History of Microbiology

• Ancient belief that bad air causes diseases is the Miasma Hypothesis.
• Aqueducts were built by Romans to remove 'bad air' as a means to prevent diseases.
• Hippocrates is the Father of Western medicine who believed diseases originated from the environment.
• The Greek historian Thucydides observed that survivors of the Plague became immune.
• Antonie van Leeuwenhoek was the first to observe microorganisms using a microscope.
• Robert Koch proved that specific microbes cause specific infections.
• Ignaz Semmelweis demonstrated that hand disinfection reduces infections in expecting mothers.
• Joseph Lister introduced the practice of preventing infection by using sterile techniques during surgery.
• Introducing a vaccine to stimulate immunity against a disease is done through the process developed by Edward Jenner.
• Microorganisms, including bacteria, fungi, protozoa, and viruses, are microscopic organisms.
• The taxonomic system is the science of classifying and organizing living organisms into categories
• It was developed by Carl Linnaeus
• The eight levels of classification in biology are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• A helpful mnemonic is: KING PHILIP CAME OVER FOR GOOD SOUP

Writing a Scientific Name:

• Include initials
• Include a table number
• Capitalize the genus name (e.g., Escherichia)
• Write the species name in lowercase (e.g., coli)

DNA Sequencing Steps:

• Extract DNA by collecting and isolating DNA from a sample
• Amplify the DNA using PCR (Polymerase Chain Reaction) to make many copies
• Label the DNA by by adding markers or special tags to help identify the sequence
• Read the sequence: Use a machine to determine the order of the nucleotides (A, T, G, C) in the DNA

Autotrophic Identification:

• Conduct a growth test by growing the specimen in media without organic food (like glucose); growth indicates it is an autotroph
• Conduct a light test: Growth in light but not in darkness indicates it is a photosynthetic autotroph
• Conduct a chemical test: Growth using chemicals such as hydrogen sulfide indicates it’s a chemosynthetic autotroph

Identifying specimens that are Heterotrophic:

• Growth Test: Grow them in media containing organic carbon (like glucose). If they grow, they are heterotrophs.
• No Light Needed: Heterotrophs do not require light for growth. They rely on organic material, not photosynthesis.
• Carbon Source Test: If they only grow with organic compounds (like sugars or proteins), they are heterotrophs.

Identifying if a specimen has a Nucleus:

• If a nucleus is present, it is likely a eukaryote; absence indicates it is a prokaryote
• Eukaryotes have organelles such as mitochondria and chloroplasts; prokaryotes do not have membrane-bound organelles

Biochemical Testing:

• Sugar Test: Assess if the microbe can break down sugars, like glucose
• Catalase Test: Add hydrogen peroxide to the microbe; bubbles indicate the enzyme catalase is present
• Urease Test: If the microbe breaks down urea, the color of the test medium changes

Staining Techniques:

• Gram Stain: Stains bacteria either purple (Gram-positive) or pink (Gram-negative)
• Endospore Stain: Stains tough spores to aid in identifying certain bacteria