CHEMICAL NUTRIENT REQUIREMENTS

 CHEMICAL NUTRIENT REQUIREMENTS

·     Microbial nutrients are the substances that are acquired from the environment and used for growth and metabolism of microorganisms.

·     Microbial cell composition shows that 95 % of cell Dry weight is made up of a few major elements:

ü  Carbon

ü  Oxygen

ü  Hydrogen

ü  Nitrogen

ü  Sulfur

ü  Phosphorous

ü  Potassium

ü  Calcium

ü  Magnesium

ü  Iron

1) Macronutrients or Macroelements

·    Macronutrients or Macroelements are required by microorganisms in relatively large amounts.

·       Macronutrients usually help to maintain the Cell structure and Metabolism.

·       Macronutrients exist in the cell as Cations.

·       Four Macronutrients or Macroelements required for Microbial growth are a) Potassium, b) Calcium, c) Magnesium and d) Iron.

a)   Potassium - Required for activity by a number of enzymes, including some of those involved in Protein synthesis.

b)   Calcium - Contributes to the heat resistance of bacterial Endospores.

c)  Magnesium - Serves as a Co-factor for many Enzymes, complexes with ATP, and stabilizes Ribosomes and Cell membranes.

d)   Iron - Part of Cytochromes and a Co-factor for enzymes and electron-carrying proteins.

2) Micronutrients or Trace elements

·       Micronutrients are the nutrients which are needed in trace or small amounts.

·       Micronutrients help for Enzyme function and maintaining Protein structure.

·       Micronutrients exist in the cell as Cations.

·      Four Micronutrients or Trace elements required for Microbial growth are a) Manganese, b) Zinc, c) Cobalt and d) Molybdenum.

a) Manganese - Aids many enzymes catalyzing the transfer of phosphate groups.

b) Zinc - Present at the active site of some enzymes but is also involved in the association of regulatory and catalytic sub-units in Escherichia coli Aspartate Carbomoyl Transferase.

c)    Cobalt - Component of Vitamin B12.

d)   Molybdenum - Required for Nitrogen fixation.

3) Carbon Requirements

·       Besides water, one of the most important requirements for microbial growth is Carbon.

·   Carbon is the structural backbone or skeleton of living matter. It is needed for all the organic compounds that make up a living cell.

·       Half (50 %) the dry weight of a typical bacterial cell is Carbon.

·   Chemoheterotrophs get most of their Carbon from the source of their energy - Organic materials such as Proteins, Carbohydrates and Lipids.

·       Chemoautotrophs and Photoautotrophs derive their Carbon from Carbon-di-oxide.

4) Nitrogen Requirements

·       The syntheses of DNA and RNA also require Nitrogen and some Phosphorus.

·       Protein synthesis requires considerable amounts of Nitrogen as well as some Sulfur.

·       Nitrogen makes up about 14 % of the dry weight of a bacterial cell.

·       Organisms use Nitrogen primarily to form the Amino group of the Amino acids of Proteins.

·   Some important bacteria, including many of the photosynthesizing Cyanobacteria, use gaseous Nitrogen (N₂) directly from the atmosphere. This process is called Nitrogen fixation.

5) Sulfur Requirements

·      Sulfur is used to synthesize Sulfur-containing Amino acids and Vitamins such as Thiamine and Biotin.

·     Important natural sources of Sulfur include the Sulfate ion, Hydrogen sulfide and Sulfur-containing amino acids.

·       Protein synthesis requires considerable amounts of Nitrogen as well as some Sulfur.

·       Sulfur and Phosphorus together constitute about another 4 %.

6) Phosphorous Requirements

·  Phosphorus is essential for the synthesis of Nucleic acids (DNA and RNA) and the Phospholipids of cell membranes.

·       Phosphorous is also found in the energy bonds of ATP.

·       A source of Phosphorus is the Phosphate ions.

·       Sulfur and Phosphorus together constitute about another 4 %.