, Dunaliella salina, was used as a model organism in this study. At the end of the logarithmic phase after 12 days, the biomass of D. salina in the PBR was 290 mg/L, and the content ofβ‐carotene reached 28.38 mg/L, while the biomass and content ofβ‐carotene in outdoor cultivation were 250 and 22.87 mg/L, respectively. These results indicated that cultivation of algae in the PBR was more effective than that outdoors.PRACTICAL APPLICATIONSDespite the success of open systems, future advances in microalgal mass culture will require closed systems as the algal species of interest do not grow in highly selective environments. Furthermore, many of the new algae and algal products must be grown free of potential contaminants such as heavy metals and microorganisms. A helpful research was conducted in the present study to make a spiral‐tube photobioreactor (PBR) for the cultivation of Dunaliella salina in order to increase the output of β‐carotene. The designed PBR is based on the universal principles for such bioreactors, and is intended to overcome problems with outdoor cultivation. The advantages of PBRs in the light utilization ratio are obvious, including enhanced growth performance and higher biomass quality through cultivation in closed PBRs. It is hoped that this design of closed PBRs will be commercialized in the near future.