Magnetic fields exhibit a positive impact on lipid and biomass yield during phototrophic cultivation of Spirulina sp.

Abstract

This study aimed to investigate the effects of magnetic field (MF) application (1, 12 and 24hday-1) to Spirulina sp. LEB 18 in different photosynthesis cycles (dark and/or light) during short (15days) and long periods (50days) of cultivation. MF application was performed via two sources: ferrite magnets and solenoids. At the end of cultivation, the biomass was characterized in terms of lipids, proteins, and carbohydrates. In the 15day cultures, the highest maximum biomass concentrations (2.06gL-1 and 1.83gL-1) were observed when 30mT was applied for 24h day-1 or 12h day-1 (on the light cycle), respectively. MF application throughout cultivation (24h day-1) for more than 30days is not recommended. In all conditions, there was an increase in the lipid concentration (from 14 to 45%). The protein profile suggested important changes in photosystems I and II due to MF application. Cell morphology was not altered by MF application. In conclusion, the effects on the metabolism of Spirulina sp. are directly related to the photosynthesis cycle and time period in which the MF was applied.