Gene transcription and antioxidants production in Arthrospira (Spirulina) platensis grown under temperature variation

To investigate the transcription of selected antioxidants and relevant genes under varying temperature conditions, and to identify the optimum temperature for antioxidants production by Arthrospira platensis. The dry weight (DW), pigment production, antioxidants production and gene transcription were examined in A. platensis growing under three temperatures of 23, 30 and 37°C. The cyanobacterial DW was highest in the high temperatures (30 and 37°C), while the pigments, such as Chl a, carotenoids, C‐phycocyanin and total phycobiliprotein contents, showed their maximum value at 30°C. The total soluble protein and carbohydrate contents were highest at 30°C. Lipid peroxidation, as a marker for thermal stress, was high at 23°C, while higher temperatures remarkably reduced lipid peroxidation levels. Antioxidants activity was increased by 1·5‐fold at 30°C and temperature fluctuations induced the antioxidant enzyme activities. The transcriptional abundance of heat shock protein (HSP90), glutamate synthase (GOGAT), delta‐9 desaturase (desC), iron‐superoxide dismutase (FeSOD) and the large subunit of Rubisco (rbcL) genes was measured under the same temperatures. The optimal temperature for growth, biochemical constituents and antioxidants of A. platensis is 30°C while some antioxidant enzyme activity increased at lower and higher temperatures. The study showed the significance of temperature for growth, enzymatic and non‐enzymatic antioxidants and gene expression in A. platensis. This contributes to the knowledge of culturing A. platensis to harvest specific antioxidants or as an antioxidant‐rich food source.