Question

1-Explane these process and the role of bacteria:

- Ammonification

- Nitrification

- Denitrification,

2- Identify three beneficial results of symbiotic nitrogen fixation

3- Outline the sulfur cycle, and explain the roles of microorganisms in this cycle

Answer 1

1.A. Ammonification

Animals and plants inorganic waste (NH2- amino) is converted to ammonium NH4+ by ammonification or mineralisation. Bacillus, Proteus, Clostridium are some bacteria which helps in the conversion of urea, uric acid , nitrogen of feces to ammonium which are all substrates for ammonification.Ammonium are used by microorganisms fo their metabolic process.

B. Nitrification

It is the oxidation of ammonia to nitrite and finally to nitrate.Autotropic bacteria and archea bacteria are involved in nitrification which is involved in nitrogen cycle in soil.During nitrification process CO2 is evolved which is used by microorganisms as carbon source for growth and for the production of energy by ATP synthesis.

C. Denitrification

Nitrate (NO3) is reduced to molecular nitrogen in denitrification.It occurs in the absence of oxygen,Microorganisms involved are thiobacillus, micrococcus and pseudomonas.Nitrates are easily soluble in atmospheric water and become toxic and also leads to algal bloom hence it is converted to Nitrogen.

2.Beneficial results of symbiotic nitrogen

There is an marked importance in the need of dood and energy and hence it has beneficial effect in agricultureFertlizer usage can be decreased.Increased cost of nitrate fertlizer fo farmers can be stopped and soil become more fertille by natural process . Fertlizer free healthy crop can be obtained which reduce the risk of diseases.

3. Sulfur cycle

It involves the mineralisation of organic sulfur to inorganisc forms hydrogen sulphide and elemental sulfur foolowed by oxidation to sulfate and finally reduction of sulfate to sulfide.Oxidation is done by green sulfur bacteria and purple sulfur bacteria . Sulfide is converted to metallo protiens .Sulfur cycle helps in reducing the deletrious effect of sulfur compounds , SO2 , H2S and other sulfur compounds in the environment.