Microbiology Fundamentals

Micro-organisms

• Micro-organisms are unicellular or multicellular organisms, not clearly visible to the naked eye and were previously studied in grade 8
• Micro-organisms are found in the environment and inside the body
• Most micro-organisms are favorable to humans and other organisms; however, some can be harmful
• They are widespread on Earth, possessing a simple structure and rapid reproduction rate
• Micro-organisms adapt to different environmental conditions and modes of nutrition
• Both unicellular and some multicellular organisms fall under the micro-organism category
• Micro-organisms can be categorized into bacteria, fungi, algae, and protozoa
• Viruses, which exist between living and non-living entities, are also studied within micro-organisms

Characteristics and Examples of Micro-organism Categories

• Bacteria: Unicellular and microscopic with different body shapes, widely spread; examples include: Lactobacillus bulgaricus for milk products, Bacillus anthracis for anthrax, and Acetobacter aceti for vinegar
• Fungi: Unicellular or multicellular, some reproductive organs visible (e.g., mushroom), thrive on moist surfaces; examples include: Mucor on bread and Saccharomyces (yeast)
• Protozoa: Unicellular and microscopic, use cilia/pseudopodia/flagella for locomotion, live in aquatic environments and other organisms; examples include: Amoeba, Paramecium, Euglena, and Plasmodium
• Algae: Unicellular or multicellular, filamentous or thallus body forms, microscopic algae floating on water surfaces (phytoplankton), possess chlorophyll for photosynthesis; examples include: Chlamydomonas, Spirogyra, and Diatoms
• Virus: Electron microscopic, display living/non-living characteristics, multiply inside living cells, lack cellular organization, don't show respiration/growth; examples include: Influenza virus, HIV, Ebola virus, and Dengue virus

Environments and Substrates of Micro-organisms

• Micro-organisms inhabit all ecosystems where other organisms survive
• They are found in soil, water, and up to 6 km in the atmosphere
• Micro-organisms survive on/within plants and animals
• Specific substrates for micro-organism growth include: meat, fish, fruits, vegetables, human skin, mouth, alimentary canal, and urinary tract
• Microbes endure extreme conditions like hot water springs, salt marshes, and liquids like petrol/diesel

Effects of Micro-organisms

• Micro-organisms have been used in various industries and are beneficial for environmental equilibrium
• Some are harmful to humans as pathogens and food spoilers

Beneficial Effects of Micro-organisms

• They are applied in agriculture, medicine, environmental conservation, and various industries for economic and research advantages

Applications of Micro-organisms in Agriculture

• Gene Technology: Enhances crop harvest by producing pest/drought-resistant crops with high nutrients
  • Genes of Erwinia uredovora are used to develop golden rice with vitamin A
  • Bacillus thuringiensis genes are mutated in Zea maize to produce toxins against crop pests
• Nitrogen Fixation: Rhizobium bacteria in legume nodules absorb atmospheric nitrogen, which is used commercially to increase legume yield
• Azotobacter, a free-living nitrogen-fixing bacteria, acts as bio-fertilizers in cultivation lands
• Producing Compost: Rapid decomposition of organic matter, adding minerals to the soil, and creating favorable conditions for plant growth
• Bio-pesticides: Used to control insect pests, e.g., Alternaria fungus combats aquatic weed, salvinia

Applications of Micro-organisms in Medicine

• Used to treat diseases caused by other micro-organisms and produce antibiotics, vaccines, and antitoxins
• Producing antibiotics: Chemicals from microbes that destroy or sabotage other micro-organisms
  • Fungi and bacteria produce antibiotics that kill bacteria and fungi but not viruses
• Antibiotics, such as Penicillin Amoxicillin, Tetracycline, and Erythromycin treat bacterial infections, while Griseofulvin treats fungi infections.
  • Penicillin was discovered by Alexander Fleming and is produced using the fungi Penicillium notatum
• Producing Vaccines: Vaccines contain an agent resembling a disease-causing micro-organism, often from weakened or killed microbes or their toxins
  • Vaccines can be made from weakened microbes (e.g., Polio, Tuberculosis, Measles), killed microbes (e.g., Cholera, Influenza, Typhoid), toxins of microbes (e.g., Tetanus, Diphtheria), or body parts of microbes using genetic engineering (e.g., Hepatitis B)
• Producing Anti-Toxins: Bio-chemical substances (toxins) produced by pathogenic bacteria are synthesized into vaccines by removing toxic components
  • Example: Tetanus

