What is the role of microorganisms in nature and human life?

Due to their vital activity, decomposition and mineralization of animal and plant residues occurs. With the help of soil microorganisms, the biological cycle of carbon, nitrogen, phosphorus, the fixation of molecular nitrogen of the air entering the soil, and the process of its self-cleaning are carried out.
Microorganisms living in water participate in the cycle of sulfur, iron and other elements, decompose organic matter of animal and plant origin, and provide self-purification of water in reservoirs.
However, not all microorganisms are beneficial to humans. Some microorganisms are opportunistic or pathogenic for humans and animals. Some microorganisms cause damage to agricultural products, lead to depletion of soil in nitrogen, cause pollution of water bodies, accumulation of toxic substances (for example, microbial toxins).