Changes in nitrate reductase activity of chlorella vulgaris grown on horse waste

The rate of absorption of various soluble organic-N fractions by Chlorella cells grown on 0.2% horse dung extract increased by increasing experimental period. This was accompanied by inhibition of nitrate reductase[NR] activity and decrease in the rate of nitrate disappearance. Transferring waste-precultured Chlorella cells to nitrogen-deficient medium resulted in a great depression of NR activity, while addition of NO[3]to the medium increased the activity. The main effect of the organic-N fraction of horse dung extract was on the NR activity rather than on NO[3] uptake or nitrate reductase synthesis in Chlorella cells