Proteome Analysis of Nitrogen Starvation Responses in Cyanobacteria

Carbon dioxide is one of the principle pollutant warming the earth. In the global effort to combat the climate change, several CO 2 capture and storage technologies are deliberated. In the past 150 years, anthropogenic activities have pumped enough carbon dioxide into the atmosphere to raise its levels to 400 ppm, higher than they have been for hundreds of thousands of years. Microalgae can provide solutions to the twin challenges of energy security and environmental pollution. Environmental factors play a significant role and control the availability of CO 2 which affect carbondioxide concentrating mechanism activity. In this study, the effects of nitrate feeding on microalgal growth and related CO 2 fixation were evaluated, as an affinity to increase carbon fixation. On nitrate depletion, the growth of cyanobacterial cells declined. The increasing concentration of nitrate from 5 g/L to 20 g/L rapidly increased the biomass of Phormidium animale from (0.51 mg/ml) to (0.80 mg/ml) on the 20 th day of growth. Low molecular weight protein bands were suppressed in nitrate stress condition due to decrease in metabolism and photosynthesis in cyanobacterial isolates. High intensity protein bands of molecular weight 29 – 30 kDa was noted in higher nitrate concentration but in low nitrate concentrations have less intense bands in Anabaena sp. A number of faint bands was noted in Nostoc sp. These results indicated that the protein profile in the carbon concentrating mechanism from growth to protein expression of carbonic anhydrase and RuBisCo.