Biology Lecture 1: Microbial Cells

Biology of Microbial Cell

• Biology refers to the study of living organisms, while microbiology studies very small microorganisms or microbes that require a microscope.

Microorganisms (MOs)

• Include bacteria, algae, protozoa, fungi, and viruses
• Viruses are infectious agents or particles
• 3% of microbes are pathogens (disease-causing), while 97% are non-pathogenic
  • 87% of non-pathogens are beneficial and form indigenous microflora or microbiota
  • Microorganisms are ubiquitous (found everywhere)

History of Microbiology

• Antony Van Leeuwenhock discovered "animalcules" (microorganisms) in 1676
• Spontaneous Generation theory believed living organisms arise from decomposing matter
  • Contrasted with Biogenesis, which states life arises from pre-existing life

Contributions of Louis Pasteur

• Showed microbes cause fermentation and spoilage
• Disproved Spontaneous Generation
• Developed aseptic techniques (free from pathogenic microorganisms)

Germ Theory of Disease

• Diseases are transmitted by microbes from a diseased to a healthy person
• Examples: Diphtheria (Corynebacterium diphtheriae) and Tetanus (Clostridium tetani)

Contributions of Robert Koch

• Developed solid growth media
• Introduced pure culture techniques
• Developed simple stain technique
• Developed aseptic lab techniques
• Isolated bacteria as causative agents for Anthrax

Koch's Postulates

• Series of experimental steps to show a specific organism causes a specific disease

Spores and Sterilization

• Ferdinand Cohn discovered and described endospores
• Term "sterile" means complete removal of all life forms, including endospores

Branches of Microbiology

• Basic Microbiology: classifications, metabolism, nutrition, growth, and requirements
• Medical Microbiology: Human pathogens
• Industrial Microbiology: Microorganisms used to obtain industrial products
• Pharmaceutical Microbiology: Production of drugs, enzymes, solvents, and other products
• Agricultural Microbiology: Microorganisms as biofertilizers and biocontrol agents of plant pathogens
• Environmental Microbiology (Microbial Ecology): Microorganisms in pollution, biodegradation, and environmental processes