Towards sustainable spirulina farming: Enhancing productivity and biosafety with a salinity-biostimulants strategy

Abstract

Arthrospira platensis (spirulina) is pivotal to the global microalgae industry, valued for its nutritional and bioactive properties. However, its sustainable production is challenged by freshwater scarcity and biological contaminants. This study introduces a salinity-biostimulants strategy to adapt a freshwater spirulina strain, CBD05, to near-seawater salinity (3 %). Exogenous glycine betaine (GB) and nitric oxide (NO), typical salinity enhancers, improved biomass productivity (0.36 g L−1 d−1), C-phycocyanin (C-PC) yield (83 mg L−1 d−1), and the economic output-to-input ratio was significantly enhanced. Metabolomic analysis linked salt tolerance to elevated amino acid accumulation, protein synthesis, and glycolysis, while transcriptional evidence highlighted enhanced carbon fixation and nitrogen assimilation towards C-PC synthesis upon addition of GB and NO. This strategy also demonstrated high resistance to Microcystis aeruginosa, a common contaminant in open systems. It provides a sustainable and cost-effective approach for industry-oriented spirulina production in freshwater-limited regions.