Understanding Microorganisms: From Pathogens to Biotechnology

Posted on Apr 30, 2024 in Biology

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1. Pathogenic Microorganisms

While some microorganisms are beneficial as normal flora, others are opportunistic organisms or pathogens that can cause harm. The risk of infection increases when an animal’s defenses are weakened. An epidemic is a disease affecting many individuals in a specific geographic area at a given time. Pandemics are widespread diseases affecting large areas.

Disease transmission can occur through various means:

  • Vectors: Organisms that transmit the disease.
  • Carriers: Individuals who harbor the disease without showing symptoms but can still transmit it.
  • Reservoirs: Places where microorganisms reside and from which diseases can be contracted.
  • Quarantine: Isolation of individuals to prevent the spread of infection.

A) Microbial Infection

Microbial infection occurs when pathogenic microorganisms enter and penetrate the body. Adherence is facilitated by fimbriae or molecules on the cell wall. Penetration often occurs through natural orifices like the mouth or nose. When an infection takes hold, the body produces antibodies to fight it. However, the bloodstream can carry the infection to other organs, causing a widespread or systemic infection.

B) Virulence

Virulence refers to a microorganism’s ability to infect. Factors contributing to virulence include:

  1. Toxins: Poisons produced by the organism. Exotoxins are proteins released by the organism, while endotoxins are lipopolysaccharides (LPS) that are part of the organism’s structure.
  2. Enzymes: Substances that hydrolyze membrane components, destroy tissue, and promote blood clotting, protecting the pathogen from macrophages.

2. Chemotherapy

Chemotherapy involves treating diseases using chemical substances. Chemotherapeutic substances can be:

  • Antibiotics: Naturally occurring substances produced by bacteria and fungi that inhibit the growth of other microorganisms. They work by preventing cell wall formation or DNA and RNA synthesis. Broad-spectrum antibiotics are effective against a wide range of microorganisms but do not treat viral infections.
  • Synthetic Chemotherapeutic Agents: Examples include sulfa drugs, AZT (used against AIDS), and chloroquine (used for malaria).

3. Microbial Biotechnology

Microbial biotechnology utilizes microorganisms for human benefit in various ways:

  • Fermentation Processes: Anaerobic catabolic processes that produce organic molecules like ethanol and lactic acid. Industrial fermentation occurs in fermenters with controlled conditions. Examples include ethanol production from glucose and lactic acid production from lactose.
  • Antibiotic Production: Bacteria and fungi, such as Penicillium, produce antibiotics. Improved cultivation and separation techniques enhance antibiotic production.
  • Vitamin and Amino Acid Production: Microorganisms produce vitamins like B12 and riboflavin, which are essential coenzymes in metabolic processes. Excess amino acids produced by microorganisms can be used as sweeteners and preservatives.
  • Insect Pest Control: Entomopathogenic microorganisms kill insects and larvae that damage crops, offering a safer alternative to insecticides.
  • Food Industry: Microorganisms play a crucial role in producing bread, dairy products, and other foods. Food safety regulations ensure that food products are free from harmful microorganisms.
  • Genetic Engineering: Involves transferring genes from a donor organism to a vector, creating recombinant DNA, and introducing it into a host organism. This technology is used to synthesize hormones (e.g., insulin), vaccines (e.g., measles), and immunological substances (e.g., interferon).
  • Wastewater Treatment: Microorganisms break down organic matter in wastewater, producing carbon dioxide, water, and methane. The biological oxygen demand (BOD) indicates the level of organic pollution in water.

4. Control of Microorganisms

Various methods are employed to control and protect against harmful microorganisms:

  • Physical methods: High temperatures (dry or moist heat), cold, and ionizing/non-ionizing radiation.
  • Chemical methods: Sterilizers like formaldehyde and disinfectants like iodine.