Quantum yield alterations due to the static magnetic fields action on Arthrospira platensis SAG 21.99: Evaluation of photosystem activity

[Display omitted] •Magnetic fields increased the growth of Spirulina platensis.•Photosystem II activity was positively affected by magnetic field.•Magnetic field changed the chlorophyll fluorescence transients. Static magnetic fields (SMF) influence the metabolism of microorganisms, however, there is no knowledge explaining how SMF act in cells. This study aimed at evaluating the SMF (30 mT) effect on photosynthetic performance, growth and biomass composition of the cyanobacterium Arthrospira platensis SAG 21.99. A. platensis was cultivated under 30 mT applied for 1 h d−1 and 24 h for 10 d in glass bottles. SMF in both conditions increased cellular growth, achieving a 30% higher biomass concentration. SMF applied for 1 h d−1 increased the pigments and carbohydrate content. The quantum yield was used as an indicator of the photosystem II (PSII) activity and was shown to have been positively affected. SMF for 1 h d−1 had a significant effect on the OJIP curves. This is the first study that evaluated the photosynthetic activity in cyanobacteria cultures under SMF action.