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4.2 Economic Importance of Bacteria
Introduction
Microscopic, single-celled organisms found everywhere.
Play crucial roles, both beneficial and harmful, in medicine, agriculture, and industry.
(a) Useful Role of Bacteria: Medicine
Antibiotics:
Kill or inhibit other microorganisms.
Examples:
Streptomycin (
Streptomyces griseus
), Bacitracin (
Bacillus subtilis
).
Serums:
Provide passive immunity with pre-formed antibodies.
Example:
Anti-tetanus serum (ATS).
Vaccines:
Stimulate active immunity.
Example:
BCG vaccine (for tuberculosis).
(a) Useful Role of Bacteria: Agriculture
Vital for soil fertility and plant growth, primarily through the
Nitrogen Cycle
.
Nitrogen-Fixing Bacteria:
Convert atmospheric N₂ to ammonia.
Symbiotic:
Rhizobium
(in leguminous plants).
Free-living:
Azotobacter
,
Clostridium
.
Nitrifying Bacteria:
Convert ammonia to nitrates (e.g.,
Nitrosomonas
,
Nitrobacter
).
Denitrifying Bacteria:
Convert nitrates back to N₂ (e.g.,
Pseudomonas denitrificans
).
(a) Useful Role of Bacteria: Industry
Curing of Tea:
Fermentation process develops flavor and aroma (e.g.,
Bacillus megaterium
).
Tanning of Leather:
Help in decomposition of non-collagenous proteins and fats in hides.
(b) Harmful Role of Bacteria: Spoilage of Food
Decompose organic matter, making food unfit for consumption.
Produce foul-smelling compounds.
Examples:
Clostridium botulinum
(botulism in canned foods).
Salmonella
,
E. coli
(food poisoning).
Lactobacillus
(souring milk).
(b) Harmful Role of Bacteria: Diseases
Diseases in Humans
Cholera:
Vibrio cholerae
(severe diarrhea).
Typhoid:
Salmonella typhi
(fever, intestinal issues).
Tuberculosis:
Mycobacterium tuberculosis
(lungs).
Tetanus:
Clostridium tetani
(muscle spasms).
Diseases in Plants
Citrus Canker:
Xanthomonas axonopodis
.
Fire Blight:
Erwinia amylovora
.
Crown Gall:
Agrobacterium tumefaciens
.
(b) Harmful Role of Bacteria: Bio-weapons
Microorganisms or toxins deliberately released to cause disease and death.
Pathogenic bacteria can be cultivated and weaponized.
Examples:
Bacillus anthracis
(Anthrax).
Yersinia pestis
(Plague).