Microbial Ecology | Role of microbes in ecosystem

Microbes As a Component of Ecosystem 

Microbial ecology is an association of microorganisms with one another and with their environment. Microorganisms effect the whole biosphere. They exist virtually on every part of planet earth including some in extreme conditions such as acidic lakes to deep ocean and from frozen environment to hydrothermal vents. 

The roles of microorganism in Ecosystem 

1: Generate oxygen in the atmosphere

Nearly all of the oxygen produced in earth today happens by bacteria in prehistoric period. In ocean, most of the oxygen producers are cyanobacteria (blue green algae).

2. Recycling nutrition stored in organic matters to inorganic form

Microbial decomposition of organic matters let out the minerals such as sodium, potassium, calcium etc and these minerals are bound up and made accessible for producers (green plants) to utilize. Without this recycling primary productive capacity of ecosystem would stop. Fungi are the most important decomposers of plant materials and are followed by bacteria in soil. 

3. Fix atmospheric Nitrogen into useable form

The only organisms which can remove N2 gas from the atmosphere and "fixing" it into a nitrogen form that is usable, ammonia and ammonium, (NH3, NH4), are bacteria.  The specific bacteria that can perform nitrogen fixation are dispersed throughout the groups including the cyanobacteria. All organisms which can fix nitrogen use the same mechanisms and the same enzymes. This capability probably evolved only once and early in the history of life.  Symbiotic nitrogen fixation costs the plant photosynthate to assist in the fixation and in NH3 assimilation. This cost could be from fifteen to thirty percent of the total carbon assimilated by the plant.  In fact, to fix one molecule of nitrogen, there is need of about 25 molecules of ATP. So it is expensive from the bacterial viewpoint, and which means that the plant must support that energy demand. In exchange for the plant receives nitrogen, which may otherwise be a limiting nutrient for the plant. 

(4) Allowing Herbivores to Intake Poor Quality Food

Most of the primary productivity is consumed by herbivores in the oceans. But in terrestrial systems, most of the primary productivity is not consumed by herbivores.  The reasons for this contradiction are: 

• Animals lack digestive enzymes which are capable of using cellulose and lignin and other structural plant compounds. 
•  The Plants often have anti-grazing toxins, aromatic resins, or thorns. 
• Most land plant tissue has deficiency in mineral nutrients (especially N and P) compared to the tissue in herbivore.

(5) Giving the Plant Roots Access to Nutrients in the Soil

As plant roots scavenge the soil, they create an area of nutrient depletion around themselves.  in order to get the new means of nutrients, the plant can either grow more roots and small root hairs (some as small as 10 um) or create an association with a fungus whose hyphae provide an even longer and well-organized absorptive structure. Most vascular plants can form such associations called "mycorrhizae".