African Journal of Biotechnology Vol. 6 (20), pp. 2363-2368, 18 October 2007   

ISSN 1684–5315 © 2007 Academic Journals        

Full Length Research Paper

Phosphate uptake kinetics and its regulation in N₂-fixing cyanobacterium Anabaena oryzae Fritsch under salt stress

Santosh Kumar Singh^1*, Vandana Pandey², and Kapil Deo Pandey³

¹Centre of Experimental Medicine and Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005, India.

²Department of Botany, Agrasen Kanya Autonomous Post Graduate College, Maidagin, Varanasi - 221 001, India.

³Algal Research Laboratory, Department of Botany, Banaras Hindu University, Varanasi-221 005, India.

*Corresponding author: E-mail: singhsk71@yahoo.com. Tel:  091-5422307549 (O) 091-9415389046 (Mobile).

Accepted 13 August, 2007

Phosphorous (P) starved cells of the cyanobacterium Anabaena oryzae showed higher phosphate uptake rates than P-sufficient cells. The P-uptake obeyed saturation kinetics. The Km value for P-deficient cells was lower (54.34 mM) than P-sufficient cells (82.64 mM) while V_max was higher in P-deficient and lower in P-sufficient cells. Salinity (NaCl) stimulated phosphate uptake significantly in the cyanobacterium which is followed by greater amount of P-accumulation in the form of polyphosphate bodies. Inhibition of P-uptake in P-deficient cells was 45% in dark grown compared to light grown cells. P-uptake was inhibited 52 and 85% in culture treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU; 10 mM) and carbonyl cyanide m-chloro phenylhydrazone (CCCP; 100 mM), respectively, suggesting that energy for uptake could be derived from oxidative phosphorylation and photophosphorelation.

Key words: Anabaena oryzae, metabolic inhibitors, phosphorus-uptake, salinity.