The effect of salinity on survival, growth and ammonium liberation of cyanobacterium Nostoc sp.collected from paddy-fields of Golestan province at limited and unlimited carbon dioxide condition.

Cyanobacterium Nostoc sp can be considered as a potent strain both from antibacterial production ability and agricultural using at the future. So it seems logical to characterize this strain ecophysiologically include acclimation to salt stress. Soil samples were collected from paddy-fields during one year. Isolation and purification were done after soil colonization in BG0-11 medium. Inoculation of Nostoc sp. was done under 2 uE.m-2.s-1 illuminations, 28oC temperature, and without aeration. At the first step, wide ranges of sodium chloride salinities (25%, .5% and 1%) were treated.  Results showed that specific growth rate, reach to maximum at 0.5% salinity and though at other salinities survival could be remained but naturally at lower levels using DIC concentration system. The ammonium liberation showed the highest rate at 0.25% salinity condition, both in aeration and limited carbon dioxide conditions. This ability can be considered as a outstanding character from applied aspect.