Microbial fixation of nitrogen in the presence of lanthanum sulphate

The effect of lanthanum sulphate on five Azotobacter strains (4A7, 10, 5A2, 5A1, and 3A3) isolated from Allahabad soil consists in a considerable increase in the nitrogen fixation, carbon consumption and in the amount of nitrogen fixed in mg per g of carbon consumed. The presence of 200 microM, 300 microM and 400 microM lanthanum sulphate in culture media increases the fixation of nitrogen by all the nitrogen fixers significantly.