Influence of trace elements, tungsten and vanadium, on the in vivo nitrate reduction in azoola-anabaena symbiosis

ABSTRACT

Molybdenum [Mo] is an essential microelement for the induction of nitrate reductase in Azolla-plants. In Mofree cultures, tungsten [W] or vanadium [V] could not replace Mo. for nitrate reductase activity. Although- vanadium, up to a concentration of 0.01 ppm, enhanced the activity of nitrate reductase in Mo-containing cultures, tungsten showed an inhibitory effect. The suppression of nitrate reductase activity may, be related to the replacement of Mo co-factor or inhibition of the NADH-linked enzyme