nostoc punctiforme nostoc punctiforme nostoc punctiforme is a species of filamentous cyanobacterium. under non-limiting nutritional environmental conditions, its filaments are composed of photosynthetic vegetative cells; upon nutrient limitation, some of these cells undergo differentiation into heterocysts, akinetes or hormogonia. nostoc punctiforme scientific classification domain: bacteria phylum: cyanobacteria class: cyanophyceae order: nostocales family: nostocaceae genus: nostoc species: n. punctiforme binomial name nostoc punctiforme(kütz.) har. n. punctiforme is one of the nostoc strains able to maintain diazotrophic symbiosis with higher plants such as the bryophytes anthocerus punctatus and blasia pusilla, water ferns from the genus azolla, the cycads macrozamia spp., and the angiosperm gunnera. applications: modified nostoc punctiforme intein (npu dnae split intein) is used for a self-cleaving protein purification (e.g. icaptag™).