Transcriptome Analysis of Spirulina platensis sp. at Different Salinity and Nutrient Compositions for Sustainable Cultivation in Vietnam

This study investigates the suitability of Spirulina-Ogawa-Terui (SOT) culture media with various nutrition concentrations for the laboratory growth of salt-tolerant Spirulina platensis ST. Among the four saltwater mediums, 25% SOT media (42‰ salinity) demonstrated a satisfactory performance, with maximum absorbance at a wavelength 556 nm reading of 0.76. After 15 cultivation days, the protein, carbohydrate, lipid, phycocyanin, chlorophyll a, and carotenoid contents reached 48.73%, 22.14%, 7.32%, 10.23%, 0.53%, and 0.12% of the dry cell weight (DCW), respectively. The growth of S. platensis ST is influenced by the culture medium with a salinity of 13‰ and 52‰, as well as different nutrient compositions. Transcriptional sequencing revealed that the response of S. platensis ST to salt stress was mainly expressed by regulating the gene expression involved in metabolic pathways such as photosynthesis and signaling transduction. Under nutritional and salt stress, S. platensis ST responds by modulating the gene expression involved in the synthesis of vital molecules, for example, growth regulators and adenosine triphosphate (ATP) producers. In conclusion, this study provides an insight into enhancing the ability of S. platensis to tolerate salt stress. The findings indicate that future efforts in algal-based cultivation research in seawater should focus on increasing the productivity to develop a sustainable industry for biomass production.