then this micronutrient might be instrumental in altering the cell surface for the survival of cyanobacteria under stress conditions. The effect of B nutrition on the sensitivity of Anabaena to detergent (SDS) or hyperosmotic stress (PEG and NaCl) was assayed under non-diazotrophic growth conditions. Anabaena was cultivated in multiwell plates containing BG11 liquid media with increasing concentrations of SDS, PEG, or NaCl, at different B concentrations (see Section 3).