Study on the Effect of Sodium Nitroprusside on Growth and Nitrogen Fixation in Blue-Green Algae Nostoc linckia

In this research, we investigated the effect of sodium nitroprusside (SNP) on growth, nitrogen fixation and some metabolites on Nostoc linckia . Culture medium with different concentrations of SNP (0, 0.01, 0.1 and 1 μM) was prepared. After 7, 14 and 21 days, samples were harvested and analyzed. Adding 1 μM SNP to culture medium decreased fresh weight significantly after 14 and 21 days. The alga treated with 0.01 μM SNP had lower heterocyst percent after 14 days. The amount of carotenoids increased with adding 1 μM SNP in 14-day-old cultures. The highest phycocyanin content was observed after 14 days in culture treated with 0.1 μM SNP. Increase in allophycocyanin content was observed by adding 0.1 and 1 μM SNP after 14 days and with 0.01, 0.1 and 1 μM SNP after 21 days. Treatment with SNP induced phycoerythrin content at 0.01 μM concentration after 21 days. The alga treated with 0.1 and 1 μM SNP had higher reducing sugar content after 14 days. However, in 21-day-old cultures all SNP concentrations showed decreased reducing sugar content in treated alga. The amount of soluble sugars was reduced by the highest SNP concentration after 7 days. SNP treatment could induce protein accumulation after 7 and 21 days by some concentrations, but in 14-day-old cultures SNP treatment had reduction effect on protein content. Nitrogenase activity considerably increased in culture exposed to SNP after 7 days. According to our results, positive effects of SNP on phycobiliproteins, protein content and nitrogenase activity and its inhibitory effect on heterocyst differentiation were important findings of this study.