1. Thiobacillus, Bacillus denitrificans and Microbacillus bacteria release nitrogen by breaking down soil nitrate in the process of denitrification. It causes lack of plant nutrients in the soil. Soil fertility decreases and crop production decreases.
2. Desulfovibrio bacteria break down sulfate salts in soil to release hydrogen sulfide gas in the desulfurization process. It causes great loss in plant nutrition.