Beneficial / Harmful Activities of Bacteria | Biology Class 11

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Economic-importance-of-bacteriaZoology | Biology
Economic Importance of Bacteria – Kingdom Monera
For: Science Class 11

Beneficial Activities
In Agriculture, the bacteria are mostly important for following reasons

  1. Nitrogen fixation : Plants cannot trap nitrogen from the atmosphere but bacteria can fix nitrogen and change it into nitrogenous compounds. The phenomenon is called nitrogen fixation. The bacteria, which fix atmospheric nitrogen, are called nitrogen-fixing bacteria. Some of the nitrogen fixing bacteria are found freely in soil are called free-living bacteria, eg. Clostridium and Azotobacter. Some of them are found in root nodules making association with leguminous plants called symbiotic bacteria, eg. Rhizobium.
  2.  Nitrification: Some bacteria convert ammonium compounds into nitrates in the soil. The process is called nitrification. The bacteria that take part in this process are called nitrifying bacteria, eg. Nitrobacter and Nitrosomonas.
  3. Ammonification: Some bacteria utilize proteins of dead bodies and convert it into amino acids. These amino acids are converted into ammonia by some bacteria. The process is called ammonification and the bacteria involve in the process are called ammonifying bacteria. Then the ammonia reacts with CO2 and H2O and gives ammonium carbonate which is absorbed by plants.
  4. Bacteria decompose dead bodies. They convert complex organic compounds into simple inorganic compounds. Therefore they’re called natural scavengers.
  5. Bacteria make the milk sour and produce flavor. They are responsible for coagulation of milk. E.g. Lacto bacillus.
  6. Bacteria convert sugary substances into alcohol, acids, acetones; etc the process is called fermentation.
  7. Bacteria also help to produce different types of enzymes like Amylase secreted from Bacillus, Protease from Bacillus, Streptokinase from Streptomyces.
  8. Bacteria are useful for vitamin production like Vitamin B (Cabalmin) is secreted from Pseudomonas, Vitamin B (Riboflavin) is secreted from Clostridium.
  9. They are important for antibiotic production like Terramycin from Streptomyces rimosus, Streptomycin from S. griseus, Neomycin from S. fradiae.
  10. They are also important to produce hydrogen commercially. During the process they ferment carbohydrate and hydrogen gas is produced.
  11. Bacteria decompose waste products.

Harmful activities

Some of the species cause food poisoning. They secret some toxic chemical substances on out food stuff which cause food poisoning, eg Staphylococcus and Clostridium.  Some are responsible for human diseases

Cholera: Vibrio cholera, Pneumonia: Staphylococcus pneumoniae
Diarrohea: Escherechia coli, Tuberclosis: Mycobacterium tuberclosis
Leprosy: M. leprae, Meningitis: Nisseria meningitides.

Some bacteria are responsible for plant diseases. Red stripe in sugarcane, Leaf streak in rice, black rot in cabbage and yellow rot in wheat are caused by Xanthomonas and Pseudomonas.

Posted By : Hari Prasad Chaudhary | Comment RSS | Category : Class XI, HSEB Notes
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