Study on the transcriptome of Vietnam cyanobacteria Spirulina platensis ST cultured at different salinity and nutrition composition supported by Senior Researcher, code NVCC 08. 04. 22-23 (Prof. Dr. Dr. Dang Diem Hong).

In this project demonstrated the selection of SOT culture media (salinity 30ppt) with different nutrition concentrations suitable for cultivation of salt-tolerant cyanobacteria Spirulina platensis strain ST under laboratory conditions. Among the four studied saltwater medium, strain ST grew best in 25 percent of SOT media (30 ppt salinity) with optical density at 556 nm (OD556 nm) reaching a maximum of 0.76 after 15 days of cultivation. The content of proteins, carbohydrates, lipids, phycocyanin, chlorophyll a and carotenoids reached 48.73 percent of dry cell weight (DCW); 22.14 percent DCW; 7.32 percent DCW; 10.23 percent DCW; 5.32 mg/g DCW and 1.17 mg/g DCW after 15 days of cultivation. The culture medium with salinity 0ppt and 30ppt and different nutrient composition affected the growth of S. platensis ST., 5 samples of Spirulina platensis ST which were cultured at different conditions for salinity and nutrition composition were evaluated for physiological and biochemical characteristics and transcriptional sequence analysis by llumina system. The transcriptome sequences of these samples were then aligned with the reference genome, evaluated gene expression quantification, analyzed differentially expressed genes, annotated DEGs with Gene Ontology and KEGG. Our obtained results showed that among the four studied saltwater medium, strain ST grew best in 25 percent SOT media (30 ppt salinity) with high content of proteins, carbohydrates, lipids, phycocyanin, chlorophyll a and carotenoids after 15 days of cultivation. The response of S. platensis to salt stress was mainly archived by regulating gene expression involved in many metabolic pathways as photosynthesis, signaling transduction and etc.; in while, the response of S. platensis to salt in combination with the nutrient stress was by regulating gene expression involved in the synthesis of vital molecules as growth regulator and ATP producer and in the cell growth and protein content. In summary, this study provides an insight for further improving salt stress tolerance of Spirulina platensis cyanobacteria.