Applications of Micro-organisms in Industries

• Using micro-organisms in industrial activities for economic benefits is known as Industrial Microbiology.
• Used in large and small-scale industries
  • Producing dairy products (yoghurt, curd, cheese, butter)
  • Producing biogas
  • Metal extraction
  • Products based on plant fibres
  • Producing alcohol
  • Producing vinegar
  • Bakery industry
• Biogas production uses a mixture of organic materials (straw, cow dung, water) with anaerobic bacteria (Methanococcus) to produce methane gas
• Metal extraction from low-grade ores uses bio-leaching with microbes
  • Uranium and copper are extracted using bio-leaching
• Milk Based Products: When boiling milk, unfavourable bacteria are destroyed; Lactobacillus and Streptococcus are then used as culture in producing yoghurt. They turn Lactose into Lactic acid, which creates an acidic medium, retarding growth of other micro-organisms and enhancing preservation
• Product based on plant fibres: Plant fibres (coconut, hemp, palmyrah, agave) are separated by bacteria that digest Pectate compound
• Micro-organisms are commonly used for environmental conservation. The technology used to remove environmental pollutants using micro-organisms is known as bio-remediation.
  • Microbes are used to decompose the organic waste matter in polluted water
  • Pseudomonas; A kind of bacteria released on to the ocean water for the decomposition of oil layer on the ocean decompose hydrocarbons in oil
  • Heavy metals such as Chromium (Cr), Lead (Pb), Mercury (Hg) are released to the environment from different industries being sent through a tower which contains contain bacteria which removes them
  • Producing bio-degradable plastics

Favourable Impacts of Micro-organisms:

• Biological processes occur rapidly due to high growth and metabolic rates
• Various strains/varieties can act and multiply on various substances
• Microbes are easily used for genetic engineering because they possess simple genes
• Most micro-organisms are obtained at low cost from the environment
• Less energy is required compared to other industries
• Industries using microbes cause minimal environmental damage

Adverse Effects of Micro-organisms

• Microbes cause diseases in humans, plants, and animals

• They lead to food spoilage and economic damage

• Biological weapons are used adversely

• Bacteria, viruses, fungi, and protozoa are the groups of micro-organisms that cause diseases

• A micro-organism that can cause disease is termed a pathogen.

• Mosquitoes and flies act as vectors carrying the pathogen to a host.

• A host is an organism providing a substrate for pathogen growth.

  • Viruses (e.g., Dengue) use mosquitoes as vectors which then cause adverse symptoms to the host (man)

• Diseases caused by micro-organisms for humans are caused by air, water, food, contact and vectors etc.

  • Virus:
    • Cold: Method of Spreading is air Through the respiratory system
    • Dengue: Method of Spreading is mosquito vectors. The pathogen enters the body, Through the skin by mosquito bites
    • AIDS: Method of Spreading is blood and other fluids of an infected person. The pathogen enters the body, Through sexual contacts or blood transfusion
  • Bacteria:
    • Tuberculosis: Method of Spreading is air Through the respiratory system
    • Typhoid Fever: Method of Spreading is Polluted food and vectors such as housefly, The pathogen enters the body, Through digestive system with food
  • Protozoa:
    • Malaria: Method of Spreading is mosquito (vectors), The pathogen enters the body Through the skin by mosquito bite
    • Amoebic dysentery: Method of Spreading is Polluted water and food, The pathogen enters the body Through digestive system
    • Leishmaniasis: Method of Spreading is Vectors such as sand fly, The pathogen enters the body Through open wounds on the skin
  • Fungi:
    • Pityriasis: Method of Spreading is Contact of an infected person or through clothes, The pathogen enters the body, Through skin
    • Rashes: Method of Spreading is of an infected person The pathogen enters the body, Through skin

• Diseases caused by micro-organisms to plants

  • Powdery mildew disease is a fungal infection affecting parts of the plant, appearing White or gray powdery material
  • Late Blight is a fungal disease commonly affecting leaves, later turning the tree affected by it black
  • Wilting can be caused by Fungi or bacteria, and affects the xylem of the plant

• Food Spoilage caused by Micro-organisms multiplies as they covert food into unfavourable materials

• The toxins produced by micro-organisms are considered very harmful to human and can be known as biological weapons

  • Bacillus anthracis causative agent of Anthrax is an example of a biological weapon

Test your knowledge of microbiology, including the characteristics of algae, protozoa, viruses, and other microorganisms. Questions cover classification, environmental factors, and modes of movement. Assess your understanding of microbial life.