Stimulatory Effects of Sodium Tungstate on the Growth of the Blue-green Alga, Anabaena doliolum

Abstract

Sodium tungstate increases the growth rate and final growth yields of molybdenum-starved cultures. Also, concentrations of tungstate much higher than of molybdenum are non-toxic and exert growth promotory effect. like molybdenum, tungsten effects are stimulatory on inorganic and molecular nitrogen, whereas on amino acids as nitrogen source, the effects are toxic. The chelator 8-hydroxyquinoline nullifies the growth promotory effect of both tungsten and molybdenum. Effects of both the elements on heterocyst size and frequency are also comparable. Implications of these findings are discussed in relation to the possible role of tungsten.