Fed-batch mixotrophic cultivation of Arthrospira (Spirulina) platensis (Cyanophycea) with carbon source pulse feeding

A preliminary attempt is presented to remove glucose, acetate and propionate, selected as model organic pollutants, by fed-batch Arthrospira platensis mixotrophic cultivation. Cultures performed at 30 °C by pulse feeding glucose under conditions of continuous 2.0 klux light were shown to ensure a final biomass concentration (1.3 g l -1 ) about 40% higher than alternating 12 h light and 12 h darkness. Additional tests, carried out using continuous illumination, demonstrated that the average specific growth rate of A. platensis, calculated during the start-up, was on glucose (0.096 d -1 ) higher than on acetate (0.074 d -1 ), propionate (0.068 d -1 ) or a bicarbonate/carbonate solution taken as a reference of autotrophic metabolism (0.072 d -1 ). Nitrate and phosphate removals, either experimentally determined or theoretically estimated by material balances, evidenced the biotic nature of both phenomena.