Famous Microbiologists and Their Contributions

Study Notes

Antonie van Leeuwenhoek, known as the "Father of Microbiology", made lenses and microscopes as a hobby and was one of the first to document bacteria, red blood cells, spermatozoa, muscle fibers, and crystals.
Robert Hooke, an English scientist, discovered microorganisms using a microscope and coined the term "cell".
Edward Jenner, known as the "Father of Immunology", developed the concept of vaccines and created the first vaccine against smallpox.

Louis Pasteur, a French scientist, developed the germ theory and conducted vaccination experiments against fowl cholera, anthrax, and rabies.
Pasteurization, a heating process to kill microorganisms, was named after him.
He also discovered microbial fermentation and developed liquid media for pathogenic bacteria growth.

Robert Koch, a German scientist, discovered the causative agents of tuberculosis, cholera, and anthrax.
He developed the bacterial culture method using agar on glass plates and invented Koch's postulates to identify disease-causing bacteria.

Bacteria are ubiquitous in nature, constituting normal flora on body surfaces and in the GI tract, and are involved in mutualism/symbiosis.
The bacterial cell envelope consists of a cell wall and phospholipid membrane.
Peptidoglycan/murein is unique to bacterial cell walls.
Gram-positive bacteria have a thicker peptidoglycan/murein layer, while Gram-negative bacteria have a thinner layer and an outer phospholipid membrane with porins.

Genus Mycoplasma lacks a cell wall.
Genus Corynebacterium, Mycobacterium, Nocardia, and Rhodococcus (CMNR group) have a complex cell wall with a mycolic acid layer (mycomembrane).
Phylum Chlamydiae lacks peptidoglycan and has an outer membrane with lipopolysaccharides (LPS).

Capsules are firmly attached to the cell wall and composed of polysaccharides or polypeptides.
Slime layers are loosely attached to the cell wall and composed of polysaccharides.
Biofilms are extracellular matrices of polysaccharides that allow bacteria to function together.

Cytoplasm consists of water, proteins, carbohydrates, lipids, and inorganic ions.
Nuclear material is organized into a single, long, tightly coiled, circular DNA molecule (nucleoid).
Plasmids are extrachromosomal DNA that can provide advantages like antimicrobial resistance and virulence factors.
Inclusions are storage granules that store polysaccharides, phosphorus, and sulfur.
Ribosomes are smaller and less dense than in eukaryotic cells, composed of 30S and 50S subunits.

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