Abstract
Salinity is one of the major environmental stresses affecting the growth, metabolism, and
survival of cyanobacteria. Nostoc muscorum, a filamentous nitrogen-fixing cyanobacterium,
exhibits remarkable adaptability to osmotic stress through various physiological and
molecular mechanisms. The present study aimed to characterize osmoregulatory genes
involved in salt stress tolerance in Nostoc muscorum. Cultures of Nostoc muscorum were
exposed to different concentrations of sodium chloride (NaCl), and the expression patterns of
selected osmoregulatory genes were analyzed. Growth rate, chlorophyll content, and
compatible solute accumulation were evaluated to assess physiological responses. Results
revealed significant upregulation of genes associated with compatible solute biosynthesis, ion
transport, and stress signaling under elevated salinity conditions.