Effect of cultural conditions on biomass and nitrate reductase activity in six strains of anabaena isolated from paddy field soils of Ganjam (Orissa)

Cyanobacteria offer an economically and ecologically sound alternative to chemical fertilizers forrealizing the ultimate goal of increased productivity, especially in rice cultivation. There is however, agrowing concern about the adverse effects of indiscriminate use of chemical fertilizers on soil productivityand environmental quality. A comparative study between the NR activity and biomass of six Anabaenastrains isolated from paddy field soils of Ganjam district in presence of pH, temperature, copper&molybdenum, NaNO3, NH4Cl, and Urea is being conducted to present a situation where NR activity andbiomass may be affected under varied concentration. Maximum NR activity was observed in Anabaena sp.at pH 8.5 and 35oC temperature while Anabaena circinalis showed minimum activity in same concentration.Biomass content was maximum in Anabaena variabilis at pH 8.5 where as at temperature 35oC in Anabaenaflos-aquae and minimum biomass observed in Anabaena iyengarii at same concentration. NR activity inrelation to copper was maximum in Anabaena sp. at 2 ıg/l while minimum in Anabaena circinalis at sameconcentration. At 0.5μg/l molybdenum content in the culture medium showed maximum NR activity inAnabaena sp and reduced in all strains with increase of concentration. Anabaena flos-aquae showedminimum NR activity at 0.1mM concentration of NaNO3 while Anabaena circinalis showed minimum NRactivity at same concentration of NH4Cl. The NR activity was observed minimum at 3mM concentration ofUrea in A. cylindrica. The activity of NR and biomass in all the strains was influenced by external NH4-and NO3 +and Urea concentration.