Decrypting the Effects of Starvation and Excess of Nitrogen and Phosphorus on Nostoc calcicola

The physiological and biochemical behaviour of marine cyanobacterium (Nostoc calcicola) grown under starved and double the strength of nitrogen (N) and phosphorus (P) was studied. Culture grew in an Artificial Sea Nutrient III culture medium with five different concentrations of N and P, i.e., double the concentration of N (DN) or P (DP), starvation of nitrogen, (-)N and phosphorus, (-)P and combine deprivation of both nitrogen and phosphorus, (-)NP along with control. Growth rate and photosynthetic efficiency decreased under P starved condition alone, and combined starvation of N and P. Oxidative, and physiological stress was evidenced by increased ROS, MDA, and proline content level under starved conditions. Elevated activity of Ascorbic acid, SOD, CAT, and APX were also detected. In contrast, an increase in the growth rate and Fv/Fm ratio, along with low oxidative, osmotic stress, and antioxidant activity, was observed under double the strength of nitrogen and phosphorous. Our work demonstrated that P starvation alone and combine starvation of N and P affected the growth of N. calcicola, maybe due to oxidative damage (increased lipid peroxidation and carbonyl content). In contrast to nutrient-starved conditions, the growth rate of N. calcicola enhanced under DN and DP, followed by (-) N.