Structure and economic importance of bacteria

Structure of Bacteria:

The bacterial cell is surrounded by a cell wall. Cell wall is basically made up of polysaccharides, lipids and proteins. Cell wall contains a substance mucopeptide in which molecules of acetyl glucosamine and acetyl muramic acid join each other. In addition to this, Lalanine, D-alanine, D-glutamic acid and diaminopimelic acid are also found in cell wall.

In some bacteria, there is a slime layer outside the cell wall, which becomes hard to form a capsule. Capsule protects the bacteria under unfavorable condition. Capsule is made up of dextran, dextrin, levan, cellulose and other polysaccharides. Below the cell wall, there is a cell membrane, which is made up of phospholipids and lipoproteins.

The protoplasm of the cell is either granular or in the form of transparent fluid. Protoplasm contains glycogen, fats and volutin granules. Membrane-bound organelles like mitochondria, E.R., plastids, Golgi bodies, and lysosomes are absent. 70S ribosomes are freely distributed in the protoplasm. Plasma membrane is folded to form mesosomes, and participates in aerobic respiration. Enzymes of oxidative phosphorylation are located in plasma memberane.

There is no defined nucleus in the bacteria cell. Bacterial cell contains a naked circular DNA. It represents the bacterial chromosome. In addition to the main DNA, bacteria contain extrachromosomal genetic material called plasmid. Plasmid contains time 0.5-20% of the total DNA of the cell.

Economic Importance:

Bacteria has various uses in industries. The products obtained by bacterial activities cannot be chemically prepared. Bacteria are used for the preparation of the following items in various industries:

(i) Preparation of alcohol:

Ethyl alcohol and butyl alcohol are manufactured by the activity of Clostridium acetobutylicum in sugar solution.

(ii) Preparation of vinegar:

Vinegar is prepared by the activity of Acetobactor aceti in sugarcane juice.

(iii) Preparation of butter and cheese:

Butter and cheese are prepared by the bacteria, Lactobacillus lactis.

(iv) Curing of tea, coffee and cocoa:

The bacteria, Bacillus megatherium and Micrococcus condiscan help in curing and flavouring of tea, coffee and cocoa.

(v) Curing of tobacco:

Tobacco leaves are cured and flavoured by Bacillus megatherium.

(vi) Preparation of hemp fibres:

Fibres from the hemp are isolated after rotting the stems by the activity of Clostridium butyricum.

(vii) Preparation of leather and tanning:

The hairs and fats are removed from the skin by the action of bacteria in leather industries.