Role of Microorganisms in Environment

Role of Microorganisms in Environment
Microorganisms in Soil
The important characterizes of soil microorganisms are:
1- Microorganisms in the soil are important to us in maintaining soil fertility / productivity, cycling of nutrient elements in the biosphere and sources of industrial products such as enzymes, antibiotics, vitamins, hormones, organic acids etc. At the same time certain soil microbes are the causal agents of human and plant diseases.
2- Cultivated soil has relatively more population of microorganisms than the fallow land, and the soils rich in organic matter contain much more population than sandy and eroded soils. Soil fertility depends not only on the presence of inorganic and organic substances, but also on the presence of various species of micro-organisms which influence the qualitative composition of the soil.
3- The number of microorganisms in the soil depends on the extent of contamination with feces and urine, and also on the nature of treating and fertilizing the soil. For example, ploughed soil contains 2.5 times more microbes than forest soil.
4- Saprophytic spores (B. cereus. B, meguterium, etc.) survive for long periods in the soil. Pathogenic bacteria which do not produce spores due to lack of essential nutrients, and also as a result of the lethal activity of light, drying, antagonistic microbes, and phages do not live long in the soil (from a few days to a few months).