Doaa Bahaa Eldin Darwish

Spirulina platensis (SP) has a high impact on multidiscipline usage worldwide. Vitamins are considered as growth promoters due to their metabolic bio-regulating roles. This study was conducted to investigate the effect of vitamins: riboflavin (B2), thiamine (B1), and ascorbic acid (C) on SP growth and contents of pigments, phenols, and phytochemicals besides its antioxidant activities. Vitamins were added in different concentrations to Zarrouk’s medium and tested for their effects weekly for three weeks of spirulina cultivation. The results revealed that 25 mg·L −1 thiamine or riboflavin promoted the most significant contents of chlorophyll and carotenoids, respectively, after 14 days of cultivation. However, adding 10 mg·L −1 thiamine achieved the most significant increase in algal biomass yield and contents of chlorophyll, carotenoids phycocyanin, allophycocyanin, phycoerythrin, and phycobiliprotein after 21 days of cultivation. Qualitative analysis showed that both SP and SP supplemented with 10 mg·L −1 thiamine (SPt) for 21 days contain tannins and flavonoids but quantitative analysis approved that SPt recorded significant increase in phenolic and tannin contents. Moreover, SPt induced a significant increase of total antioxidant activity in vitro 1,1-diphenyl-1,2-picrylhydrazyl assay in comparison with SP. Vitamins especially thiamine added during SP culture could improve SP biomasses, pigments, and phytochemical contents and hence increased antioxidant capacity.