Growth, photosynthetic pigment proteins responses and transcriptome analysis provide insights into survival strategies against short-term cold stress in the blue-green algae, Arthrospira

Arthrospira species are widely cultivated due to their high nutritional value as a food supplement. The fluctuating temperature strongly influences the cultivation system for Arthrospira mass production. To reveal the underlying mechanisms of coping with temperature stress to adopt measures of harm reduction, we analyzed changes in growth, photosynthetic pigments and the transcriptome of Arthrospira sp. TJSD091 exposed to short-term cold stress. The photosynthetic pigments decreased significantly under cold temperature stress conditions, and so as the cells' dry weight. A total of 1294 genes were expressed differentially. Pathway analysis revealed 473 differentially expressed genes were identified in 32 KEGG pathways, of which 309 genes (65.33 %) are involved in the most affected metabolic pathway. The most sensitive metabolic pathways in response to cold stress involved energy metabolism, carbohydrate metabolism and photosynthesis proteins. The key hub regulatory genes were perceived as cyaA and genes related to two-component signal transduction systems. The genes regulated diverse metabolic functions to survive and grow. The increased respiration provided essential energy for basic motility maintenance under cold stress. The down-regulation of genes involved in photosynthesis, glycolysis, Calvin cycle and citrate cycle supported the low biomass production of the blue-green algae. The results provide a basis for revealing the survival mechanism of the blue-green algae to withstand cold stress at the gene transcription level.