Outdoor and Indoor Cultivation of Spirulina platensis in the Extreme South of Brazil

Abstract

Water supplemented with 10% or 20% (v/v) of Zarrouk medium was used to cultivate Spirulina platensis in closed and open bioreactors under controlled conditions (30 °C, 32.5 μmol m−2 s−1, 12 h light/dark photoperiod) and in a greenhouse (9.4 to 46 °C, up to 2800 μmol m−2 s−1, variable day length photoperiod) using different initial biomass concentrations (X0) in the extreme south of Brazil (32.05° S, 52.11° W). Under controlled conditions the maximum specific growth rate (μmax) was 0.102 d−1, the biomass doubling time (td) was 6.8 d, the maximum dry biomass concentration (Xmax) was 1.94 g LD1 and the maximum productivity (Pmax) was 0.059 g L−1 d−1, while the corresponding values in the greenhouse experiments were μmax = 0.322 d−1, td = 2.2 d, Xmax = 1.73 g L−1 and Pmax = 0.112 g L−1 d−1. Under controlled conditions the highest values for these parameters occurred when X0 = 0.15 g L−1, while in the greenhouse X0 = 0.4 g L−1 produced the highest values. These results show that the cultivation of S. platensis in greenhouses in the extreme south of Brazil is technically viable and that the S. platensis inoculum and the concentration of Zarrouk medium can be combined in such a way as to obtain growth and productivity parameters comparable, or superior, to those occurring in bioreactors under controlled conditions of temperature, illuminance and photoperiod.