• Microorganisms are small living things that can
only be seen under high power microscope.
• Microorganisms include:
– Microscopic Fungi
– Microscopic Algae
3. Use of Micro-organisms in environment
1.1. Fixation of atmospheric nitrogenFixation of atmospheric nitrogen
2.2. Decomposition of organic wastes and residuesDecomposition of organic wastes and residues
3.3. Suppression of soil-borne pathogensSuppression of soil-borne pathogens
4.4. Recycling and increased availability of plant nutrientsRecycling and increased availability of plant nutrients
5.5. Degradation of toxicants including pesticidesDegradation of toxicants including pesticides
6.6. Production of antibiotics and other bioactive compoundsProduction of antibiotics and other bioactive compounds
7.7. Production of simple organic molecules for plant uptakeProduction of simple organic molecules for plant uptake
8.8. Complexation of heavy metals to limit plant uptakeComplexation of heavy metals to limit plant uptake
9.9. Solubilization of insoluble nutrient sourcesSolubilization of insoluble nutrient sources
10.10. Production of polysaccharides to improve soilProduction of polysaccharides to improve soil
4. Beneficial Microorganisms
• Food ProductionFood Production
• Soil Fertility and Bacteria andSoil Fertility and Bacteria and
• Combating PollutionCombating Pollution
• Antibiotic is chemical substance produced
by microorganisms that can kill or inhibit
the growth of other microorganisms.
• Antibiotics kill or inhibit other organisms
by interfering the metabolic process in the
bacterium that is not found in the host.
7. Food Production
C2H12O6 2C2H5OH + 2CO2 + energy
• Dairy Products: cheese, yogurt and butter
• Wine and bread: yeast (Saccharomyces
10. Combating Against Pollution
• Sewage Treatment.
• Oil spillage: Pseudomonas sp.can
digest the oil into harmless forms.
11. Sewage Treatment (1)
• Primary treatment
–In the sewage treatment plant the
solid organic matter is moved from
the sewage as sludge which may be
treated further to form fertilizer.
12. Sewage Treatment (2)
• Secondary treatment:
–The organic matter left in solution
and suspension are decomposed
rapidly by the added micro-
organisms (e.g. Bacillus,
Pseudomonas, Vorticella )
13. Sewage Treatment (3)
• Tertiary treatment:
–Finally all the micro-organisms are
killed by adding chlorine to the
effluent of the treated sewage which
can run into the rivers without
causing any pollution problems.
14. Water Treatment of HK
15. Microorganism in other
Vitamins (e.g. B2)
16. Harmful Organisms
• Causing Diseases.
• Food Spoilage.
This orange is covered by fungus.
Source from: Microbiology: Essentials and Application (2nd Ed.).
A child infected by mumps.
Source from : Microbiology: Essentials and Applications. (2nd Ed.)
17. Microorganisms and
• Pathogens are microorganisms that cause
disease in animals and crops.
• Any organisms that carry pathogen from
one living organism to another is called
• Virus cause diseases by disturbing the
homeostatic condition of the host cells.
19. Viral diseases
• Plant virus: Tobacco Mosaic Virus
• Human diseases caused by virus:
• Acquire Immune Deficiency Symptom.
• It is caused by Human Immunodeficiency
• Affects T-helper cells, making body defense
system unable to combat against disease.
• Mainly spread through sexual intercourse
and blood transfer.
21. HIV bud from the surface
an infected Helper T cell
22. Hepatitis B
23. Pathogenic Bacteria
• Pathogenic bacteria caused diseases by:
– destroy the body tissues of the host directly
– excrete toxins
– release toxin from cell wall after death
• Diseases caused by bacteria:
– Cholera, Typhoid fever
– Pneumonia, Whooping cough, Tuberculosis
– Gonorrhea, Syphilis
– Food poisoning
25. Fungal Diseases
-Fungal diseases are called mycoses which
affect the skin, nails and hair follicles
26. Methods to control the
spread of diseases
Personal and Public hygiene
27. Food Preservation
• Spoilage of food is caused by saprophytic
• Basic principle of food preservation:
– Killing the microorganisms in food;
– Stopping or inhibiting their growth.
Pickling of Food.
Source from: Biology: A Modern approach. (2nd Ed.)