Batch and fed-batch uptake of carbon dioxide by Spirulina platensis

The ability of Spirulina platensis LB2340 to grow on carbon dioxide and mixtures of bicarbonate/carbonate was compared under light irradiation conditions simulating those naturally present in temperate latitudes. Batch tests performed at 25 degreesC in open tanks suggested that inorganic carbon is preferentially assimilated in the form of bicarbonate and that its utilization efficiency depends either on pH or final biomass level. The efficiencies of photosynthesis (PE) and carbon utilization (CUE) on carbon dioxide reached maximum values ( >6 and 38%) after 4 and greater than or equal to 7 days, respectively. They then progressively decreased. Fed-batch tests performed on carbon dioxide showed the highest values of biomass concentration (1.50 g l(-1)) and PE (1.1%) under pseudo steady-state conditions at 0.251 per day feeding rate. (C) 2003 Elsevier Science Ltd. All rights reserved.