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 mÐ2 sÐ1, 12 h light/dark photoperiod) and in a greenhouse (9.4 to 46 ∞C, up to 2800 μmol mÐ2 sÐ1, 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 dÐ1, the biomass doubling time (td) was 6.8 d, the maximum dry biomass concentration (Xmax) was 1.94 g LÐ1 and the maximum productivity (Pmax) was 0.059 g LÐ1 dÐ1, while the corresponding values in the greenhouse experiments were μmax = 0.322 dÐ1, td = 2.2 d, Xmax = 1.73 g LÐ1 and Pmax = 0.112 g LÐ1 dÐ1. Under controlled conditions the highest values for these parameters occurred when X0 =0.15 g LÐ1, while in the greenhouse X0 = 0.4 g LÐ1 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.