ISOLATION AND CHARACTERIZATION OF SALINITY RESISTANT MUTANT OF A NITROGEN-FIXING CYANOBACTERIUM, ANABAENA-DOLIOLUM

Sodium chloride, up to 20 mmol/l concentration, had a positive effect on acetylene reducing activity and photosynthetic oxygen evoluation of a paddy field cyanobacterium, Anabaena doliolum. Beyond 20 mmol/l level of salinity adverse effects appeared. A mutant resistant to 200 mmol/l NaCl was isolated by nitrosoguanidine mutagenesis. The mutant, NaCl-R200, showed about 20-25% more nitrogenase activity and photosynthetic oxygen evolution than the parent. Better capacity of nitrogen fixation and photosynthesis possibly could help the mutant in synthesis of osmotic stabilizer to resist the salinity stress.