An Assay for Environmental Nitrate That is Based on its Reduction to Nitrite by Nitrite Reductase Deficient Neurospora Mycelia

A simple, sensitive, reliable and inexpensive assay for environmental nitrate in solution, based on its reduction to nitrite in vivo, by nitrite reductase deficient Neurospora mycelia, is described. Water samples are amended to contain ingredients necessary for the growth of Neurospora except nitrogen, which is provided by the endogenous nitrate. Mycelia are incubated with this amended water sample and allowed to convert the endogenous nitrate to nitrite. The nitrite is then measured colourimetrically.