Effect of temperature and LEDs on the growth, pigment content and biological activities of Spirulina maximacultured in brackish water

Abstract

Temperature and light are important factors for the growth of photoautotrophic microorganisms such as Spirulina maxima; therefore, proper control of these conditions in S. maxima’s culture will help to enhance production efficiency. This study aims to determine the effect of temperature (in the range of 15-40^oC) and LED lights (white and red) on the growth, pigment content and biological activities of S. maxima biomass. The findings showed that the most suitable temperature range for growing S. maxima was about 25-30ºC. After ten days of cultivating with both white and red LEDs, the highest dry weight biomass reached 1.705 and 1.891 g/l, respectively. However, the ability to accumulate pigments
like phycocyanin, chlorophyll, and carotenoids in the dry biomass cultured under the red LEDs was 152.0, 6.6, and
3.0 mg/g, respectively, which are higher than that under the white LEDs (118.0, 5.5, and 2.9 mg/g, respectively). In
addition, S. maxima extracts from the biomass cultured under the red LEDs exhibited antibacterial activity against two pathogenic strains Staphylococcus aureus VTCC12275 and Escherichia coli VTCC12272, as well as the ability to scavenge free radicals by DPPH, are also better than those grown under the white LEDs.