Microbio prelims

• Microbiology is the study of small living things that are too small to be seen with the naked eye
• Branches of microbiology:

  • Bacteriology: study of bacteria
  • Virology: study of viruses
  • Mycology: study of fungi or mushrooms
  • Protozoology: study of protozoa
• Microbes and germs are microorganisms that cause disease or infection
• Pathogenicity is the capability of microorganisms to cause a disease
• Not all bacteria are pathogenic
• Antoni van Leeuwenhoek (1632-1723) discovered the microscope and observed "animalcules" or "little animals"
• Theodor Schwann proposed the Theory of Spontaneous Generation, stating that living things arise from non-living things
• Francesco Redi (1668) disproved the Theory of Spontaneous Generation through an experiment with meat and gauze
• Louis Pasteur (1861) is known as the Father of Modern Bacteriology and disproved the Theory of Spontaneous Generation through experiments with meat infusions
• Louis Pasteur's contributions include pasteurization, anthrax vaccine, and anti-rabies treatment
• John Tyndall observed the Tyndall Effect and made contributions to endospores, tyndallization, and fractional distillation
• Pasteurization is a process of food preservation where heat kills bacteria or pathogens
• Categories of microorganisms:

  • Cellular: consists of a cell
  • Categories include Prokaryotic (Bacteria, Archaeans) and Eukaryotic (Algae, Protozoa, Fungi)
  • Multicellular: consists of multiple cells
  • Acellular: absence of cell, includes Virus, Viroids, and Prions
• Prokaryotes have no nucleus, nuclear membrane, or organelles, while Eukaryotes have a true nucleus and organelles
• Bacteriology is the study of bacteria, especially in relation to medicine
• 3 phenotypic categories of bacteria: Gram-positive, Gram-negative, and Atypical
• Gram-positive bacteria stain blue or purple and have a thicker cell wall, while Gram-negative bacteria stain pink or red and have a thinner cell wall
• Domain Archaea is an ancient form of bacteria, most of which are extremophiles living in extreme environments
• Morphology of bacteria includes different shapes like cocci, bacilli, spiral, vibrio, spirilla, spirochetes, and pleomorphic
• Arrangement of bacteria can be singles, pairs, chains, clusters, tetrads, sarcina, or palisade
• Bacteria are measured in micrometers, with 1 micrometer equal to 1/25,000 inches or 0.001 mm
• Bacteria reproduce via transverse binary fission with phases like lag phase, log phase, stationary phase, and death phase
• Growth requirements for bacteria include oxygen (aerobe, anaerobe), temperature (psychrodurics, psychrophiles, mesophiles, thermophiles, thermodurics), pH, moisture, osmotic pressure, and nutrition
• Metabolic enzymes in bacteria speed up chemical reactions and are affected by factors like substrate concentration, enzyme concentration, pH, and temperature
• Endoenzymes are produced and react within the cell, while exoenzymes are produced within the cell but released outside to catalyze extracellular reactions
• Metabolism in bacteria involves chemical reactions that produce metabolites, with catabolism breaking down large molecules into smaller ones
• Catabolism produces energy for the cell
• Metabolism involves anabolism, the building of complex molecules from simpler ones
• Metabolism:

  • Chemical reactions occurring in a cell
  • End product of metabolism is metabolite
• Catabolism:

  • Breaking down of large molecules into smaller ones
  • Produces energy needed by microorganisms
  • Involves breaking down of bonds
• Anabolism:

  • Building of small molecules into larger ones
  • Requires energy to create bonds
• Carbon sources:

  • Photoautotrophs
  • Photoheterotrophs
  • Chemoautotrophs
  • Chemoheterotrophs
• Photoautotrophs:

  • Uses photosynthetic energy to reduce carbon dioxide at the expense of water
  • Does not require organic matters for growth
  • Example: Cyanobacteria
• Photoheterotrophs:

  • Uses photosynthetic energy to use CO2 at the expense of water
  • Requires organic compounds for growth
  • Example: Purple Sulfur and Green Sulfur bacteria
• Chemoautotrophs:

  • Uses inorganic substrates as a reductant + carbon dioxide as carbon source
  • Does not require organic matters for growth
  • Example: Archaea + few bacterial genera
• Chemoheterotrophs:

  • Requires organic carbon for growth
  • Glucose supports the fermentative and respiratory growth
  • Example: Most bacteria + few archaea
• Bacterial cell and its structures:

  • Cell wall maintains cell shape
  • Cell wall can be Gram + or Gram -
  • Peptidoglycan is susceptible to tears, saliva, and mucus due to lysozyme
  • Peptidoglycan maintains cell wall and is a target of some antibiotics like Penicillin
• Protoplast:

  • Seen in bacteria without peptidoglycan layer
  • Resistant to penicillin
• Teichoic acid:

  • Protein attached to peptidoglycan layer
  • Only found in Gram + bacteria
  • Antigenic and triggers immune response
• Outer membrane:

  • Only found in Gram -
  • Composed of lipopolysaccharide, lipoprotein, and phospholipids